Dissertations / Theses on the topic 'Residual decomposition'
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1
Sousa, Adervan Fernandes. "Mineralization of nutrients and plant growth in soils irrigated with wastewater from oil extraction." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16918.
Abstract:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO grande volume de Ãgua utilizado na agricultura compromete a sua disponibilidade para o consumo humano. Diante desse problema, Ã necessÃrio avaliar a utilizaÃÃo de Ãguas residuais na produÃÃo agrÃcola, como uma opÃÃo para a conservaÃÃo dos recursos hÃdricos. Ãguas residuais oriundas de campos de petrÃleo podem ser uma boa opÃÃo para irrigaÃÃo, especialmente em regiÃes de pouca e alta variabilidade de chuvas como o Nordeste brasileiro. No entanto, Ã necessÃrio avaliar os seus efeitos no solo, como acÃmulo de nutrientes e decomposiÃÃo da matÃria orgÃnica, bem como no aspecto nutricional e no crescimento das plantas. Os objetivos deste trabalho foram: i) Avaliar as mudanÃas ocorridas nos sais solÃveis e nas fraÃÃes da matÃria orgÃnica do solo e no crescimento de plantas de girassol (Helianthus annuus L.) cv. BRS 321, cultivadas em solo de textura arenosa irrigado com Ãgua residual oriunda da extraÃÃo de petrÃleo tratada por filtragem e osmose reversa; ii) Avaliar as alteraÃÃes nutricionais do girassol (Helianthus annuus) BRS 321 irrigado com Ãgua residual da extraÃÃo de petrÃleo e os efeitos sobre a produÃÃo de biomassa e de aquÃnios; e iii) Avaliar a decomposiÃÃo dos restos culturais de girassol (Helianthus annuus) cv. BRS 321 em Ãreas irrigadas com Ãgua residual da extraÃÃo de petrÃleo. O girassol foi cultivado durante trÃs perÃodos sucessivos em Ãreas irrigadas com Ãgua residual da extraÃÃo de petrÃleo tratada por filtragem (APF) e por osmose reversa (APO) ou Ãgua subterrÃnea do aquÃfero AÃu (ACA). Ao fim de cada ciclo foram determinados os valores de pH, condutividade elÃtrica (CE), a razÃo de adsorÃÃo de sÃdio (RAS) e os teores de Na, Cl, Mg, Ca, K, HCO3-, Ag, As, B, Ba, Cd, Co, Cr3+, Hg, Ni, Pb, Zn, alÃm de C nas fraÃÃes hÃmicas. Em raÃzes, parte aÃrea e aquÃnios determinaram-se os teores de N, P, K, Ca, Mg, S e Na e avaliaram-se o crescimento e o acÃmulo de biomassa. AlÃm disso, avaliou-se a decomposiÃÃo dos resÃduos da parte aÃrea das plantas de girassol. Houve alteraÃÃes nos atributos quÃmicos do solo, em destaque o acrÃscimo de sais, que foi maior nas Ãreas irrigadas com APF, e elevaÃÃo do pH, independente do tipo de Ãgua utilizado. A elevaÃÃo da salinidade e alcalinidade do solo reduziu o crescimento e o acÃmulo de biomassa das plantas. AlÃm disso, a irrigaÃÃo proporcionou alteraÃÃes nutricionais das plantas, que refletiram no crescimento e na produÃÃo de aquÃnios do girassol e na decomposiÃÃo dos resÃduos da cultura, com efeitos positivos ou negativos, conforme o tratamento da Ãgua residual. Concluiu-se que a Ãgua residual da extraÃÃo de petrÃleo utilizada na irrigaÃÃo afeta os atributos quÃmicos do solo, bem como a composiÃÃo nutricional e o desenvolvimento das plantas, principalmente quando irrigadas com a APF. AlÃm disso, a irrigaÃÃo com Ãgua residual alterou a mineralizaÃÃo dos resÃduos vegetais do girassol, mas nÃo a de decomposiÃÃo do carbono orgÃnico nas fraÃÃes hÃmicas.
The large volume of water used in agriculture compromises its availability for human consumption. Faced with this problem, it is necessary to evaluate the use of wastewater in agricultural production as an option for the conservation of water resources. Wastewater from oil fields can be a good choice for irrigation, especially in regions of low or high rainfall variability, as in the Brazilian Northeast. However, it is necessary to evaluate its effects on the soil, such as the accumulation of nutrients and decomposition of organic matter, as well as the nutritional aspect and plant growth. The aims of this study were: i) to assess the changes that take place in the soluble salts and soil organic matter fractions, and in the growth of plants of the BRS 321 cultivar of the sunflower (Helianthus annuus L.) cultivated in soil of a sandy texture and irrigated with wastewater obtained from oil extraction and treated by filtration and reverse osmosis; ii) to assess the nutritional changes in the BRS 321cultivar of the sunflower (Helianthus annuus) irrigated with wastewater from oil extraction, and the effects on biomass and achene production; and iii) to evaluate the decomposition of plant residue from the BRS 321 cultivar of the sunflower (Helianthus annuus) in areas irrigated with wastewater from oil extraction. The sunflower was grown for three successive periods in areas irrigated with wastewater from oil extraction treated by filtering (APF) and reverse osmosis (APO), or with groundwater from the AÃu aquifer (ACA). At the end of each cycle, pH values were determined, together with electrical conductivity (EC), the sodium adsorption ratio (SAR) and the levels of Na, Cl, Mg, Ca, K, HCO3-, Ag, As, B, Ba, Cd, Co, Cr3+, Hg, Ni, Pb, Zn, and of C in the humic fractions. The concentrations of N, P, K, Ca, Mg, S and Na were determined in the roots, shoots and achenes, along with growth and the accumulation of biomass. In addition, the decomposition of shoot residue from the sunflower plants was evaluated. Changes were seen in the chemical properties of the soil, highlighting an increase in salts, which was greater in the areas irrigated with APF; a rise was also seen in pH irrespective of the type of water used. The rise in soil salinity and alkalinity reduced the growth and accumulation of plant biomass. Moreover, irrigation resulted in nutritional changes in the plants, which were reflected in the growth and production of achenes, and in the decomposition of the plant residue, having positive or negative effects according to the treatment of the wastewater. It was concluded that wastewater from oil extraction used in irrigation affects the chemical properties of the soil as well as the nutritional composition and development of the plants, especially when irrigated with APF. Furthermore, irrigation with wastewater changed the mineralisation of the sunflower plant residue, but not the decomposition of the organic carbon in the humic fractions.
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Santos, Carlos Antonio Barreto dos. "Cons?rcios de esp?cies de cobertura de solo para aduba??o verde antecedendo ao cultivo de milho e repolho sob manejo org?nico." Universidade Federal Rural do Rio de Janeiro, 2009. https://tede.ufrrj.br/jspui/handle/tede/535.
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Four plant species, intercropped or not, were evaluates in the State of Rio de Janeiro for Green manuring and soil covering prior to corn or cabbage crops. Such crops were submitted to a no-tillage and organic farming system. The study relating to corn was carried out in Baixada Fluminense (Serop?dica) at 33 m above sea level, whereas the cabbage experiment was the located in the South-Central Region (Paty do Alferes) at 680m. In bony experiments a randomized block design was employed with 12 treatments and four replicates. The species lazed for soil covering were: Crotalaria juncea (C), sorghum Sorghum bicolor (S), sunflower Heliantus annus (G) and castor bean Ricinus communis (M). Treatments involving such soil covering species corresponded to their monocrops ad the following intercrops: C+G, C+S, C+M, C+G+S, C+S+M and C+G+S+M. The control treatment consisted of fallow plots whove spontaneous vegetations was cut down on the day subsequent corn and cabbage were planted. In Baixada Fluminense, the previous intercrops favored epigeous edafic fauna diversity compared to fallow, either during vegetative cycle or after cutting except for castor bean monocrop, all treatments led to reduced need reinfestation in comparison to fallow plots. Corn yield (immature ears) was higher after monocrops of the soil covering species and also after fallow. Crotalaria showed in outstanding potential as green manure considering that organic suplementar corn fertilizing were proceeded only in plots previously cultivated to such legume species. The greatest cumulative e amount of above-ground biomass resulted from crotalaria monocrop probably contributing to a superior corn yield. In the South-Central field experiment the highest values for biomass productin were again obtained from crotalaria monocrop, its intercrops with each of the other soil covering species (C+G, C+S and C+M), and the triple intercrop with sorghum plus castor bean (C+S+M). Decomposition rates for the cut down plant residues in situ differed between intercrops and monocrops. Cabbage yield was as cell favoured by previous crotalaria and its intercrops, with exception of the intercrop in which all four plant species participated. Results have demonstrated the adequacy of crotalaria for rotational system with commercial crops under organic management. The experiments otherwise indicated that combining the legume with other soil covering species may lead to additional advantages in terms of crop residues persistence on soil surface and ed?fica fauna stimulation.
Avaliaram-se, no Estado do Rio de Janeiro, quatro esp?cies bot?nicas, consorciadas ou n?o, para aduba??o verde e cobertura do solo, antecedendo as culturas de milho verde e repolho. Estas culturas foram implantadas em sistema plantio direto e submetidas ao manejo org?nico. O estudo com o milho verde foi conduzido na Baixada Fluminense (Serop?dica) a 33 m de altitude enquanto o estudo com o repolho teve lugar na regi?o Centro Sul (Paty do Alferes) a 680m. Em ambos os experimentos, empregouse o delineamento de blocos casualizados, envolvendo 12 tratamentos com quatro repeti??es. As esp?cies de cobertura do solo utilizadas foram: Crotalaria juncea (C), girassol Heliantus annus (G), sorgo Sorghum bicolor (S) e mamoneira Ricinus communis (M). Os tratamentos relativos ?s esp?cies de cobertura corresponderam aos respectivos monocultivos e aos cons?rcios: C+G, C+S, C+M, C+G+S, C+G+M, C+S+M e C+G+S+M. O tratamento controle foi representado pelas parcelas que permaneceram em pousio, cuja vegeta??o espont?nea foi ro?ada por ocasi?o dos plantios subsequentes de milho ou repolho. Nas condi??es da baixada fluminense, os cons?rcios favoreceram a diversidade da fauna ed?fica ep?gea, quando comparados com o pousio, tanto ao longo do ciclo vegetativo das esp?cies de cobertura quanto ap?s o corte. Com exce??o do monocultivo de mamoneira, os demais tratamentos provocaram redu??o dos n?veis de reinfesta??o de ervas espont?neas, relativamente ao pousio. A produtividade do milho em espigas verdes foi superior quando em sucess?o aos monocultivos das esp?cies de cobertura e pousio. A crotal?ria revelou destacado potencial como adubo verde, tendo em vista que somente nas parcelas onde foi previamente cultivada o milho n?o recebeu fertiliza??o org?nica suplementar. A maior quantidade acumulada de biomassa a?rea seca tamb?m resultou do monocultivo de leguminosa, o que provavelmente contribuiu para o rendimento superior do milho. No ensaio conduzido na regi?o Centro Sul, os valores mais elevados de biomassa produzida foram tamb?m obtidos a partir da crotal?ria em monocultivo, de seu cultivo consorciado com cada uma das outras plantas de cobertura (C+G, C+S e C+M) ou do triplo cons?rcio com sorgo e mamoneira (C+S+M). As taxas de decomposi??o in situ dos res?duos vegetais ro?ados distinguiram os cons?rcios dos monocultivos. Em termos de produtividade, o repolho foi beneficiado pelo pr?-cultivo de crotal?ria e seus cons?rcios, com exce??o daquele do qual participaram todas as quatro plantas de cobertura. Os resultados demonstraram adequa??o da Crotalaria juncea para sistemas rotacionados com culturas, de interesse comercial sob manejo org?nico. Indicaram, todavia, que combina??es desta leguminosa com outras esp?cies nos pr?-cultivos podem acarretar vantagens adicionais, ligadas ? persist?ncia da palhada distribu?da na superf?cie do solo, a partir do corte da biomassa a?rea, e ? diversidade da fauna ed?fica ep?gea.
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Marella, Venkata S. S. R. "Understanding plant residue decomposition in shrubland ecosystem." Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/understanding-plant-residue-decomposition-in-shrubland-ecosystem(6dcfe4c8-c9a4-46fe-aeb7-58b0a6e0fbf0).html.
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Litter decomposition is a key component in ecosystem C and nutrient cycling. Shrubland litter decomposition is not well understood, even though shrublands cover a significant proportion of earth surface. This project aims to investigate the decomposition of shrubland plant residue (Cistus monspeliensis L.). The first and second experimental chapters of this thesis present the data about root chemistry, C and N mineralisation from the decomposing roots. Root tissue chemistry varies significantly with age, younger roots consist of higher relative amounts of N, P, K, soluble compounds, conversely Ca, hemicellulose, cellulose concentrations are higher in older roots. Faster short-term C, and N mineralisation rates were observed in senescing younger roots compared to the older roots under our experimental conditions. The third experimental chapter is about leaf litter decomposition study using litter bag technique. Accumulated mass loss from the decomposing leaf litter is a biphasic process where initial rapid mass loss followed by relatively slower phase. Among the various leaf litter decomposition parameters lignin: N best explained the accumulated mass loss. Fourth experimental chapter is an attempt to understand the 14C mineralisation process from decomposing soluble and insoluble components of above and below ground plant parts. Soluble components have shown faster 14C mineralisation compared to the insoluble fractions of above (stem and leaf) and belowground (roots) plant components. Belowground plant components have shown a distinctive 14C mineralisation pattern with more % 14C entering in to microbial biomass pool compared to the aboveground components which will have consequences on whole ecosystem C cycle. Results from final experimental chapter indicate that C sourced by hyphal biomass reside longer duration even after death thereby contribute significant amounts of C to the belowground. However, further long-term studies that includes multi plant species under filed conditions are needed before these results extrapolate to the shrubland ecosystem.
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Whetton, Matthew. "Polyphenol/protein interactions during the decomposition of tropical lugume residues." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248053.
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Ehaliotis, Constantinos. "Nitrogen turnover during decomposition of recalcitrant plant residues in acid soils." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243408.
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Chandra, Varunesh. "Nitrous oxide and ammonia emissions from crop residue decomposition in soils." Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS204.pdf.
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La décomposition de résidus agricole dans les sols entraine une augmentation des émissions d’oxyde nitreux et d'ammoniac. C'est la position de l’incorporation des résidus qui affecte ces émissions gazeuses. Nous avons réalisé des expériences en laboratoire avec trois sols différents - des sols sableux à petites particules, des sols argileux calcaires et des sols argileux légèrement calcaires – auxquels nous avons incorporé des résidus de trèfle rouge et de blé. Les résidus ont été incorporés dans trois positions dans des microcosmes de sol - à la surface, mélangés à la couche supérieure et intercalés entre deux couches de sol, afin de simuler des scénarios réels. Nous avons constaté que les résidus placés en surface sur le sol présentaient les flux d'ammoniac les plus élevés. Les résidus placés en couches et mélangés présentaient des flux d'oxyde nitreux plus élevés. Les flux des résidus de trèfle rouge étaient plus élevés que ceux du blé en raison de la forte teneur en azote des premiers. Nous avons utilisé ces données de flux obtenues pour tester un modèle d’émission d'oxyde nitreux et d'ammoniac construit en couplant les modèles CANTIS, NOE et de volatilisation de l’ammoniac. Nous avons constaté que les simulations du modèle étaient sous-estimées bien qu'elles correspondent bien qualitativement aux observations expérimentalesCrop residues are organic inputs to soil that enhance soil carbon stocks. Although, their decomposition in soils have been showed to cause higher nitrous oxide and ammonia emissions. On analysing related literature, we found that the position of residue incorporation affects these gaseous emissions. We carried out laboratory experiments with three different soil - small particled sandy, calcareous clayey and slightly calcareous clayey soils, with red clover and wheat residues incorporated in them. The residues were incorporated in three positions in soil microcosms - on the surface, mixed in the top layer and layered between two soil layers, to simulate real world scenarios. We found that surface placed residues on soil had the highest ammonia fluxes. While layered and mixed residues had higher nitrous oxide fluxes. The fluxes from red clover residue were higher than wheat owing to high nitrogen in the former. We used this flux data obtained to test a constructed nitrous oxide and and ammonia emission model by coupling CANTIS, NOE and ammonia volatilisation models. We found that the model simulations were underestimated although they were corresponding well qualitatively with the experimental observations
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Burgess, Magdalena S. E. "Crop residue decomposition and nitrogen dynamics in corn under three tillage systems." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36879.
