Дисертації: "Soil properties and soil organic carbon"

1

Siewert, Matthias. "High-resolution mapping of soil organic carbon storage and soil properties in Siberian periglacial terrain." Licentiate thesis, Stockholms universitet, Institutionen för naturgeografi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-120275.

Повний текст джерела

Анотація:

In the past years considerable attention has been given to soil organic carbon (SOC) stored in permafrost-affected soils in periglacial terrain. Studies have shown that these soils store around half the global SOC pool, making them a key component of the global carbon cycle. Much of the SOC presently stored in these soils has accumulated since the Pleistocene and is protected from decomposition and erosion by low temperatures close to or below the freezing point. This makes it vulnerable to remobilization under a warming climate. This thesis provides new data on SOC storage in three study areas in Siberian periglacial terrain. A high-resolution land cover classification (LCC) for each study area is used to perform detailed vertical and spatial partitioning of SOC. The results show that the vast majority (>86%) of the ecosystem carbon is stored in the top meter of soil. Low relative storage of carbon in plant phytomass indicates limited uptake potential by vegetation and emphasises the vulnerability of the SOC pool to geomorphic changes. Peat formation as well as cryoturbation are identified as the two main pedogenic processes leading to accumulation of SOC. Presence or absence of ice-rich Yedoma deposits determine soil formation and SOC storage at landscape scale. At local scale, periglacial landforms dominate SOC allocation in the tundra, while forest ecosystem dynamics and catenary position control SOC storage in the taiga. A large diversity of soil types is found in these environments and soil properties within pedons can be highly variable with depth. High-resolution satellite imagery allows upscaling of the SOC storage at unprecedented detail, but replication of soil pedons is a limiting factor for mapping of SOC in remote periglacial regions. Future research must look beyond traditional LCC approaches and investigate additional data-sources such as digital elevation models. The concept of state factors of soil formation is advocated as a framework to investigate present day and future SOC allocation in periglacial terrain.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Jung, Ji Young. "Nitrogen Fertilization Impacts on Soil Organic Carbon and Structural Properties under Switchgrass." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1284983372.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Nichols, Lara Kaitlin. "Relationships Among Soil Properties and Soil CO2 Efflux in a Loblolly Pine-Switchgrass Intercropped System." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51945.

Повний текст джерела

Анотація:

The components of soil CO2 efflux are affected by many soil properties including temperature, moisture, microbial abundance and activity, and other soil physical and chemical properties. Changes in these factors can result in high spatial and temporal variability of total soil CO2 efflux. Low molecular weight organic acids (LMWOAs), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), microbial biomass and activity were measured to evaluate the impact of intercropping switchgrass (Panicum virgatum L.) in a loblolly pine (Pinus taeda L.) plantation. Surface soil samples (0-15 cm) were collected on the bed (PSG-B), interbed (PSG-I) and edge (PSG-E) of pine-switchgrass intercropped treatments, as well as pine only (P-B) and switchgrass only (SG-I) treatments. Differences in most soil properties and processes of intercropped treatments were sporadic and most did not show clear trends. However, significant correlations between DOC, soil temperature, oxalic and acetic acids and soil CO2 efflux were present. In an multiple regression model these factors explained 57% of the variance in total soil CO2 efflux. Therefore we think that LMWOAs, as a labile component of DOC, are influencing total CO2 efflux because they are being consumed by microbial community, increasing heterotrophic respiration and as a result overall total CO2 efflux. The amount and distribution of labile C controls microbial community dynamics, heterotrophic respiration as well as the stabilization of soil C.
Master of Science

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Jonsson, Sofia. "The influence of soil and contaminant properties on the efficiency of physical and chemical soil remediation methods." Doctoral thesis, Umeå universitet, Kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-21040.