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Decomposition and N dynamics of grain-corn residues were investigated in a field study in southwestern Quebec, with particular reference to the roles of different plant parts (stems, leaves etc.) in determining overall residue mass loss and N content. A litterbag study was conducted, with surface and buried placements in plots under three tillage systems (no-till, reduced tillage, and conventional tillage, established five years before litterbag placement). Residue mass loss and N content were monitored over a two-year period. Separate data were obtained for leaves, stems, husks, and cobs. Net values for all residues combined were calculated taking into account initial proportions of each plant part at harvest. Overall estimates were made based on residue depth-distribution typical of each tillage system. A spreadsheet-based model of surface residue mass loss was developed, incorporating litterbag mass and other surface-residue data, in order to determine how well litterbag results predicted surface residue mass loss in the field, and to test alternative assumptions regarding residue decomposition and/or burial. Buried residues lost mass more quickly than surface residues, as expected. Thus residue breakdown would be fastest in a conventional system, slowest under no-till, and intermediate with reduced tillage. Substantial decreases in mass and residue N content occurred between fall placement and first sampling in spring, despite low temperatures for much of this period. Mass loss in the first period was substantial for stems as we as husks and leaves. Cobs decomposed most slowly throughout. Nitrogen dynamics, including effects of depth on residue N content, differed greatly by residue type. All the lower-N residues (cobs, husks, stems) immobilized N at some point. However, during the two-year study, N immobilization by one or more residue types was always counterbalanced or exceeded by N release by other residue, at least for the sampling intervals included. Pa
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Si, Weiduo. "The effect of plant residue decomposition on microbial community composition in soil." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324866.
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McKee, Alex Clive Seymoore. "Analytical solutions of orientation aggregation models, multiple solutions and path following with the Adomian decomposition method." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/7349.
Abstract:
In this work we apply the Adomian decomposition method to an orientation aggregation problem modelling the time distribution of filaments. We find analytical solutions under certain specific criteria and programmatically implement the Adomian method to two variants of the orientation aggregation model. We extend the utility of the Adomian decomposition method beyond its original capability to enable it to converge to more than one solution of a nonlinear problem and further to be used as a corrector in path following bifurcation problems.
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He, Yuxin. "Crop residue management and its impacts on soil properties." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19043.
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Doctor of PhilosophyAgronomy
DeAnn R. Presley
Crop residue removal for livestock feeding and biofuel production at large scales must be evaluated to assess impacts on soil productivity and properties. Among all the potential negative impacts, wind erosion is a major concern in the central Great Plains. We conducted an on-farm study from 2011 to 2013 by removing crop residue at five levels (0, 25, 50, 75, and 100%) to determine the effects of crop residue removal on soil wind erosion parameters such as dry aggregate size distribution including soil wind erodible fraction (EF <0.84 mm aggregates), geometric mean diameter (GMD) and geometric standard deviation (GSD), dry aggregate stability, and soil surface roughness. The sub-model of Wind Erosion Prediction System (WEPS) developed by the USDA-ARS, Single-event Wind Erosion Evaluation Program (SWEEP) is a stand-alone companion software package that can be applied to simulate soil loss and dust emission from a single windstorm event. We applied measured data (i.e. EF, GMD, GSD, and roughness) to SWEEP for predicting wind velocity that can initiate wind erosion and soil loss under each crop residue removal condition with wind velocity at 13 m sˉ¹. The threshold wind velocity to initiate wind erosion generally decreased with increase in crop residue removal levels, particularly for residue removal >75%. The total amount of soil loss in 3 hours ranged from about 0.2 to 2.5 kg mˉ² and depends on soil condition and crop residue cover. On the other hand, high-yielding crops can produce abundant crop residue, which then raises the question that if a farmer wants to reduce residue, what could they do without removing it? The application of fertilizer on crop residue to stimulate microbial activity and subsequent decomposition of the residue is often debated. We conducted wheat straw decomposition field experiments under different fertilizer rates and combinations at three locations in western Kansas following wheat harvest in 2011 and 2012. A double shear box apparatus instrumented with a load cell measured the shear stress required to cut wheat straw and photomicrography was used to measure the cross-sectional area of wheat straw after shearing. Total C and N were also analyzed. The fertilizer rate and timing of application during summer 2012 and Fall 2013 at the Hays site had impacts on wheat straw shear stress at break point. Across site years, earlier (fall) fertilizer application generally resulted in lower remaining aboveground biomass as compared to a spring application. Multivariate and linear regressions suggested that N and C:N ratio partially explain the results observed with respect to treatment effects on winter wheat residue decomposition.
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Haron, Khalid. "Nutrient cycling in an oil palm (Elaeis guineensis Jacq.) plantation : residues decomposition and implications for management." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361325.
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Raucci, Guilherme Silva. "Greenhouse gas assessment of Brazilian soybean production and postharvest nitrous oxide emissions from crop residues decomposition." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-30032015-151057/.
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Brazil is one of the world\'s largest producers and exporters of soybeans. The oil and meal obtained from grains are important components of biodiesel and animal feed chains. In recent years, international standards and certifications were developed to promote sustainability in the agricultural supply chain. In this context, greenhouse gases (GHG) emissions in the products life cycle has been the main point of interest to the scientific community and consumers. Few studies have evaluated the GHG emissions in soybean cultivation with specific data for the Brazilian reality. The aim of this study was to evaluate the main sources of GHG in soybean production in the State of Mato Grosso, Brazil. We evaluated 55 farms in the crop years of 2007/08, 2008/09 and 2009/10, accounting for 180,000 hectares of soybean cultivation area and totaling 114 individual situations. The results indicated that the largest source of GHG in the soybean production is the decomposition of crop residues (36%), followed by fuel use (19%), fertilizer application (16%), liming (13%), pesticides (7%), seeds (8%) and electricity consumed at the farms (<1%). The average GHG emissions considering the three crop years were 0.186 kg of CO2eq kg-1 of soybean produced. Based on these results, field experiments were conducted to quantify N2O emissions from the decomposition of soybean crop residues in different climatic regions and harvest periods in Brazil. Our results show that, in field conditions, the contribution of N2O emissions from senesced and desiccated residues that remain on field after soybean harvest are unlikely to represent a significant source of N2O loss above normal background soil emissions. These results were also supported by the laboratory incubation experiment, indicating that the IPCC methodology for estimating N2O emissions from soybean crop residues may provide overestimations for the Brazilian conditions. The results of this study provide relevant and specific information to producers, industry and scientific community regarding the environmental impacts associated with soybean production in BrazilO Brasil é um dos maiores produtores e exportadores mundiais de soja. O óleo e farelo obtidos dos grãos são componentes importantes das cadeias do biodiesel e ração animal. Nos últimos anos, normas e certificações internacionais foram desenvolvidas para promover a sustentabilidade na cadeia de produção agrícola. Nesse contexto, as emissões de gases de efeito estufa (GEE) no ciclo de vida dos produtos tem sido o principal ponto de interesse para a comunidade científica e consumidores. Poucos estudos avaliaram as emissões de GEE no cultivo da soja com dados específicos para a realidade brasileira. O objetivo deste estudo foi determinar as principais fontes de GEE na produção de soja em Mato Grosso, principal estado produtor brasileiro. Foram coletados dados de 55 fazendas nos anos-safra de 2007/08, 2008/09 e 2009/10, totalizando 114 avaliações. Os resultados indicaram que a maior fonte de GEE na produção de soja é a decomposição de resíduos culturais (36%), seguido pelo uso de combustível (19%), aplicação de fertilizantes (16%), calagem (13%), pesticidas (7%), sementes (8%) e eletricidade consumida nas fazendas (<1%). A emissão média considerando os três anos-safra avaliados foi 0,186 kg de CO2eq kg-1 de soja produzido. Com base nesses resultados, foram desenvolvidos experimentos em campo para quantificação das emissões de N2O proveniente da decomposição dos resíduos culturais da soja em diferentes regiões climáticas e períodos de colheita no Brasil. Adicionalmente, foram realizadas incubações em laboratório com materiais de soja em diferentes estágios de desenvolvimento. Os resultados indicaram que resíduos culturais de soja que permanecem no campo após a colheita não representam uma fonte significativa de N2O. Os resultados obtidos neste estudo fornecem informações relevantes para produtores, indústria e comunidade científica quanto aos impactos ambientais associados à cultura da soja no Brasil
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Mascia, Nicola. "Study of the thermo-oxidative decomposition of beer production residues for their use in valorisation processes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22691/.
Abstract:
The accumulation of huge amounts of food wastes every year has led to environmental degradation and especially to significant loss of valuable material.
Steady consumption of beer results in a steady output of residues. Brewer’s spent grain (BSG) is the most abundant by-product generated in the beer-brewing process. BSG consists of the barley grain husks together with parts of the pericarp and seed coat layer that is obtained as solid residue after the production of beer wort. Despite the wide range of possible applications, its main use is limited to animal feed or simply deposition to landfills. The study of alternative uses of BSG is appropriate, both from the perspective of the brewer who can benefit from the valorisation but also from an environmental outlook. However, a significant understanding gap regarding the variability of this low-cost residue, its influence in the valorisation process and its use in biorefineries exists.
This study attempts to characterize two different types of BSGs and the malts by which they are composed in terms of elemental composition, higher heating value, content of volatiles, fixed carbon, humidity, ash yield and to study the kinetic mechanism of decomposition during thermo-oxidative combustion. In terms of methodology, proximate analysis, ultimate analysis and calorific values were performed, as like as thermogravimetric analysis.
Thermogravimetric thermograms were determined at different heating rates, using oxygen as oxidative atmosphere. The thermo-chemical reactions were mathematically described through the definition of the main kinetic parameters: activation energy, pre-exponential factor, model of reaction. The so-called kinetic triplet was calculated through the application of iso-conversional methods, Master-Curves and Perez-Maqueda criterion.
The results of this study will serve as the baseline for the description of the energy recovery process in a reactor that uses brewer’s spent grain residues as feedstock.
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Pimentel, Laisa Gouveia. "Decomposition dynamics of sugarcane straw in the central-southern Brazil." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-21032018-124822/.
Abstract:
The adoption of mechanical unburned sugarcane harvesting increases the quantity of straw left on the soil. This material has a high potential for 2G ethanol and bioelectricity production. Although the straw maintenance has an essential role in the soil properties and crop performance. The straw decomposition is a key process to investigate and to inform the correct removal management decisions. Diverse factors affect the decomposition rate, such as: quality and quantity of straw; edaphoclimatic conditions; and management practices. Therefore, we conducted a field study at two sites within central-southern Brazil, the largest sugarcane-producing region in the world, encompassing two harvesting seasons (rainy and dry) over two years to evaluate the sugarcane straw decomposition dynamics under different removal rates. The main hypothesis is that the high removal unbalances the soil environment and reduce de C supply for the microorganisms, decreasing the microbial activity and consequently the straw decomposition rate. The straw removal management affected the decomposition rate, which the lowest decomposition was associated with high removal. The C and N loss was two- and threefold greater in the second year than in the first year of experimentation, respectively. Overall, the straw cellulose decreased by 13%, the hemicellulose 7%, and the lignin proportionally enriched by 92% after two years. Throughout the decomposition process, the straw chemical changes were detected using the traditional method, wet chemical extractions, and using the spectroscopy technique, Diffuse Reflectance Infrared Fourier Transform DRIFT. In this sense, in order to trace straw cellulose and hemicellulose changes we suggested the use of 896, 987, 1173, and 1447 cm-1 peaks, whereas to trace lignin changes, the absorbance at 1510 cm-1 seems to be an efficient predictor. The soil bacterial community was most affected by the time of decomposition. The straw quality explained 23.2% of the total bacterial variation, in which hemicellulose accounting for 17.2% of this variation. Moreover, the bacterial structure was subtle affected by the sugarcane straw removal. Overall, our study showed that the straw removal for 2G ethanol and bioelectricity production affect the straw decomposition dynamics in commercial sugarcane areas in Brazil. The time was the main regulator of changes in straw chemical contents and in the soil bacterial structure. The use of crop residues for energy purposes is one of the principal alternatives to increase bioenergy production in the next few years. However, the sugarcane straw removal should be done with prudence, since the straw removal rate affected the straw decomposition dynamics and consequently it should affect the nutrient recycling and C cycle.A adoção da colheita mecanizada sem queima prévia da cana-de-açúcar aumenta a quantidade de palha sobre o solo. Essa palha tem um alto potencial para produção de etanol 2G e bioeletricidade. No entanto, a manutenção da palha tem papel essencial nas propriedades do solo e no desempenho das culturas. A decomposição da palha é um processo chave para investigar e informar sobre corretas decisões acerca do manejo da remoção. Diversos fatores afetam a taxa de decomposição, tais como: qualidade e quantidade da palha; condições edafoclimáticas; e práticas de manejo. Portanto, realizamos um estudo de campo em dois locais no centro-sul do Brasil, maior região produtora de cana-de-açúcar no mundo, abrangendo duas épocas de colheita (chuvosa e seca) ao longo de dois anos para avaliar a dinâmica de decomposição da palha da cana-de-açúcar sob diferentes taxas de remoção. A principal hipótese é de que a alta remoção de palha desequilibre o ambiente edáfico e reduza o fornecimento de C para os microrganismos, diminuindo a atividade microbiana e consequentemente a taxa de decomposição da palha. O manejo de remoção afetou a taxa de decomposição da palha, a menor taxa de decomposição foi associada a maiores remoções. A perda de C e N foi duas e três vezes maior no segundo ano do que no primeiro ano de condução do experimento, respectivamente. Em geral, a celulose da palha diminuiu em 13%, a hemicelulose em 7% e a lignina proporcionalmente enriqueceu em 92% após dois anos. Mundancas na composição química da palha ao longo do processo de decomposição foram detectadas tanto utilizando o método tradicional, via extrações químicas sequenciais, quanto atravéz de técnica espectroscópica, como o Diffuse Reflectance Infrared Fourier Transform DRIFT. Assim, para verificar alterações da celulose e da hemicelulose da palha suger-se o uso das picos espectrais de 896, 987, 1173 e 1447 cm-1, enquanto que para verificar mudanças na lignina os valores de 1510 cm-1 mostrou-se um eficiente preditor. A comunidade bacteriana do solo foi afetada pelo tempo de decomposição. A qualidade da palha explicou 23,2% da variação bacteriana total, onde a hemicelulose representou 17,2% dessa variação. Além disso, a estrutura bacteriana foi sutilmente afetada pelo manejo de remoção da palha da cana-de-açúcar. No geral, nosso estudo mostrou que a remoção de palha para a produção de etanol 2G e bioeletricidade afetará a dinâmica da decomposição da palha nas áreas comerciais de cana-de-açúcar do Brasil. O tempo foi o principal regulador das mudanças nos conteúdos bioquímicos da palha e na estrutura bacteriana do solo. O uso de resíduos de culturas para fins energéticos é uma das principais alternativas para aumentar a produção de bioenergia nos próximos anos. No entanto, a remoção da palha de cana-de-açúcar deve ser feita com prudência, uma vez que a taxa de remoção afetou a dinâmica da decomposição e conseqüentemente deverá afetar a ciclagem de nutrientes e o ciclo do C.
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Richter, Robin [Verfasser], Stephan [Akademischer Betreuer] Huckemann, Stephan [Gutachter] Huckemann, and Gerlind [Gutachter] Plonka-Hoch. "Cartoon-Residual Image Decompositions with Application in Fingerprint Recognition / Robin Richter ; Gutachter: Stephan Huckemann, Gerlind Plonka-Hoch ; Betreuer: Stephan Huckemann." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1201549256/34.
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Yanni, Sandra. "Crop residue composition and decomposition in transgenic corn agroecosystems: effects of bacillus thuringiensis gene and herbivory." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103693.
Abstract:
Bt (Bacillus thuringiensis) corn (Zea mays L.) is reported to have a higher lignin concentration and be more resistant to degradation compared to conventional non-Bt (NBt) hybrids. NBt hybrids are physically affected by the European corn borer (ECB, Ostrinia nubilalis H.), which could increase the deposition of 'stress lignin' in injured tissues and alter the decomposability of corn residue. The objective of this thesis is to test the compositional differences between Bt and NBt corn in terms of fiber, C, and N concentrations and study the decomposition of these residues. The natural variation in lignin between plant parts was also considered to affect the decomposition of corn residue. Field experiments that included 18 Bt and NBt hybrids not infested by ECB showed similarity in lignin and aboveground biomass. Stems from a field-grown Bt hybrid decomposed faster than the NBt near-isoline. In the greenhouse, ECB-infested NBt corn sustained injury, which resulted in lower stem biomass and higher stem N concentration in injured plants. ECB injury did not affect the lignin concentration in stems and CuO oxidation analysis revealed that ECB injury reduced the amount of lignin-derived phenols in stems, which refutes the hypothesis that NBt corn would respond to ECB injury by depositing 'stress lignin'. Infested and non-infested stems buried in the field for five months showed no difference in decomposition due to the Bt gene or herbivory. However, there was 87% more syringic acid in injured NBt stems suggesting that herbivory may enhance lignin decomposition in the longer-term. Under controlled conditions, a 36-week incubation experiment confirmed that Bt and NBt corn tissue decompose at a similar rate, with variation in decomposition rates attributed to the lignin and N concentration in corn tissues. Soils amended with roots (6.2% lignin) produced significantly lower CO2 than stems (3.5% lignin) and leaves (3.2% lignin). In conclusion, the Bt gene and ECB infestation do not affect the chemical composition of corn tissue and should not have an effect on residue decomposition in Bt corn agroecosystems. Due to their elevated lignin concentration, corn roots can make an important contribution to the stabilization of C in the soil.Le maïs Bt (Bacillus thuringiensis - Zea mays L.) est reconnu contenir plus de lignine et être plus résistant que les maïs hybrides conventionnels (NBt). Ces derniers sont affectés par la pyrale du maïs (European Corn Borer ou ECB, Ostrinia nubilalis H.), qui peut augmenter le dépôt de «lignine causée par le stress» dans les tissus et changer la décomposition des résidus de maïs. L'objective de cette thèse est d'évaluer les différences de composition en fibres, C et N entre les maïs BT et NBt, et d'étudier l'effet de l'herbivorie par ECB sur la décomposition les différentes parties résiduelles du plant. Les expériences menées au champ ont démontré que la biomasse aérienne et le contenu en lignine étaient similaires entre 18 hybrides des types BT et NBt non infestés par l'ECB. Toutefois, les tiges des maïs Bt ont présenté une vitesse de décomposition plus élevée. En serre, les tiges de maïs NBt infesté et meurtri par l'ECB, ont montré une plus faible biomasse et une plus grande concentration en N. Toutefois, les blessures engendrées par l'ECB n'ont pas affectés la concentration de lignine dans les tiges. L'analyse par oxydation au CuO a démontré que les blessures ont réduit la quantité de phénols dérivés de la lignine réfutant ainsi l'hypothèse que le NBt répond aux meurtrissures de l'ECB en produisant un dépôt de lignine. Suite à une décomposition sous terre de cinq mois, aucune différence significative due à la présence du gène Bt ou non, n'a été mesurée entre les tiges infestées et non-infestées. Cependant, il y avait 87% plus d'acide syringique dans les tiges de NBt infestées à l'ECB, ce qui suggère que l'herbivorie pourrait améliorer la décomposition à long terme. Dans des conditions contrôlées, une expérience d'incubation de 36 semaines a confirmé que les maïs Bt et NBt se décomposent à la même vitesse; les différences observées étant dues au contenu en lignine et N dans les tissus. Les sols fertilisés avec les racines (6.2% lignine) ont produit beaucoup moins de CO2 que les tiges (3.5% lignine) et les feuilles (3.2% lignine). En conclusion, le gène du Bt ainsi que l'infestation par l'ECB n'affectent pas la composition chimique des tissus de maïs et ne devraient pas affecter la décomposition des résidus de culture. Dû à leur contenu en lignine élevé, les racines de maïs peuvent contribuer de manière importante à la stabilisation du C dans le sol.
17
Kamota, Agathar. "Effect of BT maize on earthworm activity, silage quality and residue decomposition in the central Eastern Cape." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/413.
Abstract:
There are concerns that genetic modification of maize with Bacillus thuringiensis may influence its structural and chemical composition which, together with the Cry1Ab proteins, may affect agro-ecosystem processes and feed quality. This study was aimed at investigating the expression of Cry1Ab protein in leaves, stems and roots of Bt maize and the effect of genetic modification (MON810) on activity of earthworms, silage quality and decomposition of residues in the field. In 2009/10 four maize cultivars; DKC61-25B, DKC61-24, PAN6Q-321B and PAN6777 were planted. Expression of Cry1Ab in leaves, stems and roots was analyzed at 6, 8, 10 and 12 weeks after planting (WAP). Earthworms were also sampled from the same treatments at 6, 9 and 18 WAP. Two silage experiments were conducted using maize cultivars, DKC80-12B and DKC80-10 produced in the 2008/09 season and DKC61-25B, DKC61-24, PAN6Q-321B and PAN6777, produced in 2009/10. The silage was sampled at 0, 2, 4, 8, 15 and 42 days in 2008/09 and 0, 8 and 42 days in 2009/10 and analyzed for Ash Free Dry Matter, Crude Fiber, Neutral Detergent Fiber, Acid Detergent Fiber, Acid Detergent Lignin, Crude Protein and Total Digestible Nutrients. Two litter-bag decomposition studies were also carried out (i) in 2008 (surface applied) using maize cultivars DKC80-12B, DKC80-10 and DKC6-125 residues and (ii) in 2009 (soil incorporated) using DKC75-15B, CRN3505, PAN6Q-321B v and PAN6Q-121. Ash-free dry matter and Cry1Ab protein were measured throughout the incubation time. There were no differences between DKC61-25B and PAN6Q-321B in terms of expression of Cry1Ab in leaves, stems and roots over time. The Cry1Ab expression levels were in decreasing order: leaves > stems > roots. No effects of Bt maize on earthworm numbers and biomass were observed. There were no differences in all silages parameters except NDF and ADF, which were higher in the Bt maize silage than that of the non-Bt maize from the 2008/09 season. The Cry1Ab levels were essentially not reduced during ensiling. The maize residues (both Bt and non-Bt maize) degraded to similar levels, either when surface-applied or incorporated into soil but soil-incorporated residues decomposed faster than surface-applied ones. Cry1Ab degraded as the plant matrix decomposed. The findings suggested that maize genetically modified with the Bt MON810 event can be grown in the Central Eastern Cape without affecting earthworm numbers and biomass, silage quality and decomposition of maize residues.
18
Havel, Tomáš. "Uplatnění statistických metod při zpracování dat." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2010. http://www.nusl.cz/ntk/nusl-222576.
Abstract:
This master’s thesis engages in elaborating the chosen ratio indicators of the two competing companies, elaborating time series out of these indicators and their equation. The prognosis of the future development will be determined based on these indicators and the suggestions will be formulated for eventual issues.
19
Lynch, Madalyn Josephine. "A Measurement of Conservation Agriculture’s Effect on Nitrogen and Carbon Mineralization Rates for Agricultural Recommendations in Haiti’s Central Plateau." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51620.
Abstract:
Much of Haitian agriculture is characterized by subsistence farming systems on eroded and nutrient-poor soils. Implementation of Conservation Agriculture systems has proven effective at improving soil quality and crop yield in many areas of the world, including areas similar to those in Haiti. While most Haitian smallholder farmers are highly resource-limited and adoption of new technologies is limited, these farmers are known to adopt new crops and practices if benefits that outweigh risks are demonstrated. Cover crops that help provide soil cover and increase nutrient mineralization are one of the most potentially beneficial changes that could be made on most smallholder farms. However, before specific cover crop recommendations can be made, their potential benefits need to be quantified. One field experiment in the summer of 2013 assessed decomposition rates and nutrient mineralization from common cash crops and two potential cover crops either on the soil surface or buried at 15 cm. The relative difficulty and expense of conducting these types of field trials led to the development and assessment of a laboratory-based system that could be used to simulate plant residue decomposition and nutrient release under controlled conditions. Additional benefits of a laboratory-based study include the ability to test significantly more treatment combinations than would likely be possible under field conditions and to control nearly all other experimental variables, other than the desired treatment comparisons.Master of Science
20
Wang, Yipeng. "Estimation d’erreur a posteriori pour des calculs de structure électronique par des méthodes ab initio et son application pour diminuer le coût de calcul." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS656.
Abstract:
La thèse porte sur l'analyse des erreurs dans le calcul de la structure électronique. L'objectif à long terme est, d'une part, de dériver un estimateur d'erreur a posteriori calculable pour les méthodes ab initio et, d'autre part, de proposer une stratégie de coût de calcul quasi-optimale pour le calcul numérique de ces méthodes basée sur l'estimation d'erreur a posteriori et la séparation des sources d'erreur de discrétisation et d'itération.Dans la première partie de la thèse, nous introduisons une nouvelle analyse de bien posé pour la méthode de cluster couplé à référence unique basée sur l'inversibilité de la dérivée CC. Sous l'hypothèse minimale que la fonction propre recherchée est normalisable de façon intermédiaire et que la valeur propre associée est isolée et non dégénérée, nous prouvons que les équations CC continues (en dimension infinie) sont toujours bien posées localement. Sous les mêmes hypothèses minimales et à condition que la discrétisation soit suffisamment fine, nous prouvons que les équations CC discrètes sont localement bien posées, et nous dérivons des estimations d'erreur basées sur les résidus avec des constantes positives garanties.La deuxième partie de la thèse se concentre sur l'application de l'estimation d'erreur a posteriori pour construire un chemin quasi-optimal lors de l'approximation de la solution d'EDP. Nous appliquons d'abord une méthode probabiliste pour explorer un chemin optimal pour la résolution numérique de problèmes elliptiques linéaires et non linéaires en minimisant le coût de calcul. Sur la base de l'analyse de ces chemins optimaux, nous proposons deux stratégies quasi-optimales pour atteindre une précision donnée, basées sur la décomposition des sources d'erreur de l'estimateur d'erreur. Enfin, nous validons la faisabilité de ces stratégies quasi-optimales en les appliquant à l'approximation numérique du problème des valeurs propres, c'est-à-dire l'équation de Gross-PitaevskiiThe thesis is concerned with the error analysis of electronic structure calculation. The long term goal is to, in one hand, derive computable a posteriori error estimator for ab initio methods and, in the other hand, propose near-optimal computational cost strategy for the numerical calculation of those methods based on the a posteriori error estimation and the separation of the discretization and iteration error sources.In the first part of the thesis, we introduce a new well-posedness analysis for the single reference coupled cluster method based on the invertibility of the CC derivative. Under the minimal assumption that the sought-after eigenfunction is intermediately normalisable and the associated eigenvalue is isolated and non-degenerate, we prove that the continuous (infinite-dimensional) CC equations are always locally well-posed. Under the same minimal assumptions and provided that the discretization is fine enough, we prove that the discrete Full-CC equations are locally well-posed, and we derive residual-based error estimates with guaranteed positive constants.The second part of the thesis focus on the application of a posteriori error estimation to construct near-optimal path when approximating the solution of PDEs. We firstly apply a probabilistic method to explore an optimal path that minimizes the cost for the numerical resolution of linear and nonlinear elliptic source problems. Based on the analysis of those optimal paths, we propose two near-optimal strategies to achieve a given accuracy based on the error sources decomposition of the error estimator. Finally, we validate the feasibility of those near-optimal strategies by applying them to the numerical approximation of a nonlinear eigenvalue problem, i.e., the Gross-Pitaevskii equation
21
Shahbaz, Muhammad Verfasser], Yakov [Akademischer Betreuer] [Kuzyakov, Andrea [Gutachter] Carminati, Felix [Gutachter] Heitkamp, and Evgenia [Gutachter] Blagodatskaya. "Crop residue decomposition and stabilization in soil organic matter / Muhammad Shahbaz ; Gutachter: Andrea Carminati, Felix Heitkamp, Evgenia Blagodatskaya ; Betreuer: Yakov Kuzyakov." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1125712996/34.
22
Ouyang, Guang. "Study of the variability in brain potentials and responses : development of a new method for electroencephalography (EEG) analysis - residue iteration decomposition (RIDE)." HKBU Institutional Repository, 2013. https://repository.hkbu.edu.hk/etd_ra/1529.
23
Rosa, Neto Lethícia. "Dinâmica do nitrogênio-15N de palha de arroz, soja e sorgo em dois solos de várzea." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/5631.
Abstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe use of alternative crops to rice (Oryza sativa L.), such as soybean (Glycine Maxl.) and sorghum (Sorghum bicolor L.) in lowland areas changes the chemical characteristics of the straw returned to soil. Straw quality and management type are among the main factors that control decomposition rates and straw-N transformations in soil. The objectives of this study were: 1) to compare N dynamics from rice straw decomposition incorporated in soil or on soil surface for two lowland soils; and 2) to assess the effects of straw quality (comparison of rice, soybean and sorghum straw decomposition) and of soil texture on N dynamics during straw decomposition on soil surface. A 180-days greenhouse incubation was carried out at the Federal University of Santa Maria, using rice (Oryza sativa L.), soybean (Glycine max L.) and sorghum (Sorghum bicolor L.) 15N-enriched straws on two lowland soils, one PLANOSOIL (PlaAr) and one Albaqualf Eutrophic gleysoil (PlaGl). Rice straw decomposition was followed both on soil surface and incorporated in soil, while sorghum and soybean straw decomposition was only studied on soil surface. Remaining 15N-straw, 15N-total, soil mineral 15N and soil mineral N were measured after 30, 90 and 180 days of incubation. Rice straw incorporation compared to its maintenance on soil surface increased the release of N from the straw and the amount of soil organic N , yet did not affect the amount of N recovered (straw + soil). For both management modes, soil type did not influence the release of N and C in the rice straw recovered. Regardless of the management mode, soil type only affected the amount of organic N in the soil, with higher value in PlaGl soil than PlaAr soil. Grasses straw (rice and sorghum), with lower N content (higher C: N), led to lower amount of N released, but provided similar amount of organic N in both soils compared to legume straw (soybean). After 180 days, the amount of N recovered (straw + soil) was affected by the interactions between straw and soil types, with higher value in PlaGl soil with grasses straw than with legume straw. For PlaAr soil, the amount of N recovered did not differ between the three straws.