Повний текст джерела

Анотація:

A vast number of sites that have been contaminated by industrial activities have been identified worldwide. Many such sites now pose serious risks to humans and the environment. Given the large number of contaminated sites there is a great need for efficient, cost-effective remediation methods. Extensive research has therefore been focused on the development of such methods. However, the remediation of old industrial sites is challenging, for several reasons. One major problem is that organic contaminants become increasingly strongly sequestered as they persist in the soil matrix for a long period of time. This process is often referred to as ‘aging’, and leads to decreasing availability of the contaminants, which also affects the remediation efficiency. In the work underlying this thesis, the influence of soil and contaminant properties on the efficiency of various physical and chemical soil remediation methods was investigated. The investigated contaminants were polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). Briefly, the results show that as the size of soil particles decreases the contaminants become more strongly sorbed to the soil’s matrix, probably due to the accompanying increases in specific surface area. This affected the efficiency of the removal of organic pollutants by both a process based on solvent washing and processes based on chemical oxidation. The sorption strength is also affected by the hydrophobicity of the contaminants. However, for a number of the investigated PAHs their chemical reactivity was found to be of greater importance for the degradation efficiency. Further, the organic content of a soil is often regarded as the most important soil parameter for adsorption of hydrophobic compounds. In these studies the effect of this parameter was found to be particularly pronounced for the oxidation of low molecular weight PAHs, but larger PAHs were strongly adsorbed even at low levels of organic matter. However, for these PAHs the degradation efficiency was positively correlated to the amount of degraded organic matter, probably due to the organic matter being oxidized to smaller and less hydrophobic forms. The amount of organic matter in the soil had little effect on the removal efficiency obtained by the solvent-washing process. However, it had strong influence on the performance of a subsequent, granular activated carbon-based post-treatment of the washing liquid. In conclusion, the results in this thesis show that remediation of contaminated soils is a complex process, the efficiency of which will be affected by the soil matrix as well as the properties of the contaminants present at the site. However, by acquiring thorough knowledge of the parameters affecting the treatability of a soil it is possible to select appropriate remediation methods, and optimize them in terms of both remediation efficiency and costs for site- and contaminant-specific applications.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Waiser, Travis Heath. "In situ characterization of soil properties using visible near-infrared diffuse reflectance spectroscopy." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/5915.

Повний текст джерела

Анотація:

Diffuse reflectance spectroscopy (DRS) is a rapid proximal-sensing method that is being used more and more in laboratory settings to measure soil properties. Diffuse reflectance spectroscopy research that has been completed in laboratories shows promising results, but very little has been reported on how DRS will work in a field setting on soils scanned in situ. Seventy-two soil cores were obtained from six fields in Erath and Comanche County, Texas. Each soil core was scanned with a visible near-infrared (VNIR) spectrometer with a spectral range of 350-2500 nm in four different combinations of moisture content and pre-treatment: field-moist in situ, air-dried in situ, field-moist smeared in situ, and air-dried ground. Water potential was measured for the field-moist in situ scans. The VNIR spectra were used to predict total and fine clay content, water potential, organic C, and inorganic C of the soil using partial least squares (PLS) regression. The PLS model was validated with data 30% of the original soil cores that were randomly selected and not used in the calibration model. The root mean squared deviation (RMSD) of the air-dry ground samples were within the in situ RMSD and comparable to literature values for each soil property. The validation data set had a total clay content root mean squared deviation (RMSD) of 61 g kg-1 and 41 g kg-1 for the field-moist and air-dried in situ cores, respectively. The organic C validation data set had a RMSD of 5.8 g kg-1 and 4.6 g kg-1 for the field-moist and air-dried in situ cores, respectively. The RMSD values for inorganic C were 10.1 g kg-1 and 8.3 g kg-1 for the field moist and air-dried in situ scans, respectively. Smearing the samples increased the uncertainty of the predictions for clay content, organic C, and inorganic C. Water potential did not improve model predictions, nor did it correlate with the VNIR spectra; r2-values were below 0.31. These results show that DRS is an acceptable technique to measure selected soil properties in-situ at varying water contents and from different parent materials.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Burgos, Hernandez Tania D. "Assessment of Effects of Long Term Tillage Practices on Soil Properties in Ohio." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429825085.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Woldeselassie, Mical K. "Soil Organic Carbon and Site Characteristics in Aspen and Evaluation of the Potential Effects of Conifer Encroachment on Soil Properties in Northern Utah." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/765.