O uso de culturas alternativas ao arroz (Oryza sativa L.), como a soja (Glycine max L.) e o sorgo (Sorghum bicolor L.), em áreas de várzea resultará na adição ao solo de diferentes palhas com características químicas distintas. A qualidade das palhas e o tipo de manejo adotado estão entre os principais fatores que controlam as taxas de decomposição e as transformações do N das palhas no solo. Os objetivos desses estudos foram: 1) avaliar a dinâmica do N durante a decomposição da palha de arroz incorporada ou na superfície de dois solos de várzea; e 2) avaliar o efeito da qualidade da palha de arroz, soja e sorgo e da textura do solo sobre a dinâmica do N durante a decomposição das palhas na superfície do solo. Foi realizada uma incubação com duração de 180 dias em casa de vegetação na Universidade Federal de Santa Maria, utilizando palha de arroz (Oryza sativa L.), soja (Glycine max L.) e sorgo (Sorghum bicolor L.) enriquecidas com 15N em dois solos de várzea, um Planossolo Hidromórfico Eutrófico arênico (PlaAr) e um Planossolo Hidromórfico Eutrófico gleissólico (PlaGl). A palha de arroz foi avaliada na superfície e incorporada aos solos e as palhas de sorgo e soja foram avaliadas apenas na superfície dos solos. Aos 30, 90 e 180 dias foram avaliadas as quantidades de 15N remanescente nas palhas, 15N total e 15N mineral no solo e N mineral no solo. A incorporação da palha comparado a sua manutenção na superfície do solo promove maior liberação de N da palha, maior quantidade de N orgânico no solo e quantidade semelhante de N recuperado (palha + solo). Independente da modalidade de uso, o tipo de solo não influenciou na liberação de N e na quantidade de N recuperado da palha de arroz. Independente da modalidade de uso, o tipo de solo afetou apenas quantidade de N orgânico no solo, sendo os maiores valores encontrados no PlaGl comparado ao PlaAr. As palhas de gramíneas (arroz e sorgo) com menor teor de N (maior C:N) apresentaram menor quantidade de N liberada, mas promoveram quantidade semelhante de N orgânico nos dois solos em relação a palha da leguminosa (soja). Após 180 dias, a quantidade de N recuperado (palha + solo) foi afetada pela interação entre palha e solo, sendo os maiores valores recuperados no solo PlaGl com as palhas de gramíneas do que com a leguminosa. No solo PlaAr a quantidade de N recuperada não diferiu entre as três palhas.
24
Kapal, Debbie B. "Influence of a legume green manure crop on barley straw/stubble decomposition, and soil nitrogen retention and availability." Lincoln University, 2008. http://hdl.handle.net/10182/701.
Abstract:
The incorporation of cereal straw/stubble often immobilises nitrogen (N). This can help conserve N in soil in organic forms, thus reducing loss through leaching over dormant winter periods. However, N-depressions that arise during decomposition can reduce crop yield. The inclusion of a legume green manure can supply fixed-N, thus alleviating the low N availability to crops. In this study, the effect of lupin (Lupinus angustifolius L.) green manure incorporation on barley (Hordeum vulgare L.) straw/stubble decomposition, and N availability was investigated. A field experiment was used to determine the effects of the green manure on decomposition. Decomposition of straw/stubble was monitored using the litterbag technique. Following green manure incorporation, soil cores were incubated in a glasshouse to determine mineral-N availability. Though not significant, the inclusion of lupin green manure seemed to increase the decomposition of straw/stubble during the growth period, then slowing it after its incorporation at 110 d. This was described by a logarithmic pattern of loss of - 4.97 g AFDW residue day⁻¹, with 60% remaining after 140 d. Treatments without lupin had a linear decomposition of - 0.12 g AFDW residue day⁻¹, with 49% remaining after 140 d. The loss of cellulose confirmed the differences in decomposition with the inclusion of lupin resulting in 2.79% less cellulose remaining in straw/stubble after 140 d compared to its exclusion. Lupin significantly increased pot oat N uptake and DM yield by 55 % and 46 %, respectively, compared to its exclusion. However, this effect was not observed in field sown wheat yields and the soil mineral-N measurements made. This study showed that the potential of lupin to increase straw/stubble decomposition by improving the retention and availability of N, leading to long-term yield benefits, needed further investigation.
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Ferreira, Gabriel William Dias. "Resíduos da colheita do eucalipto: ciclagem de nutrientes e uso da espectroscopia do infravermelho próximo para predição da composição química." Universidade Federal de Viçosa, 2012. http://locus.ufv.br/handle/123456789/5492.
Abstract:
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Previous issue date: 2012-06-26Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The demand for eucalypt forests products are high, which leads research to find appropriate management practices to reach higher productions in shorter cycles. The potential nutrient export from harvested plantations raises concern about environmental wood production sustainability. The maintenance of the harvest residues on the field is an alternative to reduce this exportation, returning nutrient to soil in an available form and increasing soil organic matter stocks, which plays a major role in tropical soils quality. These processes are complex and are controlled by a mix of variables related to climate, soil and plant quality. The determination of plants chemical composition is usually done by laborious methods with are both time and reagents consuming. The use of spectroscopy methods can lead to simpler analyses, with results comparable to standard techniques. The aims of this study were to evaluate the nutrient release from the decomposing eucalypt harvest residue and test the viability of the near-infrared spectroscopy (NIRS) to predict its chemical composition. The samples used came from two distinct experiments. Experiment 1: eight treatments defined by a factorial 2x2x2 that included de-barking on field or not, supply of external mineral N or not, and placement of harvest residue (surface or incorporation). They were carried out in 10 Brazilian sites and sampled five times (0, 3, 6, 12 and 36 months) after experiment installation. We determined the contents of Ca, Mg, N, P, K and S. The results showed that there was no influence of external N supply. De-barking on field raised the nutrient stock that remains in the area and accelerates nutrient release from the residue. Incorporation of harvest residues also speeds up nutrient release. The nutrients seemed to behave similarly at the 10 sites evaluated, although the immobilization and mineralization rates were different. In general, K was released faster and Ca was the slowest. Mg, S, N, and P were released in a fairly constant rate, closely linked to biomass loss. For all nutrients evaluated, but K, some immobilization periods were observed. Experiment 2: samples were obtained from a litter bag experiment placed in five eucalypt stands in Southern Bahia. It consisted of four treatments that were the combination of eucalypt harvest residues (leaves + branches or leaves + branches + bark) which came from plants grown under different N supply levels (fertilized and unfertilized with 320 kg ha-1 N), thus having different internal N. Litter bags were collected five times (0, 1, 3, 6 and 12 months) after experiment installation. The content of C, N, Klason lignin, soluble lignin, holocellulose and extractives were determined. We selected 308 samples based on their frequency to test NIRS viability. We tried 21 pre-processing techniques that were combinations of scatter correction and derivatives. In each one we used the principal component analyses (PCA) to identify outliers and define the calibration and validation sets. Using the modified partial least square regression (mPLS) we related the chemical data to the spectra. The models were evaluated using the results of cross validation and external validation. For all characteristics in all stages of decomposition the models were considered efficient whereas for N and extractives the most accurate ones. Using different pre-processing techniques for each characteristic we were able to develop models with better predictive capacity. However, we were able to predict the behavior of all characteristics with good accuracy using just one pre-processing combination (StdMSC 2ndd.), despite the fact that this combination hasn t been identified as the best to each characteristic alone. Therefore, it has been shown that it is feasible to predict the chemical composition of decomposing eucalypt harvest residues by NIRS.
A grande demanda por produtos oriundos das florestas de eucalipto faz com que se busquem formas adequadas de manejá-las, a fim de se obter elevadas produções em ciclos cada vez mais curtos. A grande exportação de nutrientes na colheita dos povoamentos gera preocupações sobre a sustentabilidade do ambiente e da produção dos ciclos subsequentes. A manutenção dos resíduos na área surge como alternativa para minimizar essa exportação, liberar gradualmente os nutrientes à próxima rotação e favorecer os estoques de matéria orgânica do solo (MOS), de papel fundamental nos solos de regiões tropicais. Esses processos são governados por fatores de clima, solo e qualidade do material vegetal. A avaliação da composição do material vegetal é feita por análises químicas trabalhosas e com grande consumo de tempo e reagentes. O uso de métodos espectroscópicos pode tornar esse processo mais simples, com resultados de boa confiabilidade. Os objetivos desse estudo foram avaliar a liberação de nutrientes pela decomposição dos resíduos da colheita do eucalipto e testar a viabilidade da espectroscopia do infravermelho próximo (NIRS) para predizer a composição química dos mesmos. As amostras utilizadas foram obtidas de dois experimentos distintos. Experimento 1: oito tratamentos definidos por um fatorial 2x2x2, sendo presença ou não da casca, com ou sem aplicação de N, mantidos em superfície ou incorporados, coletados em cinco tempos, até três anos em dez locais diferentes do Brasil, distribuídos por quatro estados. Foram determinados os teores de Ca, Mg, N, P, K e S. Não foi observada influência significativa da aplicação de N na liberação de nutrientes. A presença da casca aumentou os estoques de nutrientes na área e acelerou a liberação. A incorporação também aumentou a velocidade de liberação dos nutrientes. Os nutrientes tiveram comportamentos semelhantes nos locais avaliados, contudo, as taxas foram diferentes. Em geral, K foi o nutriente mais rapidamente liberado, enquanto o Ca teve liberação mais lenta. Mg, S, N, e P tiveram liberação mais gradual, tendendo a acompanhar a taxa de decomposição dos resíduos. Para todos os nutrientes, com exceção do K, foram observadas algumas fases de imobilização. Experimento 2: litter bags alocados em cinco povoamentos de eucalipto localizados em regiões distintas do Extremo Sul da BA, sendo quatro tratamentos, resultantes da combinação de resíduos de árvores submetidas ou não a altas doses de N, e presença ou ausência de casca, coletados em cinco tempos, até um ano após a instalação do experimento. Foram determinados os teores de C, N, lignina insolúvel Klason, lignina solúvel, extrativos e holocelulose. Foram selecionadas, com base na distribuição de frequência, 308 amostras que foram utilizadas na análise NIRS. Foram testadas 21 formas de pré-processamento espectral, variando entre a correção do espalhamento e aplicação de derivadas, até o segundo nível. Em cada uma das combinações, aplicou-se a técnica de análise de componentes principais (PCA) para identificar outliers e definir os grupos de calibração e validação. Com uso da mPLS (regressão modificada dos mínimos quadrados parciais) relacionou-se os espectros obtidos com os valores determinados pelos métodos químicos. Os modelos foram avaliados pelos resultados da validação cruzada e validação externa. Os modelos obtidos foram considerados eficientes na predição de todas as características, em todos os tempos, sendo para N e extrativos os mais acurados. Quando se utilizou formas diferenciadas de pré-processamento espectral para cada componente, ajustaram-se modelos com maior capacidade preditiva. O uso de apenas uma forma de pré-processamento (StdMSC 2a d.) possibilitou predizer o comportamento de todos os constituintes avaliados com boa precisão, apesar de não ter sido identificado como a melhor forma de pré-processamento para cada constituinte individualmente. Assim, verificou-se que é viável a utilização do NIRS para predição das transformações sofridas por diferentes componentes dos resíduos da colheita do eucalipto em decomposição.
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Santos, Gabriel de Franceschi dos. "Emissão de óxido nitroso e mineralização do carbono de plantas de cobertura e de dejetos suínos e bovínos em plantio direto de mamona." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/5496.
Abstract:
Conselho Nacional de Desenvolvimento Científico e TecnológicoThe increase in the availability of nutrients to soil microorganisms, especially carbon (C) and nitrogen (N), through crop residues and animal slurries can increase dioxide carbon (CO2) and nitrous oxide (N2O) emissions to the atmosphere. In order, to evaluate this hypothesis, two studies in field conditions were conducted in a typic Hapludalf at experimental area of Soils Department of UFSM-RS. The evaluated treatments were: T1-crop residues (CR) of oat; T2-CR of oat + pig slurry (PS); T3-CR oat + dairy cattle slurry (DCS); T4- CR of oat + N (urea); T5-CR common vetch, T6- CR of mixture between oat+vetch; and T7-fallow. The assessments started soon after the management of cover crops and application of animal slurries. The first study, evaluated the CO2 emission continuously for a period of 99 days. In the second study, it was evaluated the N2O emissions during 322 days. The inclusion of oat in mixture with vetch reduced the C mineralization rate of the CR, which was inversely proportional to the C/N ratio of CR, and followed this order: vetch> oat+vetch> oat. The addition of mineral N with DCS, did not increase the C mineralization of oat straw. The DCS application on the oat straw decreased C mineralization of slurry in relation to their application on the bare soil. The largest N2O fluxes occurred in the first days after the management of cover crops and application of animal slurries. The DCS were organic residue wich promoted greatest cumulative N2O emissions. In favorable conditions for the N2O emission in the soil, the production of this gas seems to be dependent on the C availability in soluble form.
O aumento na disponibilidade de nutrientes aos microrganismos do solo, especialmente de carbono (C) e nitrogênio (N), por meio de resíduos culturais e dejetos de animais pode aumentar as emissões de dióxido de carbono (CO2) e óxido nitroso (N2O) à atmosfera. Com o objetivo de avaliar essa hipótese foram realizados dois estudos em condições de campo, em um Argissolo Vermelho Distrófico arênico, na área experimental do Departamento de Solos da UFSM-RS. Os tratamentos avaliados foram os seguintes: T1- Resíduos culturais (RC) de aveia preta; T2- RC de aveia preta + dejetos líquidos de suínos (DLS); T3- RC de aveia preta + dejetos líquidos de bovinos (DLB); T4- RC de aveia preta + N (uréia); T5- RC de ervilhaca comum; T6- RC do consórcio entre aveia+ervilhaca; e T7- Pousio. As avaliações iniciaram logo após o manejo das plantas de cobertura e da aplicação dos dejetos de animais. No primeiro estudo foi avaliada a emissão de CO2 continuamente por um período de 99 dias. No segundo estudo avaliaram-se as emissões de N2O durante 322 dias. A inclusão da aveia no consórcio com a ervilhaca reduziu a taxa de mineralização do C dos RC, a qual foi inversamente proporcional à relação C/N dos RC, e acompanhou a seguinte ordem: ervilhaca > aveia+ervilhaca > aveia. A adição de N mineral, via DLB, não aumentou a mineralização do C da palha de aveia. A aplicação dos DLB sobre a palha de aveia diminuiu a mineralização do C dos dejetos em relação a sua aplicação em solo descoberto. Os maiores fluxos de N2O ocorreram nos primeiros dias após o manejo das plantas de cobertura e da aplicação dos dejetos de animais. Os DLB foram os resíduos orgânicos que promoveram a maior emissão acumulada de N2O. Em condições favoráveis à emissão de N2O no solo, a produção desse gás parece ser dependente da disponibilidade de C na forma solúvel.
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Martino, Marcelo Gonçalves de. "On the unramified spherical automorphic spectrum." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4017/document.
Abstract:
Cette thèse a deux résultats d'analyse harmonique sur des groupes réductifs. Soit G connexe et défini sur un corps de nombres F, A les adèles et K un sous-groupe compact maximal de G(A). On a étudié la décomposition de l'espace des fonctions de carré intégrable sur le l'espace quotient G(F)\G(A)/K, en tant que module sur une algèbre de Hecke global. Des résultats similaires que ceux obtenus ici ont été établies par divers auteurs pour de nombreux cas particuliers. La caractéristique principale de la présente approche réside dans le fait qu'il est uniforme. Cette approche a été inspirée par des résultats de G. Heckman et E. Opdam dans les problèmes spectraux pour les algèbre de Hecke graduée. Dans la démonstration, nous avons besoin d'un résultat par M. Reeder sur les espaces de poids des représentations (anti)sphériques de la série discrète de l’algèbre de Hecke affine, aussi, nous sommes confrontés au problème du calcul de certains constantes rationnelles dans le spectre global mesurer en termes de mesures de Plancherel locales.Pour le second résultat, nous montrons qu'un complexe de Coxeter et un immeuble euclidienne peuvent être dotés de fonctions de Morse PL qui permet d'écrire des contractions explicites des complexes cellulaires sous-jacents. Cette approche par la théorie de Morse pour étudier les immeubles de Bruhat-Tits a été inspiré par les idées de G. Savin et M. Bestvina dans le cas de l’immeuble de SL(n). Nous conjecturer que ces contractions ont de bonnes bornes sur leurs coefficients et peuvent donc être utilisés pour calculer les groupes Ext entre les représentations tempérée d'une manière analogue à celle qui a été fait par M. Solleveld et E. OpdamThis thesis contains two results on harmonic analysis of reductive groups. First, let G be connected and defined over a number field F, A be the ring of adèles and K be a maximal compact subgroup of G(A). We studied the decomposition of the space of square-integrable functions on the quotient G(F)\G(A)/K, as a module for a global Hecke algebra. Similar results than the ones obtained here have been established by various authors for many special cases of reductive groups. The main feature of the present approach is the fact that it is uniform. Such approach was greatly inspired by results of G. Heckman and E. Opdam in treating spectral problems for graded affine Hecke algebras. In the proof, we need a result by M. Reeder on the weight spaces of the (anti)spherical discrete series representations of affine Hecke algebras, as well as we are faced with the problem of computing certain rational constants factors involved in the global spectral measure in terms of local Plancherel measures which are known only in the affine Hecke algebra context. As for the second result, we show that a Coxeter complex and a Euclidean building can be endowed with piecewise linear Morse functions that allows one to write down explicit contractions of the underlying cell complexes. Such approach via PL Morse theory to study buildings was heavily inspired by ideas from G. Savin and M. Bestvina in the specific case of the building of SL(n). We conjecture that these contractions have nice bounds on their coefficients and thus can be used to compute Ext groups between tempered representations in an analogous way as was done by M. Solleveld and E. Opdam
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Vasconcelos, Ana Luisa Soares de. "Emissão de gases de efeito estufa do solo devido à remoção de quantidades de palha de cana-de-açúcar e à adubação nitrogenada." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-19122016-163327/.
Abstract:
A palha de cana-de-açúcar tem sido uma importante matéria prima para aumentar a produção de bioenergia no Brasil. Porém a dinâmica das emissões de gases de efeito estufa no campo devido à prática de remoção de palha ainda não é totalmente compreendida. O objetivo deste trabalho foi quantificar as emissões de GEE do solo devido à remoção da palha de cana-de-açúcar com e sem adição de nitrogênio. Foram realizados dois experimentos com câmaras amostrais de gás mantidas em condições naturais com quatro tratamentos: sem palha, 3, 6 e 12 Mg ha-1, os quais equivalem as intensidades de 100, 75, 50 e 0% de remoção. O primeiro foi conduzido por 180 dias sem adição de N e o segundo experimento conduzido por 100 dias, foi adicionado 80 kg ha-1 de N no sulfato de amônio e 32 kg ha-1 de N na vinhaça. Conjuntamente ao experimento 1, foi conduzido um ensaio de decomposição com as mesmas quantidades de palha limitadas por caixas plásticas sem fundo (0,3 x 0,5 m). No Experimento 1 a presença de palha aumentou 35 - 45% os fluxos acumulados N2O e CO2 em relação ao solo descoberto. O influxo de CH4 aumentou 40% na presença total de palha (12 Mg ha-1) em relação ao sem palha. O fator de emissão de N2O encontrado para a palha em decomposição foi de 0,02%. No Experimento 2 ocorreu uma intensificação das emissões devido à adubação nitrogenada, com isso as emissões em razão das quantidades de palhas não foram significantes. O fator de emissão médio foi de 0,42%. Os resultados indicam que a palha, sem N, possui um efeito na emissão de GEE e, que para manter o estoque de C do solo, é necessário a manutenção de pelo menos 6 Mg ha-1 para compensar as perdas de CO2 por respiração. Este trabalho contribuirá para os cálculos de pegada de carbono do bioetanol e na decisão da usina sobre a intensidade de remoção de palha de cana-de-açúcar para a produção de energia e etanol 2GSugarcane straw has been point out as an important feedstock to increase bioenergy production in Brazil However, the field greenhouse gas (GHG) emission dynamic due straw removing management is not completely understood yet. Two experiments were conducted with gas sampling chambers that was kept under natural conditions with four treatments: bare soil, 3, 6 and 12 Mg ha-1, which is approximately the equivalent of the 100, 75, 50 and 0 % intensities of removing. The first was conducted for 180 days without the N addition and the second experiment was conducted for 100 day and its was added 80 kg ha-1 N in ammonium sulfate and 32 kg ha-1 N in the vinasse. Parallely to the experiment 1, a decomposing trial was conducted with the same straw amounts in a side limited bottomless plastic boxes (0.3 x 0.5 m). In Experiment 1, the presence of straw increased 35-45% the N2O and CO2 accumulated flux compared to the bare soil. While the influx of CH4 increased by 40% in the maximum straw amount (12 Mg ha-1) compared to zero. The N2O emission factor found for the straw decomposition was 0.02%. In Experiment 2 occurred an intensification of emissions due to nitrogen fertilization which raised the average emission factor for 0.42%. Thus emission due straw quantities were not significant. The results indicate that the straw without N has an effect of GHG emissions, and in order to maintain the C stock in soil is need keep at least 6 Mg ha-1 of straw to compensate for the loss of CO2 thru respiration. This work will contribute to the bioethanol carbon footprint calculation and in the grower decision taking of straw removing intensity for energy and 2G ethanol
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Denega, Genuir Luis. "Emissão de óxido nitroso e dióxido de carbono após aplicação de dejetos de suínos e bovinos em um argissolo." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/5495.
Abstract:
Emission of greenhouse effect gases due to the agricultural use of the dejections of animals as fertilizers, as well as the mineralization of the carbon of those materials in the soil healthy aspects are still relatively a little studied in Brazil. This work was accomplished to evaluate: 1) the annual emission of nitrous oxide with the use, in the corn, of mineral and
organic manuring (pig and cattle slurry and pig deep-bedding); 2) the mineralization of the carbon of pig slurry and of the corn straw, with and without incorporation to the soil. For that two experiments were driven in field conditions, in the period of October of 2007 to September of 2008, in the experimental area of the Departamento de Solos da Universidade Federal de Santa Maria (UFSM) in typic Hapludalf soil. In the first, it was evaluated the emission of N2O periodically for 342 days in the following treatments: T1: without dejections
(control); T2: pig slurry in single application; T3: pig deep-bedding; T4: pig deep-bedding + urea; T5: cattle slurry; T6: pig slurry in parceled out application; T7: without slurry and with mineral fertilizer (NPK) recommended to the corn. Approximately 2/3 of the annual emission of N2O happened during the first 15 days after the application of the organic materials, and all of them provoked increase in the emission of N2O in relation to the control treatment, without use of fertilizers and also in relation to the treatment with the use of N-urea. With the parceled out application of the pig slurry the emission of N2O was inferior to the single application. At the end of approximately one year the factor of emission of N2O in the treatments with application of organic residues varied of 2.1% of applied N with the cattle
slurry to 3.4% of applied N with the pig slurry. In the second experiment the effect of the addition of pig slurry was evaluated on the decomposition of corn straw, with and without incorporation to the soil. For such, the continuous C-CO2 emission was quantified for a period of 158 days in the following treatments: T1: soil without mobilization, T2: mobilized soil, T3: pig slurry in soil surface, T4: pig slurry incorporated, T5: corn straw in surface, T6: incorporate straw, T7: straw + pig slurry in surface and T8: straw + incorporate pig slurry. The incorporation of the corn straw to the soil favored the C mineralization of the straw while in the pig slurry his maintenance in the soil surface favored the C mineralization. The application of pig slurry increased the mineralization straw C in surface in 12% (320 kg ha-1
of added C) and of the incorporate straw in 1.3% (34 kg ha-1 of added C).A emissão de gases de efeito estufa decorrente do uso agrícola dos dejetos de animais como fertilizantes, bem como a mineralização do carbono desses materiais no solo são aspectos ainda relativamente pouco estudados no Brasil. Este trabalho foi realizado para avaliar: 1) a emissão anual de óxido nitroso com o uso, no milho, de adubação mineral e orgânica (dejetos líquidos de suínos e de bovinos e cama sobreposta de suínos); 2) a mineralização do carbono dos dejetos líquidos de suínos e da palha de milho, com e sem incorporação ao solo. Para isso foram conduzidos dois experimentos em condições de campo, no período de outubro de 2007 a setembro de 2008, na área experimental do Departamento de Solos da Universidade Federal de Santa Maria (UFSM) em um Argissolo Vermelho distrófico arênico. No primeiro, avaliou-se periodicamente a emissão de N2O durante 342 dias nos seguintes tratamentos: T1: sem dejetos (testemunha); T2: dejetos líquidos de suínos em aplicação única; T3: cama sobreposta de suínos; T4: cama sobreposta + uréia; T5: dejetos líquidos de bovinos; T6: dejetos líquidos de suínos em aplicação parcelada; T7: sem dejetos e com adubação mineral (NPK) recomendada ao milho. Aproximadamente 2/3 da emissão anual de N2O ocorreu durante os primeiros 15 dias após a aplicação dos materiais orgânicos, sendo que todos eles provocaram aumento na emissão de N2O em relação ao tratamento testemunha, sem uso de fertilizantes e também em relação ao tratamento com o uso de N-uréia. Com a aplicação parcelada dos dejetos de suínos a emissão de N2O foi inferior à aplicação dos dejetos em dose única. Ao final de aproximadamente um ano o fator de emissão de N2O nos tratamentos com aplicação de resíduos orgânicos variou de 2,1 % do N aplicado com os dejetos líquidos de bovinos a 3,4 % do N aplicado com os dejetos líquidos de suínos. No segundo experimento foi avaliado o efeito da adição de dejetos sobre a decomposição de palha de milho, com e sem incorporação ao solo. Para tal, foi quantificada a emissão contínua de C-CO2 por um período de 158 dias nos seguintes tratamentos: T1: solo sem mobilização, T2: solo mobilizado, T3: dejetos líquidos de suínos em superfície, T4: dejetos incorporados, T5: palha de milho em superfície, T6: palha incorporada, T7: palha + dejetos em superfície e T8: palha + dejetos incorporados. A incorporação da palha de milho ao solo favoreceu a mineralização do C da palha enquanto nos dejetos de suínos a sua manutenção na superfície do solo favoreceu a mineralização do C. A aplicação de dejetos líquidos de suínos aumentou a mineralização do C da palha em superfície em 12% (320 kg ha-1 do C adicionado) e da palha incorporada em 1,3% (34 kg ha-1 do C adicionado).
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Hargis, Brent H. "Analysis of Long-Term Utah Temperature Trends Using Hilbert-Haung Transforms." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5490.
Abstract:
We analyzed long-term temperature trends in Utah using a relatively new signal processing method called Empirical Mode Decomposition (EMD). We evaluated the available weather records in Utah and selected 52 stations, which had records longer than 60 years, for analysis. We analyzed daily temperature data, both minimum and maximums, using the EMD method that decomposes non-stationary data (data with a trend) into periodic components and the underlying trend. Most decomposition algorithms require stationary data (no trend) with constant periods and temperature data do not meet these constraints. In addition to identifying the long-term trend, we also identified other periodic processes in the data. While the immediate goal of this research is to characterize long-term temperature trends and identify periodic processes and anomalies, these techniques can be applied to any time series data to characterize trends and identify anomalies. For example, this approach could be used to evaluate flow data in a river to separate the effects of dams or other regulatory structures from natural flow or to look at other water quality data over time to characterize the underlying trends and identify anomalies, and also identify periodic fluctuations in the data. If these periodic fluctuations can be associated with physical processes, the causes or drivers might be discovered helping to better understand the system. We used EMD to separate and analyze long-term temperature trends. This provides awareness and support to better evaluate the extremities of climate change. Using these methods we will be able to define many new aspects of nonlinear and nonstationary data. This research was successful and identified several areas in which it could be extended including data reconstruction for time periods missing data. This analysis tool can be applied to various other time series records.
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Carpinelli, Sandoval. "Ciclagem de macronutrientes em sistemas integrados de produção agropecuária no Centro-Sul do Paraná." Universidade Estadual de Ponta Grossa, 2017. http://tede2.uepg.br/jspui/handle/prefix/2456.
Abstract:
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Os sistemas integrados de produção agropecuária (SIPA) possibilitam sinergismo entre as atividades agrícolas, pecuária e/ou florestal, realizadas na mesma área de cultivo, buscando maximizar os fatores de produção. Modificações no microclima, em SIPA, podem afetar a deposição e a decomposição do resíduo, bem como a liberação e a ciclagem dos nutrientes no sistema de produção. Os objetivos deste trabalho foram: (i) quantificar o aporte dos resíduo e de macronutrientes em SIPA, sob Cambissolo Háplico de textura média, nos Campos Gerais do Paraná; (ii) estimar a taxa de decomposição do resíduo e a liberação de macronutrientes da cultura de soja e da biomassa de forragem anual de inverno (consórcio de aveia preta e azevém anual), em SIPA. O delineamento experimental empregado foi o de blocos completos casualizados com três repetições. Os tratamentos consistiram de combinações de presença de componente arbóreo (eucalipto + grevílea) e doses (90 e 180 kg ha-1) de nitrogênio mineral (ureia – 450 g kg-1 de N) aplicado na pastagem anual de inverno. De modo a melhor representar o ambiente arborizado, foi feita a subdivisão da unidade experimental em cinco distâncias. O experimento foi implantado em 2006; no entanto, as avaliações inerentes a este trabalho foram realizadas no período compreendido entre os meses de dezembro/2014 a outubro/2015. Nesse período foram inseridos aleatoriamente litter bags de resíduo de forragem anual de inverno e de soja, nos tratamentos com ausência e presença do componente arbóreo, respectivamente. As amostragens do material contido nos litter bags foram realizadas aos 7, 15, 30, 60, 90 e 120 dias após a semeadura das culturas (tanto verão quanto de inverno). Foram realizadas as seguintes avaliações: quantidade e qualidade do resíduo vegetais, taxa de decomposição do resíduo vegetal remanescente e de liberação dos macronutrientes (nitrogênio - N, fósforo - P, potássio - K, cálcio - Ca, magnésio - Mg e enxofre - S) dos resíduos, tanto da fase de lavoura como da fase pastagem, ao longo do tempo. A interação entre os fatores avaliados afetou a liberação do S do resíduo do pasto e o K do resíduo de soja. O sistema arborizado, bem como a menor dose de nitrogênio, ocasionou menor massa de resíduo (tanto da pastagem como da lavoura) quando comparado aos demais tratamentos. A quantidade de resíduo da pastagem foi afetada pela distância das árvores. Maiores concentrações dos macronutrientes (K, Ca e Mg) no resíduo da pastagem, ao final do período de pastejo, foram observadas no sistema arborizado. A ausência do componente arbóreo ocasionou maiores concentração de Ca e Mg no resíduo da soja. Além da maior quantidade de massa de resíduo da soja na maior dose de N, tal resíduo apresentava maior concentração em K e S do que a menor dose. Variações na taxa de decomposições de massa seca remanescente dos resíduos da pastagem e soja também foram influenciadas pela distância em relação aos renques arbóreos. A liberação de N, P, K e Mg do resíduo pasto e de P, Mg e S do resíduo da soja não foi influenciada pelos tratamentos. A decomposição do resíduo da pastagem e seu respectivo efeito proporcionou uma maior ciclagem de nutrientes para a soja do que o oposto.