Повний текст джерела

Анотація:

In the Intermountain West, aspen (Populus tremuloides) has declined mainly due to a combination of successional processes, fire suppression and long-term use of ungulates which has led to replacement by conifers, sagebrush or other shrub communities. Conifer encroachment is believed to cause critical changes in the ecosystem properties. In order to understand the impacts of conifer encroachment on soil properties such as soil organic carbon (SOC) storage, soil morphology, and soil chemical properties, and the implications of such changes, it is very important to assess the soil properties under the two vegetation types. The objectives of this study were to i) quantify SOC stocks and their variability in pure aspen forests; ii) evaluate the role of various biotic and abiotic site parameters as drivers of this SOC; iii) evaluate the effect of conifer encroachment on SOC storage, soil morphology, soil microclimate and soil chemical properties. The study was conducted in three catchments in Northern Utah in two phases: i) a transect study with 33 sampling points in a pure aspen community; ii) a paired plot study based on comparing six plots in to aspen and nearby conifer plots as representatives of end-member communities. Soils under aspen were mainly Mollisols, whereas the soils associated with conifers were classified as Alfisols, Inceptisols and Entisols. Even under pure aspen there was a significant SOC variability among sampling points and aspects, and SOC was negatively correlated with soil moisture index and average tree diameter and positively correlated with vegetation density. The paired plot comparison showed that SOC in the mineral soil (0-60 cm) was significantly higher under aspen, while O horizon thickness and C content was higher under conifers. The total SOC (O layer + mineral soil) was not significantly different among the vegetation types, suggesting an upward redistribution of SOC in conifer soils. The soil moisture in summer was also higher under aspen compared to conifers. Other chemical properties were not affected by vegetation types. Our study indicates that i) no differences in SOC can be detected in surface soil horizons (<20 >cm); ii) SOC is highly variable and greatly influenced by soil moisture and forest characteristics; iii) conifer encroachment is likely to alter soil microclimatic and SOC amount and distribution.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Kuang, Boyan Y. "On-line measurement of some selected soil properties for controlled input crop management systems." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7939.

Повний текст джерела

Анотація:

The evaluation of the soil spatial variability using a fast, robust and cheap tool is one of the key steps towards the implementation of Precision Agriculture (PA) successfully. Soil organic carbon (OC), soil total nitrogen (TN) and soil moisture content (MC) are needed to be monitored for both agriculture and environmental applications. The literature has proven that visible and near infrared (vis-NIR) spectroscopy to be a quick, cheap and robust tool to acquire information about key soil properties simultaneously with relatively high accuracy. The on-line vis-NIR measurement accuracy depends largely on the quality of calibration models. In order to establish robust calibration models for OC, TN and MC valid for few selected European farms, several factors affecting model accuracy have been studied. Nonlinear calibration techniques, e.g. artificial neural network (ANN) combined with partial least squares regression (PLSR) has provided better calibration accuracy than the linear PLSR or principal component regression analysis (PCR) alone. It was also found that effects of sample concentration statistics, including the range or standard derivation and the number of samples used for model calibration are substantial, which should be taking into account carefully. Soil MC, texture and their interaction effects are other principle factors affecting the in situ and on-line vis-NIR measurement accuracy. This study confirmed that MC is the main negative effect, whereas soil clay content plays a positive role. The general calibration models developed for soil OC, TN and MC for farms in European were validated using a previously developed vis-NIR on-line measurement system equipped with a wider vis-NIR spectrophotometer (305 – 2200 nm) than the previous version. The validation results showed this wider range on-line vis-NIR system can acquire larger than 1500 data point per ha with a very good measurement accuracy for TN and OC and excellent accuracy for MC. The validation also showed that spiking few target field samples into the general calibration models is an effective and efficient approach for upgrading the implementation of the on-line vis-NIR sensor for measurement in new fields in the selected European farms.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Selhorst, Adam Louis. "Carbon Sequestration By Home Lawn Turfgrass Development and Maintenance in Diverse Climatic Regions of the United States." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306499049.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Feit, Sharon Jean. "Variability in Hydrology and Ecosystem Properties and Their Role in Regulating Soil Organic Matter Stability in Wetlands of West-Central Florida." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4319.