Integrated crop-livestock systems (ICLS) enable synergism between agricultural, livestock and/or forestry activities carried out in the same area, focusing maximization of production factors. Changes in ICLS microclimates can affect the deposition and decomposition of plant residues, as well as macronutrient and nutrient cycling present in the system. The aims of this study were (i) to quantify the contribution of plant residues and macronutrients in ICLS, under loamy-sand Typic Distrudept, in the Paraná Campos Gerais area; and (ii) to estimate the decomposition of the residue and the release of macronutrients from the soybean crop and the biomass of annual winter forage (consortium of black oats and annual ryegrass) in ICLS. The experimental design was a randomized complete block with three replicates. The treatments consisted of combinations of the presence of an arboreal component (eucalyptus + Grevillea) and doses (90 and 180 kg N ha-1year-1) of mineral nitrogen (as urea - 450 g kg-1 N) applied to the annual intercropped pasture. In order to better represent the forested environment, the experimental unit was subdivided into five distances. The experiment was implemented in 2006. However, the evaluations inherent to this study were carried out from December 2014 up to October 2015. During this period, litterbags of a consortium of black oat residues with ryegrass and soybean were randomly inserted in the treatments with the absence and presence of the arboreal component, respectively. Samplings of the material contained in the litterbags were carried out at 7, 15, 30, 60, 90 and 120 days after crop sowing (both in summer and winter). The following evaluations were performed: amount and quality of the plant residue, decomposition rate of the remaining plant residue and macronutrient release (nitrogen - N, phosphorus - P, potassium - K, calcium - Ca, magnesium - Mg and sulfur - S) of the residue, both in the tillage phase and in the pasture stage, over time. The forested system, as well as the lower nitrogen dose, presented lower residue mass (both in the pasture and in the crop) compared to the other treatments. Tree distances also affected the amount of grass residue. The highest mean macronutrient concentrations (K, Ca and Mg) in the pasture residue at the end of the grazing period was observed in the arboreal system. The no-tree system resulted in higher concentrations of Ca and Mg in the soybean residue when compared to the arboreal system. In addition to the greater amount of soybean residue mass at the highest N dose, this residue presented higher N, K and S concentrations compared to the lowest dose. Variations in the decomposition rate of remaining pasture and soybean residue dry mass also occurred as a function of distance from tree trunks. The evaluated factors did not affect the release of P, K and Mg from the pasture residue and P, Mg and S from the soybean residue. The interaction between the evaluated affected S release from the pasture residue and K from the soybean residue. The decomposition of the residue of pasture and its respective effect rovided a greater cycling of nutrients for soybean.
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Pascault, Noémie. "Réponse des communautés microbiennes du sol à l'apport de résidus de culture : influence des pratiques agricoles et lien avec le fonctionnement biologique du sol." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00582567.
Abstract:
A l'échelle de l'agro-écosystème, la productivité primaire est sous la dépendance du recyclage des matières organiques du sol (MOS) par l'action des organismes indigènes décomposeurs, qui minéralisent les composés organiques libérant ainsi les nutriments nécessaires à la croissance végétale. A une échelle plus globale, le recyclage des MOS détermine les flux de carbone entre le sol et l'atmosphère, avec des conséquences majeures sur la qualité de l'environnement et les changements globaux. Malgré le rôle central des microorganismes indigènes dans ces processus, la composante microbienne est encore mal connue et souvent considérée comme une boîte noire en termes de diversité et de fonctionnalité. Par conséquent, pour mieux comprendre et prédire l'évolution des MOS et donc les flux de carbone (C) dans les agro-écosystèmes, il est nécessaire de mieux connaitre les populations et les mécanismes microbiens impliqués dans leur dégradation et transformation. Dans ce contexte, l'objectif de cette thèse était de progresser dans la connaissance de la réponse des communautés microbiennes telluriques à l'apport de résidus de culture. Cette réponse des communautés microbiennes a été abordée en termes de (i) succession des populations impliquées dans les processus de dégradation de ces MOF (matières organiques fraîches), (ii) lien avec leur fonction de dégradation et répercussion sur la dynamique des matières organiques, et (iii) rôle dans les processus de stockage/déstockage du carbone via les processus de " priming effect ". Différents paramètres pouvant moduler la dégradation des résidus et la dynamique des communautés ont été pris en compte : modalité d'apport des résidus (pratiques culturales), qualité biochimique des résidus (différentes espèces végétales), et température. La stratégie globale de recherche développée repose sur des expérimentations de terrain et au laboratoire impliquant différentes échelles spatiales (du microcosme de sol à la parcelle agronomique) et temporelles (du temps de génération microbien aux cycles culturaux). La réponse des communautés microbiennes à l'apport de résidus a été évaluée par l'utilisation de méthodes moléculaires permettant de caractériser sans a priori la diversité des microorganismes du sol (empreintes moléculaires, clonage/séquençage, séquençage haut débit). En parallèle, un suivi quantitatif et qualitatif de la matière organique du sol, par des méthodes de biochimie ou de spectroscopie, a été réalisé afin d'établir le lien entre la dynamique des communautés microbiennes et le devenir de la matière organique dans le sol. Les deux premiers chapitres du manuscrit portent sur des expérimentations réalisées au terrain (conditions naturelles) afin d'évaluer l'influence de la localisation des résidus (résidus de blé incorporés vs. laissés en surface ; site expérimentale INRA Mons) d'une part et d'autre part de la qualité biochimique des résidus (résidus de blé, colza et luzerne incorporés, site expérimentale INRA Epoisses) sur la dynamique des communautés microbiennes du sol. Les résultats obtenus mettent en évidence une forte influence de la localisation comme de la qualité biochimique des résidus sur les successions de populations microbiennes induites suite à l'apport. Des populations/groupes microbiens stimulés spécifiquement dans chaque modalité ont été identifiés. Les résultats de diversité ont été mis en regard des dynamiques de décomposition des résidus, afin de faire le lien entre les successions de populations et l'évolution des ressources trophiques. La troisième partie du travail correspond à une expérimentation en conditions contrôlées (microcosmes de sol) nous permettant de coupler des outils moléculaires et isotopiques (ADN-SIP) pour cibler spécifiquement les populations microbiennes activement impliquées dans la dégradation des résidus de culture - etc
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Rezgui, Cyrine. "Etude du potentiel d'introduction de la culture du pois d'hiver dans les successions culturales en Normandie : conséquences sur les communautés microbiennes du sol et les flux d'azote Impacts of the winter pea crop (instead of rapeseed) on soil microbial communities, nitrogen balance and wheat yield Quantification et analyse des exsudats racinaires de pois, de blé et de colza : mise au point d’une méthodologie de collecte des exsudats racinaires N rhizodeposition quantification and root exudates characterization of pea (Pisum Sativum L.), rapeseed (Brassica napus L.) and wheat (Triticum aestivum L.) under controlled conditions Linking soil microbial community to C and N dynamics during crop residues decomposition." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR047.
Abstract:
La transition agroécologique vise la triple performance agronomique, écologique et sociétale des exploitations agricoles. Un certain nombre de pratiques agricoles permet d’envisager la construction et le développement de systèmes de culture répondant à ces contraintes. Les légumineuses, par leur capacité à fixer l’azote atmosphérique, sont une alternative intéressante aux intrants azotés. Outre l’absence de fertilisation lors de leur culture, elles fournissent de l’azote à la culture suivante. Il existe cependant un manque de références sur certaines légumineuses à graines et notamment la culture du pois d’hiver. En effet, si des données acquises dans différentes régions françaises sont disponibles, aucune référence n’a été publiée pour la Normandie où la culture du pois d’hiver connaît un récent regain d’intérêt. Cette thèse propose d’évaluer, sur une période de deux ans, l’effet du remplacement du colza par le pois d’hiver en tête de rotation en réalisant une analyse comparative de ces deux successions (pois d’hiver-blé et colza-blé). L’objectif était d’évaluer l’effet de ce changement de tête de rotation (pois d’hiver vs colza) sur l’état biologique du sol et les flux d’azote à différentes échelles spatiotemporelles. Les résultats ont révélé une forte variabilité spatio-temporelle dans la réponse des communautés microbiennes du sol, et mis en évidence l’importance du contexte pédoclimatique dans le déterminisme de l’abondance et de l’activité des communautés microbiennes du sol. Ils ont montré par ailleurs, l’effet positif du pois d’hiver sur la disponibilité de l’azote minéral au cours du cycle cultural et pour les cultures suivantes, ici le blé puis l’orge. Les apports d’azote minéral dans le sol lié à la contribution des parties racinaires via la rhizodéposition et à la dégradation des résidus de culture après récolte ont été évalués au cours de ce travail de thèse. En effet, si la rhizodéposition s’est révélée plus importante sous pois d’hiver, elle n’a pas eu d’impact significatif sur les communautés microbiennes rhizosphériques. Contrairement à ces observations, la dégradation des résidus de culture a significativement modifié la composition des communautés bactériennes en lien avec leur composition biochimique initiale. La succession culturale incluant le pois a enrichi le sol en azote minéral mais des risques de perte d’azote par lixiviation de l’ordre de 23 kg N. ha-1 ont été estimés. Ces constats soulignent l’importance d’adapter la conduite des systèmes de culture incluant le pois d’hiver, en limitant les pertes d’azote par lixiviation et en maximisant son utilisation par les cultures suivantes. Les résultats de ces travaux ont confirmé la diminution des quantités d’engrais azoté utilisées dans la succession contenant le pois, sans préjudice de productivité, ni pour le pois, ni pour la culture suivante, ici, le blé. Finalement, introduire le pois d’hiver dans la rotation de culture en région Normandie, semble permettre de répondre à la problématique d’augmentation du coût des intrants, et aux enjeux de transition agroécologique et d’autonomie protéique régionaleThe agroecological transition targets triple agronomic, ecological, and societal performance of farms. Some new agricultural practices had emerged to develop a new cropping system to respond to these constraints. Legumes constitute an interesting alternative. Indeed, legumes are advantageous for soils due to their symbiotic relationship with nitrogen-fixing bacteria. The presence of compatible rhizobia combined to nitrogen-limited conditions promotes symbiosis which is the most efficient way for legumes to acquire more nitrogen. Compared with non-nodulated plants, symbiosis provides a competitive advantage by increasing soil nitrogen pool. However, some grain legumes, notably winter pea, are rarely studied, especially in the Normandy region where no reference has been published for this crop. The objective of this study is to compare two crop successions for a period of two years (winter pea-wheat and rapeseed-wheat), in order to assess the effect of replacing rapeseed by winter pea at the head of the rotation .We evaluated the effect of these two crops (winter pea vs rapeseed) on the biological state of the soil and nitrogen fluxes at different spatio-temporal scales. The results showed a significant spatio-temporal effect on the response of soil microbial communities and highlighted the importance of the pedoclimatic context in determining the abundance and activity of soil microbial communities. A positive effect of winter pea has been demonstrated on the availability of mineral nitrogen during the crop cycle and for following crops (wheat and barley). The supply of nitrogen to the soil is linked to the rhizodeposition of nitrogen via plants roots and the degradation of crop residues after harvest. Our results showed that winter pea exhibited the greatest amount of nitrogen rhizodeposition. However, rhizodeposition did not have a significant impact on rhizospheric microbial communities. Contrary to these observations, the degradation of crop residues significantly modified the composition of bacterial communities linked to their initial biochemical composition. Crop succession including winter pea enriched the soil with mineral nitrogen but simulation with STICS software revealed a nitrogen leaching around of 23 kg N. ha-1 during the cropping cycle. These findings underline the importance of adapting an adequate crop management system, including winter pea, to limit nitrogen losses. The results showed also that wheat yields after winter pea without the use of nitrogen fertilizers were equivalent to those obtained after rapeseed. However, rapeseed required significant nitrogen fertilization. Including winter pea in crop rotation in Normandy region may be a key to enhance productivity, to respond to the challenges of agroecological transition, regional protein autonomy, and to reduce environmental and economic costs, by reducing notably, the costs of fertilizers production and uses
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Richter, Robin. "Cartoon-Residual Image Decompositions with Application in Fingerprint Recognition." Doctoral thesis, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0005-12CB-2.
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Umar, Shariah. "Effect of clay on plant residue decomposition." 2010. http://hdl.handle.net/2440/60392.
Abstract:
Plant residues added to soil are a source of nutrients for plants and soil organisms and increase soil organic matter which has an important role in improving soil structure and fertility, hence maintaining soil quality for sustainable agriculture. In order to utilize plant residues for increasing soil organic matter more effectively, it is necessary to understand the mechanisms of plant residue decomposition. Soil organic matter decomposition is influenced by several factors such as plant residue quality, temperature, water availability, soil structure and soil texture, particularly clay content. The interaction of clay and decomposition of organic matter has been studied in the past. Nevertheless, many studies investigated this interaction in natural soil or under field conditions over long periods of time. Variation in environmental factors may influence the interaction of clay and decomposition of organic matter, thus in most previous studies their effect cannot be separated from the direct effect of clay on decomposition. To study the direct effect of clay on organic matter decomposition, four experiments with different objectives were carried out using isolated natural clay, under controlled conditions (e.g. temperature and organic matter input) and a short incubation period (approximately one month). All experiments were carried out using a sand matrix to which different clay types, clay fractions (natural or with iron oxide partially removed) or clay concentrations were added together with mature wheat straw (C/N 122 in most experiments, except Experiment 2 where the wheat straw had a C/N of 18) and a microbial inoculum. To investigate the effect of clay type, two clay types were added. They were isolated from Wiesenboden (W) and Red Brown Earth (RBE) soil. Clay types from both soils contained kaolinite and illite, but smectite only occurred in W clay. Iron oxide is thought to be important for the binding of organic matter to clay, therefore two clay fractions were used, the clay with native iron oxide (natural clay) and clay from which iron oxide was partially removed by citrate-dithionite-bicarbonate treatment (citrate-dithionite clay, CD clay). The following parameters were measured: pH, water loss, respiration rate, microbial community structure using phospholipid fatty acid analysis and, in some experiments, particulate organic matter. In all experiments, the water content of the substrate mixes was adjusted only at the start; water loss was greatest in the control and decreased with increasing clay content. The aim of the first experiment was to study the effect of the concentration of W clay on decomposition of wheat residues. Respiration (i.e. decomposition of the wheat straw) was affected by clay in two ways (i) decreased decomposition, thus protection of organic matter, in the initial phase at all concentrations (5, 10, 20 and 40%) and throughout the incubation period at ≤ 20% clay, and (ii) greater water retention at higher clay concentration particularly 40% clay that allowed maintenance of higher respiration rates towards the end of incubation. Generally, clay concentration had an effect on microbial community structure but not on microbial biomass. The effect of clay concentration was also investigated in the second experiment, but using RBE clay and a narrower range of concentrations (0, 2.5, 5, 10 and 20% clay) than in the first experiment with W clay. The wheat residue used in this experiment had a lower C/N ratio compared to the other three experiments (C/N 18 compared to 122). In contrast to the first experiment, cumulative respiration of the clay treatments was greater than that of control throughout the incubation, thus clay increased rather than decreased decomposition. This may be due to the properties of the wheat residue used in this experiment which contained more water-soluble compounds, the diffusion of which would be enhanced in treatments with clay compared to the control due to their higher water availability. However, considering only the treatments with added clay, cumulative respiration followed the same pattern as in the first experiment, with highest cumulative respiration at 20% clay. In general, microbial community structure, microbial biomass and microbial groups (i.e. bacterial and fungal fatty acids) were affected by the presence of clay and sampling time, but there was no clear relationship between these factors and the richness and diversity of the microbial community. The aim of the third experiment was to determine the effect of clay concentration (5 and 40% of W clay) and fraction (natural or citrate-dithionite clay) on decomposition of wheat straw and microbial community structure. Clay fraction and concentration strongly affected the respiration rate and microbial community structure as well as microbial biomass but not the concentration of particulate organic matter (POM). Compared to the control, partial removal of iron oxide strongly increased decomposition at both concentrations whereas clay with iron oxides reduced the decomposition. Microbial community structure was affected by clay fractions, particularly at 40% clay. The aim of the fourth experiment was to determine the effect of clay fraction (natural and citrate-dithionite clay) and clay type (W clay or RBE clay) at 5% clay on decomposition of wheat straw and microbial community structure. Clay type and the partial removal of iron oxide had a significant effect on the decomposition rate but did not affect POM concentration. As in the third experiment, partial removal of iron oxide increased respiration rate, the effect was less pronounced in RBE clay than in W clay. Clay type and fraction strongly affected microbial community structure. In conclusion, the experiments showed that native clay generally reduces organic matter decomposition by binding and occlusion. The importance of iron oxide for the protective effect of clay on organic matter decomposition was shown by the fact that partial removal of iron oxide strongly increased decomposition rate compared to the native clay. The two clay types differed in their effect. The W clay containing smectite protects organic matter to a greater extent than RBE clay with predominantly illite and kaolinite due to its higher surface area and CEC that lead to binding and or occlusion. The results also showed that although clay reduces organic matter decomposition under optimal water availability, this effect can be reversed as the substrates dry out because the greater water retention of substrates with clay concentrations > 10% compared to the pure sand matrix allows maintenance of a greater microbial activity. Clay type, fraction and concentration affected microbial community structure via their effect on organic matter and water availability.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1521949
Thesis (M.Ag.Sc.) -- University of Adelaide, School of Earth and Environment Science, 2010
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Duong, Tra Thi Thanh. "Dynamics of plant residue decomposition and nutrient release." 2009. http://hdl.handle.net/2440/59393.
Abstract:
Proper management of soil organic matter (SOM) contributes to increasing plant productivity and reducing dependency on mineral fertilizers. Organic matter is widely regarded as a vital component of a healthy soil as it plays an important role in soil physical, chemical and biological fertility. Plant residues are the primary source of SOM. Therefore, proper SOM management requires a better understanding of plant residue decomposition kinetics in order to synchronize nutrient release during decomposition and plant uptake and prevent nutrient losses. In natural and managed ecosystems, residues are added frequently to soil, in the form of dead roots and litter fall of plant species with different C/N ratios. However, in most studies on residue decomposition, residues with different C/N ratios are added once and the effect of the presence of plants on residue decomposition is rarely investigated. In this project, four experiments were carried out with different objectives in order to close these knowledge gaps. The aim of the first experiment was to investigate the effect of frequent wheat residue addition on C mineralization and N dynamics. The experiment consisted of five treatments with different frequency of residue addition (2% w/w of wheat residues in total): once (100%W), every 16 days (25%), every 8 days (12.5%) or every 4 days (6.25%) and noresidue addition (control) with four replicates. The results showed that increasing frequency of low-N wheat residue addition increased C mineralization. Compared to 100%W, cumulative respiration per g residue at the end of the incubation (day 80) was increased by 57, 82 and 92% at 25%W, 12.5%W and 6.25%W, respectively. Despite large increases in cumulative respiration, frequent residue addition did not affect inorganic N or available N concentrations, microbial biomass C and N or soil pH. It is concluded that experiments with single residue additions may underestimate residue decomposition rates in the field because with several additions, soil microbes respire more of the added C (and possibly native soil C) per unit biomass but that this does not change their N requirements or the microbial community composition. In the second experiment, the effect of mixing of high and low C/N residues at different times during incubation was investigated. There were 4 addition times; 25% of a total of 2% (w/w) residue was added either as wheat (high C/N) or lupin (low C/N) residue. Wheat residue was added to lupin residues on days 16 (LW-16), 32 (LW-32) or 48 (LW-48). Additional treatments were 100%L (added 25% of lupin residues on days 0, 16, 32 and 48) and 100%W (added 25% of wheat residues on days 0, 16, 32 and 48) and 0% (the control) with four replicates. Adding high C/N residues into decomposing low C/N ratio residue strongly decreased the respiration rate compared to the addition of low C/N residues, and lowered the availability of inorganic N, but significantly increased soil pH and altered microbial community composition. By the end of the incubation on day 64, the cumulative respiration of LW-16, LW-32 and LW-48 was similar and approximately 30% lower than in the treatment with only lupin residue addition. The third experiment studied the effect of spatial separation of high and low C/N residues on decomposition and N mineralization. Each microcosm consisted of two PVC caps of 70 mm diameter and 20 mm height with the open end facing each other separated by a 30μm mesh. The caps were filled with soil mixed with either low or high C/N residue with three replicates. Contact of high and low C/N residues led to an increase in the decomposition rate of the high C/N residues at the interface whereas it decreased it in the low C/N residues. The results showed that N and soluble C compounds moved from the easily decomposable residues into the surrounding soil, thereby enhancing microbial activity, increasing inorganic N and significantly changing soil pH in the layer 0-5 mm from the interface compared to the 5-10 mm layer of the high C/N residues, whereas the movement of soluble C and N to high C/N residues decreased the decomposition of the low C/N residues. The final experiment investigated the effect of living plants on decomposition of high and low C/N residues. Wheat was grown in pots with a 30 μm mesh at the bottom. After a root mat had formed (>50% root coverage), a PVC cap with soil with high and low C/N residues (2% w/w) was placed against the mesh. The presence of plant roots significantly increased the respiration rate, N immobilization and increased the soil pH in the 0-5 mm layer in the first 4 days compared to the 5-10 mm layer. This enhanced microbial activity (and probably microbial biomass) can be explained by root exudates. The microbial community composition of plant treatments differed significantly from treatments without plants and the effect was greater in the immediate vicinity of the roots.Thesis (M.Ag.Sc.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009
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Shahbaz, Muhammad. "Crop residue decomposition and stabilization in soil organic matter." Thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-002B-7D38-E.
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Hasbullah, Hasbullah. "Alleviating the negative effect of salinity on soil respiration by plant residue addition: effect of residue properties, mixing and amendment frequency." Thesis, 2015. http://hdl.handle.net/2440/102766.
Abstract:
Salinity is a major constraint to crop production and also contributes to land degradation, particularly in arid and semiarid regions. Salinity has negative effects on soil microorganisms, reducing soil respiration, microbial biomass and microbial diversity. One of the main reasons for the negative impact of salinity is the low osmotic potential induced by high salt concentrations in the soil solution which reduces water uptake into cells and can cause water loss from cells. Some microorganisms can adapt to salinity by accumulation of osmolytes which is a significant metabolic burden. Rapidly decomposable plant residues contain high concentrations of easily available compounds which can be utilised by many soil microbes. Slowly decomposable residues on the other hand contain complex compounds which can only be utilised by few microbes, those capable of releasing specialised enzymes to break down these compounds. If salinity inhibits or kills some microbes, the decomposition of rapidly decomposable residues may be less affected than that of slowly decomposable residues because the loss of sensitive microbes can be compensated by a larger number of microbes with the former compared to the latter. If this is true, microbial activity after addition of slowly decomposable residues (high in lignin content and C/N ratio and low in water soluble carbon) should decrease more strongly with increasing salinity than after addition of rapidly decomposable residues. However, most previous studies on respiration in saline soils only used one or two types of plant residues (e.g. cereal or legume shoots). A further factor that may influence the impact of salinity on soil respiration is the frequency of residue addition. Frequent residue addition may provide soil microbes with a continuous supply of nutrients and therefore improve salinity tolerance compared to a single addition where easily available compounds are rapidly depleted. These two assumptions have not been systematically investigated.
The aim of this project was to investigate the effect of the chemical composition of added residues, mixing of residues and addition frequency on soil respiration and microbial biomass in soils with different salinity. Three studies were carried out to address the aims in non-saline soil and naturally saline soils with different salinity levels. The aim of the first study was to investigate the impact of salinity on respiration in soil amended with residues differing in chemical composition (lignin concentration, water soluble organic carbon and C/N ratio). Three incubation experiments were conducted in this study. In the first experiment various residue types (shoots of wheat, canola, saltbush and kikuyu, saw dust, eucalyptus leaves) differing in C/N ratio, lignin and water extractable organic carbon concentration, were applied at 2% w/w to a non-saline soil (EC₁﹕₅, 0.1 dS m⁻¹) and three naturally saline soils with EC₁﹕₅ 1, 2.5 and 3.3 dS m⁻¹. Cumulative respiration decreased with increasing salinity but the negative effect of salinity was different among residues. Compared to non-saline soil, respiration was decreased by 20% at EC₁﹕₅ 0.3 dS m⁻¹ when slowly decomposable residues (saw dust or canola shoots) were added, but at EC₁﹕₅ 4 dS m⁻¹ when amended with a rapidly decomposable residue (saltbush). In the second experiment, the influence of residue C/N ratio and lignin content on soil respiration in saline soils was investigated. Two residues (canola and saw dust) with high C/N ratios but different lignin content were used. The C/N ratio was adjusted to between 20 and 80 by adding ammonium sulfate. Increasing salinity had smaller impact on cumulative respiration after addition of residues with C/N ratio 20 or 40 compared to residues with higher C/N ratio. In the third experiment, the effect of the concentration of water-soluble organic C (WEOC) of the residues was determined. WEOC was partially removed by leaching from two residues with high WEOC content (eucalypt leaves and saltbush shoots). Partial WEOC removal decreased cumulative respiration in saline soil compared to the original residues, but increased the negative effect of salinity on respiration only with saltbush shoots. The second study was conducted using the four soils from the first study (EC₁﹕₅, 0.1, 1, 2.5 and 3.3 dS m⁻¹) to compare the impact of single and multiple additions of residues that differ in decomposability on the response of soil respiration to increasing salinity. Two residues with distinct decomposability were used; kikuyu with 19 C/N ratio (rapidly decomposable) and canola with 82 C/N ratio (slowly decomposable). Both residues were added once or 2-4 times (on days 0, 14, 28 and 42) with a total addition of 10 g C kg⁻¹ soil and incubated for 56 days. Compared to a single addition, repeated addition of the rapidly decomposable residue reduced the negative effect of salinity on cumulative respiration, but this was not the case with slowly decomposable residues. The third study was carried out to investigate the effect of the proportion of rapidly and slowly decomposable residues in a mixture on the impact of salinity on soil respiration. This study included two experiments with two residues differing in decomposability (slowly decomposable saw dust and rapidly decomposable kikuyu grass). In the first experiment, both residues were added alone and in mixtures with different ratios into four soils having EC₁﹕₅ 0.1, 1.0, 2.5 and 3.3 dS m⁻¹. The addition of 25% of rapidly decomposable residues in mixture with slowly decomposable residues was sufficient to decrease the negative impact of salinity on cumulative respiration compared to the slowly decomposable residue alone. In the second experiment, three soils were used (EC₁﹕₅ 0.1, 1.0 and 2.5 dS m⁻¹), residues were added once or 3 times (on days 0, 14 and 28) to achieve a total of 10 g C kg⁻¹ soil either with sawdust alone, kikuyu alone or both where final proportion of kikuyu was 25%, but the order in which the residues were applied differed The negative effect of salinity on cumulative respiration was smaller when the rapidly decomposable residue was added early, that is when the soil contained small amounts of slowly decomposable residues. Salinity reduced soil respiration to a greater extent in treatments where rapidly decomposable residue was added to soil containing larger amounts of slowly decomposable residues. It is concluded that rapidly decomposable residues can alleviate salinity stress to soil microbes even if they make up only a small proportion of the residues added. By promoting greater microbial activity in saline soils and providing nutrients, rapidly decomposable residues could also improve plant growth through increased nutrient availability.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Agriculture, Food and Wine, 2015.
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Iqbal, Shahriar Mohammod. "Effect of crop residue qualities on decomposition rates, soil phosphorus dynamics and plant phosphorus uptake." Thesis, 2009. http://hdl.handle.net/2440/49812.
Abstract:
Phosphorus (P) is an essential plant nutrient that may limit plant growth and agricultural productivity if not available for crop plant uptake in sufficient quantities at the time required. Many Australian soils are deficient in available P, despite a long history of P fertilizer application, and this is due to fertilizer P rapidly becoming unavailable largely through biochemical fixation. The resulting low P fertilizer efficiency, coupled with rapidly rising cost of fertilizers, has increased interest in biological cycling of P from sources such as crop residues. However, to date, much of the Australian research has focussed on soils with relatively high organic matter content (> 2%) and relatively heavy texture i.e. medium to high clay content. Furthermore, although there is information on pasture residue decomposition and P release for sandy soils with low organic matter in Australia, a recent shift to continuous cropping systems means that information for a range of crop residues is required but is not currently available. Therefore the aims of the work described in this thesis were to (i) increase the efficiency of P use when crop residue P are applied to crops and (ii) determine the effect of crop residue biochemical quality on decomposition rates, soil P dynamics and plant P uptake in light textured sandy soils with low organic matter which are typical of a large proportion of the southern Australian wheat growing area. A further aim was to investigate the effects of combined additions of plant residue and P fertilizer on P cycling in these soils, a scenario highly relevant to farming systems.
A series of soil incubation and plant growth experiments were undertaken to characterize P dynamics in soil following addition of a wide range of crop residues (total 15) collected from agricultural sites throughout South Australia. The residues, differing in age and biochemical quality, were young shoots of canola, lupin, pea, lucerne and lentil; mature shoot residues of canola, lupin, pea and wheat and mature root residues of wheat, canola and lupin. The concentration of total and water soluble P, C, and N in the residues was measured using standard wet chemical analyses and the carbon chemistry was determined by NMR spectroscopy. Decomposition of crop residues was continuously monitored over a period of up to 140 days by measuring soil respiration. Available P and microbial biomass P and C were also assessed at different times during the incubations. The total P in residues ranged from 0.16% to 0.32% and 0.05% to 0.08% in young and mature shoots, respectively. Water-soluble P was related to residue total P and ranged from 29% to 81% and 13% to 29% of total P in young and mature shoots, respectively. The C: P ratio ranged from 133: 1 to 253: 1 and 504: 1 to 858: 1 in young and mature shoots, respectively.
Phosphorus availability and microbial P uptake differed between soils amended with crop residues and soluble P fertilizer as triple super phosphate (TSP). Soil respiration rates were significantly higher in soils amended with crop residues than in the soils amended with TSP or the unamended control in the first 58 days of incubation. In an experiment in which residues and TSP were added at a rate of 10 mg P kg⁻¹, available P was greater for TSP than residue-amended soil, whereas microbial P showed the opposite trend. Respiration rate and microbial P were positively correlated with C addition rate, which was highest in mature wheat residue because it had the lowest P concentration. In order to assess when P released from the residues is available for plants, wheat was grown over three consecutive crop periods with each period lasting for 4 weeks. Young residues with high content of water soluble P, C, N and amide and low lignin and phenolic content decomposed faster than mature residues. The C type and amount added with residues controlled the dynamics of P availability. Surprisingly, canola mature root increased available P and plant growth as much as young shoot residues while root residues of wheat and lupin resulted in P immobilization and low plant growth. Compared to canola young shoot, canola mature root has a higher total P concentration and a lower C: P ratio. Plant P uptake was positively correlated with residue total and water-soluble P content and negatively correlated with residue C: P and C: N ratio and amount of C added with the residues. In another experiment where residue was added at 2.5 g C kg⁻¹ soil and compared with TSP (4 and 10 mg P kg⁻¹ soil), available P and plant P uptake decreased in the following order: TSP-10P > canola root ≥ young shoot ≥ TSP-4P > control > mature shoot. Microbial P was greater with residue addition than with TSP and in the control. Residues with low total P and high C: P ratio resulted in P immobilisation in the microbial biomass. Therefore, residues with high total P and low C: P ratio can be an important source of P for plants. Net P immobilisation of mature wheat residues (0.07% P) was significantly reduced by combining wheat residue (C: P ratio 615: 1) with TSP leading to a C: P ratio of 155: 1 to 310: 1. Furthermore, the combination of wheat residue with TSP increased available P in residue and TSP-amended soils by 3.0 mg P kg⁻¹ soil, which was shown to be sufficient to support wheat growth in the early stages of development in the other experiments.
Although water-soluble P fertilizers provide plants with immediately available P, a large proportion becomes unavailable over time. Addition of low C: P residues on the other hand, may not result in high amounts of immediately available P, but the P supply is more sustained due to P release from decomposing residues and turnover of microbial biomass P. Phosphorus immobilization after addition of residues which have high C: P ratio (615: 1) may be offset when residue is applied together with inorganic P fertilizer if the resulting C: P ratio is 300: 1 or less. Overall, this study has highlighted the potential role that crop residues, either alone or in combination with inorganic P, can play in increasing P availability in the light textured, low organic matter, P-limited soils typical of many southern Australian farming systems. The results provide important quantitative information on the potential of a wide range of crop residues to supply wheat with P, and how additions of inorganic P interact with residue decomposition and influence available P supply. This quantitative information will be valuable for the construction or validation of mechanistic models of residue decomposition relevant to low organc matter light textured soils in farming systems of southern Australia, and will ultimately assist in the development of economic management strategies for minimizing P fertilizer inputs and maximizing the benefits of biological cycling of P.Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009
40
Mat, Hassan Hasnuri. "Effects of legume growth and residue decomposition on growth and phosphorus uptake in following wheat." Thesis, 2012. http://hdl.handle.net/2440/77827.