Повний текст джерела

Анотація:

Soil organic matter (SOM) provides many ecosystem services that are necessary for continued ecosystem function. The accumulation of SOM in an ecosystem is a function of its persistence time which can range from days to thousands of years. Ecosystem properties including dominant vegetation type, soil texture, and soil moisture in various habitats can regulate the persistence time of SOM. Wetlands, because of their associated ecosystem properties, promote SOM accumulation, but little has been done to determine the ecosystem properties that regulate its persistence over time. In west-central Florida, urbanization and increased water demands have suppressed water tables in isolated wetland ecosystems via hydrological connectivity between ground and surficial waters. In this study, variability in wetland ecosystem properties, in particular dominant vegetation type and hydrological parameters, were tested as mechanisms driving SOM accumulation and stability. Cypress wetlands had significantly more organic matter, carbon (C), and nitrogen (N) than herbaceous marshes. In addition, increased wetland inundation promoted stable SOM accumulation in forested wetlands. By increasing the percent time a forested wetland spent aerobic, decreases occurred in both labile and stable C and N pools. As large storage units of SOM, the decreases in both labile and stable C and N pools in wetland soils have large implications for global C and N cycling. Increased manipulation of wetland water levels, especially in short time scales, can mineralize both short-term and long-term storage units of C and N. Globally, the increase mineralization of large SOC and SON stocks would exacerbate the release of air and water quality pollutants. The sensitivity of both labile and stable SOM pools draws concern when anticipating continued water demands and land use changes of the Tampa Bay region.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Lorenz, Klaus. "The role of microorganisms and organic matter quality for nutrient mineralization of carbon composition of organic layers in forests as influenced by site properties and soil management /." Stuttgart : Inst. für Bodenkunde und Standortslehre, 2001. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009736028&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Pilon, Lucas Contarato. "Atributos de um Argissolo Amarelo coeso sob cultivo de cafeeiro a pleno sol e consorciado com espécies arbóreas." Universidade Federal do Espírito Santo, 2013. http://repositorio.ufes.br/handle/10/6564.

Повний текст джерела

Анотація:

Made available in DSpace on 2016-12-23T14:37:30Z (GMT). No. of bitstreams: 1 Lucas Contarato Pilon.pdf: 1648966 bytes, checksum: cac40ef638ed16eaccc0afa53f321565 (MD5) Previous issue date: 2013-02-28
Diante da necessidade de obter informações sobre o cultivo de cafeeiros arborizados, o objetivo do trabalho é avaliar a relação dos atributos químicos, físicos e os componentes da matéria orgânica do solo sob cultivo de café consorciado com diferentes espécies arbóreas, comparativamente ao café cultivado a pleno sol, tendo como referência uma área sob floresta. O trabalho foi conduzido em sistemas de produção de café, numa propriedade familiar, município de Nova Venécia - ES. O solo da área é um ARGISSOLO AMARELO Distrocoeso típico, cultivado com café conilon consorciado com árvores, nos seguintes sistemas de uso e manejo: 1) café sem consórcio (pleno sol), 2) café consorciado com nim (Azadirachta indica), 3) café consorciado com cedro australiano (Cedrela fissilis) e 4) café consorciado com teca (Tectona grandis). Foi utilizado um solo de área florestal, como referência. A amostragem do solo foi realizada nas seguintes profundidades: 0,0 0,05; 0,05 0,10; 0,10 0,20; e 0,20 0,40 m, avaliando-se atributos químicos (pH, P, K, Ca, Mg, Al, H+Al, N, C total, C ext em água, C biomassa microbiana e emissão de CO2) e físicos do solo (granulometria, densidade do solo e de partículas, porosidade total, macro e microporosidade, estabilidade de agregados, resistência do solo à penetração e umidade do solo). A avaliação do carbono solúvel (C ext) e do carbono da biomassa microbiana do solo (CBMS) foi realizada em duas épocas (março e setembro/2012) nas profundidades de 0,0 0,05 e 0,05 0,10 m; já a emissão de CO2 foi medida na mesma época que, na presença e ausência de serapilheira. Os resultados experimentais mostram que os sistemas de uso e manejo apresentam comportamento diferenciado para grande parte dos atributos estudados. O solo florestal apresenta maiores teores e estoques de carbono orgânico total e nitrogênio total, 19,8 e 1,99 Mg ha-1 respectivamente, além de maior teor de carbono na biomassa microbiana (518,8 μg g-1 solo em março e 364,8 μg g-1 solo em setembro). Os atributos dos solos sob cafeeiros consorciados, de maneira geral, não diferem do solo sob cafeeiro a pleno sol, exceção feita para os atributos Mg, N e o C ext, C-BMS, quociente microbiano (qMic) na duas épocas de coleta, os quais são superiores nos consórcios agroflorestais, e o quociente metabólico (qCO2) inferior, denotando maior estabilidade dos cafeeiros arborizados. O café a pleno sol mostra-se um agroecossitema mais perturbado com maior qCO2 (1,81 μg CO2 C-BMS-1 h-1 em março e 2,44 μg CO2 C-BMS-1 h-1 em setembro). A proteção do solo ocasionada pelo sombreamento das árvores e a deposição de serapilheira influencia principalmente os atributos biológicos estudados, favorecendo um maior equilíbrio nos cafeeiros arborizados. Com relação aos atributos físicos, o consórcio proporciona menor densidade do solo, maior porosidade total e macroporosidade do solo, diferindo do café a pleno sol. Os cafeeiros consorciados se diferem somente na agregação do solo. A resistência do solo à penetração é influenciada pela umidade do solo, com destaque para o café a pleno sol que apresenta valores mais baixos desse atributo, em função da irrigação, que eleva a umidade do solo. O estudo numa condição de Argissolo coeso, mostra que 5 anos de implantação de sistemas arborizados são suficiente para apresentar pequenas mudanças nos atributos estudados, no entanto para atributos de alta sensibilidade, como os biológicos, são suficientes para apresentar mudanças mais consistentes dos sistemas de uso e manejo
Faced with the need for information on the coffee agroforestry systems, the objective is to evaluate the relationship of the chemical, physical and components of soil organic matter under coffee intercropping with different tree species, compared to the full-sun coffee with an area under forest like reference. The research was conducted in coffee production systems, a family farm, in Nova Venécia city - ES. The soil is an YELLOW ULTISOL Distrocohesive typical, with shadow coffee plantation, the following different land use systems and management: 1) coffee full (full-sun), 2) coffee intercropped with neem (Azadirachta indica), 3) coffee intercropped with Australian cedar (Cedrela fissilis) and 4) coffee intercropped with Teca (Tectona grandis). It was used a soil of forest area, as a reference. Soil sampling was conducted in the following depths: 0.0-0.05, 0.05-0.10; 0.10-0.20, and 0.20-0.40 m, evaluating chemical soil attributes ( pH, P, K, Ca, Mg, Al, H + Al, total nitrogen (TN), total organic carbon (TOC), water-soluble carbon (WSC), soil microbial biomass carbon (SMBC) and soil CO2 emission and physical soil attributes (particle size, bulk density, total porosity, macroporosity, microporosity and soil resistance penetration), was collected and characterization of accumulated litter. The evaluation of soluble carbon (soluble C) and soil microbial biomass carbon (SMBC) was held twice a year (March and september/2012) at depths from 0.0-0.05 and 0.05-0, 10 m, the soil CO2 emission was measured at the same times, in the presence and absence of litter. The experimental results show that the use and management systems were characterized for most attributes researched. The forest soil has higher levels of stocks and TOC and TN, 19.8 and 1.99 Mg ha-1 respectively, and the higher SMBC (518.8 mg g-1 soil in March and 364, 8 mg g-1 soil in September). The soil under shadow coffee, in general, do not differ from full-sun coffee, except for the attributes Mg, N and soluble C, SMBC, microbial quotient (QMIC) at both harvests, which are higher in agroforestry systems, and attributes TOC/ soluble C and metabolic quotient (qCO2) lower values, indicating greater stability of shadow coffee systems. The full-sun coffee shows more disturbed agroecosystem with high qCO2 (1.81 μg CO2 CBMS-1 h-1in March and 2.44 μg CO2 CBMS-1 h-1 in September). The protection of soil caused by shading from trees and litterfall influences the biological attributes primarily, favoring a greater balance in shadow coffee. Relative to physical attributes, the intercropped provides a lower bulk density, higher total porosity and macroporosity, differing full-sun coffee. The shadow coffee up differs only in soil aggregation. The soil resistance penetration is influenced by soil moisture, especially for full-sun coffee which shows lower values of this attribute, depending on irrigation management, which increase soil moisture. The study provides a ULTISOL cohesive, shows that 5 years of systems implementation, are enough to present small changes in the attributes studied, however high sensitivity to attributes such as biological changes are sufficient to represent most consistent use and management systems