Abstract:
In phosphorus (P) deficient soils, several legumes have been shown to mobilise less labile P pools and to have a greater capacity to take up P than cereals. In conditions where N was not
limiting, some legumes can increase the growth and P uptake of the following cereals which may be related to P mobilisation by the legumes. There is little information about the size of
various soil P pools in the rhizosphere of legumes in soil fertilised with P although P fertiliser is often added to legumes to improve N₂ fixation. The aims of this study were to (i) compare the growth, P uptake and the concentration of rhizosphere soil P pools of different grain legumes, (ii) compare the decomposition rate of grain legume and wheat residues, and (iii) determine the effect of legume pre-crops and residue addition on growth, P uptake and concentrations of rhizosphere P pools of the following wheat. A series of plant growth experiments were carried out in a glasshouse to compare the growth of the different grain legumes and wheat and the concentrations of P pools of the rhizosphere soil. The soil pH determines the dominant P forms, therefore, two soils which were low in available P and contrasting pH (a loamy sand soil pH 8.8 and a sandy loam pH 5.4) were used in separate experiments to which soluble P was added to ensure good plant growth. Additionally, another experiment was conducted in the alkaline soil with lower P supply. Nodulated chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), white lupin (Lupinus albus L.), yellow lupin (Lupinus luteus L.) narrow-leafed lupin (Lupinus
angustifolius L.) and wheat were grown until maturity. Plant dry weight and P uptake were measured, sequential P fractionation was employed to determine the concentrations of P pools in the rhizosphere of the legumes and wheat. Irrespective of soil pH and P supply, growth and P uptake were greatest in faba bean whereas the less labile P pools were most strongly depleted in the rhizosphere of white lupin despite its lower growth and P uptake compared to faba bean. In the alkaline soil with high P supply, compared to the unplanted control soil, the depletion of labile pools (resin P and NaHCO₃) were greater in the rhizosphere of faba bean whereas in the alkaline soil with low P supply and the acidic soil, white lupin depleted most of the labile pools more strongly than the other legumes. An incubation study was carried out to compare the decomposition rate and the available N and P concentrations after addition of the legume and wheat residues. Shoots, roots and the combination of shoots and roots of wheat, faba bean, chickpea and white lupin were mixed into the loamy sand soil. The decomposition rate was measured over 42 days by determining soil CO₂ release and the concentrations of available P and N in the soil were measured on days 0 and 42. Chickpea shoot residue decomposed faster than the other residues. Compared to the control soil without residue addition, resin P concentration was increased with legume residue addition but not with wheat residue addition. Inorganic N was increased significantly with addition of faba bean and white lupin residues compared to the un-amended control whereas wheat residue addition had no effect. In order to differentiate between the effect of the legume pre-crop alone and that of legume pre-crop and their residue on the following wheat, soil grown with legumes from which rootand shoot residues were removed or added back were planted with wheat. Growth, P uptake and concentrations of rhizosphere P pools of the following wheat were measured. Generally, growth was greater in wheat grown in the previously unplanted soil than in the pre-cropped soils. Among the pre-crops, in the alkaline and acidic soils with high P supply, the growth of the following wheat was greater in legume pre-crop soil without residue than with residue addition. The reverse was true for plant P concentration in the alkaline soil whereas in the acidic soil, plant P concentration was similar among the treatments. Varying results with residue addition on the growth of following wheat were observed in the alkaline soil with low P supply, but residue addition consistently increased wheat P concentration. In the loamy sand
(pH 8.8) with high P supply, regardless of the pre-crops, wheat depleted the less labile residual P, NaOH-Pi and particularly NaOH-Po, whereas in the sandy loam (pH 5.4), the depletion was greatest in resin P. Similarly, in the loamy sand soil with low P supply, wheat after legumes depleted labile and less labile pools more than wheat after wheat. Generally, the addition of pre-crop residues increased the size of organic P pools in the rhizosphere of wheat grown in pre-crop soils. The results of this study showed that in the alkaline loamy sand, among the legumes only those with the greatest depletion of either labile or less labile pools (faba bean at high P and white lupin at low P supply) enhanced the growth of the following wheat. At high P supply, the pre-crop faba bean with greatest depletion of labile pools resulted in a greater depletion of less labile pools by the following wheat than the other legumes. At low P supply, the pre-crop white lupin with greatest depletion of labile and less labile pools induced a greater depletion of the less labile pools in the rhizosphere of wheat. On the other hand, in the acidic sandy loam, the legumes with the greatest depletion of most pools (labile and less labile) did not increase the growth of the following wheat compared to legumes with little depletion.
Furthermore, the addition of legume pre-crop residues increased the concentration of organic P pools in the rhizosphere of the following wheat compared to pre-crop alone but generally
decreased wheat growth.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture Food and Wine, 2012
41
Iqbal, Shahriar Mohammod. "Effect of crop residue qualities on decomposition rates, soil phosphorus dynamics and plant phosphorus uptake." 2009. http://hdl.handle.net/2440/49812.
Abstract:
Phosphorus (P) is an essential plant nutrient that may limit plant growth and agricultural productivity if not available for crop plant uptake in sufficient quantities at the time required. Many Australian soils are deficient in available P, despite a long history of P fertilizer application, and this is due to fertilizer P rapidly becoming unavailable largely through biochemical fixation. The resulting low P fertilizer efficiency, coupled with rapidly rising cost of fertilizers, has increased interest in biological cycling of P from sources such as crop residues. However, to date, much of the Australian research has focussed on soils with relatively high organic matter content (> 2%) and relatively heavy texture i.e. medium to high clay content. Furthermore, although there is information on pasture residue decomposition and P release for sandy soils with low organic matter in Australia, a recent shift to continuous cropping systems means that information for a range of crop residues is required but is not currently available. Therefore the aims of the work described in this thesis were to (i) increase the efficiency of P use when crop residue P are applied to crops and (ii) determine the effect of crop residue biochemical quality on decomposition rates, soil P dynamics and plant P uptake in light textured sandy soils with low organic matter which are typical of a large proportion of the southern Australian wheat growing area. A further aim was to investigate the effects of combined additions of plant residue and P fertilizer on P cycling in these soils, a scenario highly relevant to farming systems. A series of soil incubation and plant growth experiments were undertaken to characterize P dynamics in soil following addition of a wide range of crop residues (total 15) collected from agricultural sites throughout South Australia. The residues, differing in age and biochemical quality, were young shoots of canola, lupin, pea, lucerne and lentil; mature shoot residues of canola, lupin, pea and wheat and mature root residues of wheat, canola and lupin. The concentration of total and water soluble P, C, and N in the residues was measured using standard wet chemical analyses and the carbon chemistry was determined by NMR spectroscopy. Decomposition of crop residues was continuously monitored over a period of up to 140 days by measuring soil respiration. Available P and microbial biomass P and C were also assessed at different times during the incubations. The total P in residues ranged from 0.16% to 0.32% and 0.05% to 0.08% in young and mature shoots, respectively. Water-soluble P was related to residue total P and ranged from 29% to 81% and 13% to 29% of total P in young and mature shoots, respectively. The C: P ratio ranged from 133: 1 to 253: 1 and 504: 1 to 858: 1 in young and mature shoots, respectively. Phosphorus availability and microbial P uptake differed between soils amended with crop residues and soluble P fertilizer as triple super phosphate (TSP). Soil respiration rates were significantly higher in soils amended with crop residues than in the soils amended with TSP or the unamended control in the first 58 days of incubation. In an experiment in which residues and TSP were added at a rate of 10 mg P kg⁻¹, available P was greater for TSP than residue-amended soil, whereas microbial P showed the opposite trend. Respiration rate and microbial P were positively correlated with C addition rate, which was highest in mature wheat residue because it had the lowest P concentration. In order to assess when P released from the residues is available for plants, wheat was grown over three consecutive crop periods with each period lasting for 4 weeks. Young residues with high content of water soluble P, C, N and amide and low lignin and phenolic content decomposed faster than mature residues. The C type and amount added with residues controlled the dynamics of P availability. Surprisingly, canola mature root increased available P and plant growth as much as young shoot residues while root residues of wheat and lupin resulted in P immobilization and low plant growth. Compared to canola young shoot, canola mature root has a higher total P concentration and a lower C: P ratio. Plant P uptake was positively correlated with residue total and water-soluble P content and negatively correlated with residue C: P and C: N ratio and amount of C added with the residues. In another experiment where residue was added at 2.5 g C kg⁻¹ soil and compared with TSP (4 and 10 mg P kg⁻¹ soil), available P and plant P uptake decreased in the following order: TSP-10P > canola root ≥ young shoot ≥ TSP-4P > control > mature shoot. Microbial P was greater with residue addition than with TSP and in the control. Residues with low total P and high C: P ratio resulted in P immobilisation in the microbial biomass. Therefore, residues with high total P and low C: P ratio can be an important source of P for plants. Net P immobilisation of mature wheat residues (0.07% P) was significantly reduced by combining wheat residue (C: P ratio 615: 1) with TSP leading to a C: P ratio of 155: 1 to 310: 1. Furthermore, the combination of wheat residue with TSP increased available P in residue and TSP-amended soils by 3.0 mg P kg⁻¹ soil, which was shown to be sufficient to support wheat growth in the early stages of development in the other experiments. Although water-soluble P fertilizers provide plants with immediately available P, a large proportion becomes unavailable over time. Addition of low C: P residues on the other hand, may not result in high amounts of immediately available P, but the P supply is more sustained due to P release from decomposing residues and turnover of microbial biomass P. Phosphorus immobilization after addition of residues which have high C: P ratio (615: 1) may be offset when residue is applied together with inorganic P fertilizer if the resulting C: P ratio is 300: 1 or less. Overall, this study has highlighted the potential role that crop residues, either alone or in combination with inorganic P, can play in increasing P availability in the light textured, low organic matter, P-limited soils typical of many southern Australian farming systems. The results provide important quantitative information on the potential of a wide range of crop residues to supply wheat with P, and how additions of inorganic P interact with residue decomposition and influence available P supply. This quantitative information will be valuable for the construction or validation of mechanistic models of residue decomposition relevant to low organc matter light textured soils in farming systems of southern Australia, and will ultimately assist in the development of economic management strategies for minimizing P fertilizer inputs and maximizing the benefits of biological cycling of P.Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009
42
LIN, XUAN-ZHE, and 林玄哲. "Effects of soil temperature, moisture and uitrogen concentration on the decomposition rate of crop residues in the soil." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/01931005885138779913.
43
MacLeod, Cedric John. "The effects of liquid hog manure application and tillage systems on the rate of cereal crop residue decomposition in clay soils." 2003. http://hdl.handle.net/1993/12326.
44
Bich, NV. "Inter-rotational strategies for sustaining site fertility and productivity of acacia and eucalyptus plantations planted on steep slopes in northern Vietnam." Thesis, 2019. https://eprints.utas.edu.au/31430/1/Bich_whole_thesis.pdf.
Abstract:
In Vietnam, approximately 1.3 M ha of acacia and eucalypt plantations have been established in the past three decades to supply a growing local and international demand for pulp and sawlog. Wood production over successive rotations does not appear sustainable as yields are declining and soils, especially on steep sites, are being eroded and negatively impacted. There is concern that current practices, i.e. burning harvest residues and only applying a small dose of fertilisers at planting are in part responsible for this situation and need to be changed. This thesis examines if changes in the current practices i.e. the retention of harvest residues and increased P fertilisation will improve the soil properties and productivity of Eucalyptus hybrid (Eucalyptus urophylla × E. pellita) and Acacia mangium plantations planted on steep slopes in northern Vietnam.
The first study investigated whether the decomposition of retained A. mangium harvest residues (branches, leaves and bark) could provide sufficient nutrients for the next rotation. The biomass and nutrient content of above-ground stand components of the previous 7-year-old Acacia mangium rotation were examined at harvest, and the rates of decomposition and nutrient release from the harvest residues determined. The decomposition constant k, half-life t0.5 and release of nutrients (N, P, K, Ca and Mg) were monitored by using the litterbag technique for a 1.5-year-period. At harvesting, the total above-ground stand biomass of the previous rotation was 60.8 t ha\(^{-1}\), comprising stemwood (42.7 t ha\(^{-1}\)), bark (8.9 t ha\(^{-1}\)), branches (6.6 t ha\(^{-1}\)) and leaves (2.5 t ha\(^{-1}\)). The retained bark on site made up one-third of the mass of all residues (harvest residues + litter + understorey vegetation) and conserved 6% Mg, 14% K, 18% P, 30% N and 41% Ca content for recycling. The decomposition rate of the leaves was the most rapid (k = 1.47 year\(^{-1}\); t0.5 = 0.47 year), then branches (k = 0.54 year\(^{-1}\); t0.5 = 1.29 year) and bark (k= 0.22 year\(^{-1}\); t0.5 = 3.09 year). During decomposition, the loss of nutrients from harvest residues was K ≈ Ca > N > P> Mg. Over 1.5 years of the study period, as much as 137.1 kg N ha\(^{-1}\), 4.7 kg P ha\(^{-1}\), 20.8 kg K ha\(^{-1}\), 94.5 kg Ca ha\(^{-1}\) and 2.2 kg Mg ha\(^{-1}\) were recycled. The N, Ca and K, though not P and Mg released from decomposing A. mangium harvest residues are potentially able to meet a significant part of the demand by trees growing in the next rotation.
The second study examined whether the retention of residues, and application of phosphorus fertiliser at higher rates than the current practice, can increase rates of growth and vigour of trees, i.e. better tree form and lesser crown damage, of eucalypt and acacia plantations. A factorial combination of residue management (burning vs. retention) and phosphorus (P) fertiliser application at planting (15 vs. 100 kg ha\(^{-1}\)) treatments was applied at a steeply sloping site (slope rages from 8 – 40 ̊). Two adjacent experiments were established, one with A. mangium and the other with E. hybrid. Standing volume (V) and leaf area index (LAI) in A. mangium were greater following burning; this was mostly attributable to the significantly higher survival rate of seedlings. Burning of residues was associated with increases in the number of large branches per tree, and a higher crown damage index (CDI). In the E. hybrid, diameter and height responses to the higher rate of fertiliser were observed at age 6 and 12 months, but not beyond. High P application also led to higher CDI. Standard fertiliser treatment, applied in amounts equivalent to 17, 15 and 8 kg ha\(^{-1}\) of N, P, K, respectively, was adequate to meet the early growth requirement of eucalypt and acacia plantations at this site.
The third study examined the effect of two contrasting harvest residue management treatments (burning vs. residue-retention) on soil properties i.e. soil total carbon (TC), total nitrogen (TN), extractable P (ext-P), exchangeable K (exch-K) and soil bulk density (BD) of E. hybrid and A. mangium plantations. In this study, soil samples were collected in plots treated with similar amounts of fertiliser (applied at the current rate) but subject to contrasting residue management treatments (burning vs. residue-retention). The soil properties were assessed at pre-establishment, and at age one and two years following planting. The results showed that the soil properties in either E. hybrid or A. mangium plantations were not significantly different between residue retention and residue burning inter-rotational treatments. However marked variations observed in soil TC, exch-K and ext-P suggest that position on the slope masked any overall trends.
In summary, the relatively low amounts of harvest residues and high fertility levels at the site may be associated with the lack of significant growth and soil responses to the silvicultural treatments applied in this study. However, it is clear that the decomposition of harvest residues and the associated rate of nutrient release can supply a significant amount of nutrients required for stand development in the next rotation. The variation in standing volume, crown health and soil properties between slope positions suggest that factors driving any correlation of tree productivity with slope, for example surface run-off and soil erosion will need careful management to arrest potential yield decline on steeply sloping sites. Thus harvest residue retention with adequate weed and termite control may be preferential to burning on a steep slope because the residue not only can provide nutrients but reduce water run-off and soil erosion.