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Bernhard-Bitaud, Corinne. "Modifications de la matière organique et conséquences sur l'adsorption de l'atrazine dans un sol brun de prairie mis en culture." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL128N.

Повний текст джерела

Анотація:

En conditions de plein champ après retournement d'une prairie permanente, on compare pendant cinq ans l'évolution des propriétés d'un sol brun entre deux parcelles, l'une exempte de tout traitement chimique, l'autre désherbée à l'atrazine. On observe au cours du temps une diminution de la stabilité structurale (-30%) et de la teneur en matière organique (- 20%), ainsi qu'une augmentation du rapport isotopique ¹³C/¹²C, du taux d'humification et de l'extractibilité des acides humiques. Toutefois, l'étude des caractéristiques chimiques de la matière organique ne révèle pas de différence majeure entre les deux parcelles tout au long des cinq années. Un fractionnement des agrégats à 50 [micro]m permet de mettre en évidence une plus grande richesse en carbone de la fraction grossière (50-2000 [micro]m) du sol non désherbé par rapport au sol traité, qui peut être attribuée aux importants retours de matière organique fraiche par les adventices. Ces derniers n'affectent cependant pas les caractéristiques qualitatives des matières organiques totales ; ainsi le rapport C/N reste constant et identique dans les deux parcelles. L'analyse en spectroscopie d'absorption infra-rouge des acides humiques et fulviques extraits montre que les groupements fonctionnels des composés humifiés ne sont affectés de façon majeure ni par l'évolution générale du sol ni par le traitement à l'atrazine. Cependant, l'étude de la cinétique d'adsorption de l'atrazine met en évidence une diminution de la vitesse de mise à l'équilibre entre les échantillons les plus anciens et les plus récents. Par ailleurs, la comparaison de l'adsorption entre la fraction fine (0-50 [micro]m) et la fraction grossière (50-200 [micro]m) d'un même échantillon de sol montre que l'adsorption est moins rapide mais également moins réversible sur la fraction grossière. Ces différences de comportement rendent compte de variations très fines de la réactivité des matières organiques, et sont commentées en relation avec la structure hypothétique du complexe argilo-humique

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Zakharova, Anna. "Soil organic matter dynamics: influence of soil disturbance on labile pools." Thesis, University of Canterbury. School of Biological Sciences, 2014. http://hdl.handle.net/10092/9944.

Повний текст джерела

Анотація:

Soils are the largest pool of carbon (C) in terrestrial ecosystems and store 1500 Gt of C in their soil organic matter (SOM). SOM is a dynamic, complex and heterogeneous mixture, which influences soil quality through a wide range of soil properties. Labile SOM comprises a small fraction of total SOM (approximately 5%), but due to its rapid turnover has been suggested to be most vulnerable to loss following soil disturbance. This research was undertaken to examine the consequences of soil disturbance on labile SOM, its availability and protection in soils using the isotopic analysis of soil-respired CO₂ (δ¹³CO₂). A range of soils were incubated in both the short- (minutes) and long-term (months) to assess changes in labile SOM. Shifts in soil-respired δ¹³CO₂ over the course of soil incubations were found to reflect changes in labile substrate utilisation. There was a rapid depletion of δ¹³CO₂ (from a starting range between -22.5 and -23.9‰, to between -25.8 and -27.5‰) immediately after soil sampling. These initial changes in δ¹³CO₂ indicated an increased availability of labile SOM following the disturbance of coring the soil and starting the incubations. Subsequently δ¹³CO₂ reverted back to the initial, relatively enriched starting values, but this took several months and was due to labile SOM pools becoming exhausted. A subsequent study was undertaken to test if soil-respired δ¹³CO₂ values are a direct function of the amount of labile SOM and soil physical conditions. A range of pasture soils were incubated in the short-term (300 minutes), and changes in soil-respired δ¹³CO₂ were measured along with physical and chemical soil properties. Equilibrium soil-respired δ¹³CO₂, observed after the initial rapid depletion and stabilisation, was a function of the amount of labile SOM (measured as hot water extractable C, HWEC), total soil C and soil protection capacity (measured as specific soil surface area, SSA). An independent experimental approach to assess the effect of SSA, where labile SOM was immobilised onto allophane – a clay mineral with large, active surface area – indicated limited availability of labile SOM through more enriched δ¹³CO₂ (in a range between -20.5 and -20.6 ‰) and a significant (up to three times) reduction in HWEC. In the third study, isotopic measurements were coupled with CO₂ evolution rates to directly test whether equilibrium soil-respired δ¹³CO₂ can reflect labile SOM vulnerability to loss. Soils were sampled from an experimental tillage trial with different management treatments (chemical fallow, arable cropping and permanent pasture) with a range of C inputs and soil disturbance regimes. Soils were incubated in the short- (300 minutes) and long-term (600 days) and changes in δ¹³CO₂ and respiration rates measured. Physical and chemical fractionation methods were used to quantify the amount of labile SOM. Pasture soils were characterised by higher labile SOM estimates (HWEC; sand-sized C; labile C respired during long-term incubations) than the other soils. Long-term absence of plant inputs in fallow soils resulted in a significant depletion of labile SOM (close to 50% based on sand-sized C and HWEC estimates) compared with pasture soils. The values of δ¹³CO₂ became more depleted in 13C from fallow to pasture soils (from -26.3 ‰ to -28.1 ‰) and, when standardised (against the isotopic composition of the solid soil material), Δ¹³CO₂ values also showed a decrease from fallow to pasture soils (from -0.3 ‰ to -1.1 ‰). Moreover, these patterns in isotopic measures were in strong agreement with the amount of labile SOM and its availability across the soils, and were best explained by the isotopic values of the labile HWEC fraction. Collectively, these results confirm that labile SOM availability and utilisation change immediately after soil disturbance. Moreover, isotopic analysis of soil-respired CO₂ is a powerful technique, which enables us to probe mechanisms and examine the consequences of soil disturbance on labile SOM by reflecting its availability and the degree of SOM protection.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Suchá, Kateřina. "Hodnocení kvality/zdraví půdy v blízkosti obce Bohaté Málkovice." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392022.

Повний текст джерела

Анотація:

Diploma thesis evaluates quality and healthiness of the soil health located close to Bohate Malkovice focusing on changes in both physical and chemical characteristics of the soil in time. The theoretical part describes physical, chemical, and biological parameters of the soil. Selected physical parameters are structure, texture, determination of measured weight, bulk density of the soil, porosity, actual volumetric water content of the soil, aeration, saturated and unsaturated hydraulic conductivity, infiltration, and colour. Chosen chemical parameters are pH, carbonates, soil electrical conductivity, and humus content. Picked biological parameters are microbial biomass, respiration, nitrogen content, and weed infestation. The practical part analyses selected indicators of quality of the soil from the location of the experiment close to Bohate Malkovice. The area under evaluation has been treated using reduced tillage for long term. The practical part is based on the laboratory examination of disturbed and undisturbed soil samples taken between years 2016 and 2018. Based on outcome results we can evaluate the quality of the soil considering plants growth, development, and soil fertility.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Jang, Wonyong. "Unsteady Multiphase Flow Modeling of In-situ Air Sparging System in a Variably Saturated Subsurface Environment." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7517.

Повний текст джерела

Анотація:

In order to preserve groundwater resources from contamination by volatile organic compounds and to clean up sites contaminated with the compounds, we should understand fate and transport of contaminants in the subsurface systems and physicochemical processes involving remediation technologies. To enhance our understanding, numerical studies were performed on the following topics: (i) multiphase flow and contaminant transport in subsurface environments; (ii) biological transformations of contaminants; (iii) in-situ air sparging (IAS); and, thermal-enhanced venting (TEV). Among VOCs, trichloroethylene (TCE) is one of the most-frequently-detected chemicals in the contaminated groundwater. TCE and its daughter products (cis-1,2-dichloroethylene (cDCE) and vinyl chloride (VC)) are chosen as target contaminants. Density-driven advection of gas phase is generated by the increase in gas density due to vaporization of high-molecular weight contaminants such as TCE in the unsaturated zone. The effect of the density-driven advection on fate and transport of TCE was investigated under several environmental conditions involving infiltration and permeability. Biological transformations of contaminants can generate byproducts, which may become new toxic contaminants in subsurface systems. Sequential biotransformations of TCE, cDCE, and VC are considered herein. Under different reaction rates for two bioreaction kinetics, temporal and spatial concentration profiles of the contaminants were examined to evaluate the effect of biotransformations on multispecies transport. IAS injects clean air into the subsurface below the groundwater table to remediate contaminated groundwater. The movement of gas and the groundwater as a multiphase flow in the saturated zone and the removal of TCE by IAS application were analyzed. Each fluid flow under IAS was examined in terms of saturation levels and fluid velocity profiles in a three-dimensional domain. Several scenarios for IAS systems were simulated to evaluate remedial performance of the systems. TEV was simulated to investigate its efficiency on the removal of a nonaqueous phase liquid in the unsaturated zone under different operational conditions. For numerical studies herein, the governing equations for multiphase flow, multispecies transport, and heat energy in porous media were developed and solved using Galerkin finite element method. A three-dimensional numerical model, called TechFlowMP model, has been developed.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Bader, Nicholas E. "Plant control of soil organic carbon accumulation /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Pereira, Osvaldo José Ribeiro. "Mapping soil organic carbon storage in deep soil horizons of Amazonian Podzols." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-14062016-113621/.

Повний текст джерела

Анотація:

The Podzols of the world are divided into intra-zonal and zonal according to then location. Zonal Podzols are typical for boreal and taiga zone associated to climate conditions. Intra-zonal podzols are not necessarily limited by climate and are typical for mineral poor substrates. The Intra-zonal Podzols of the Brazilian Amazon cover important surfaces of the upper Amazon basin. Their formation is attributed to perched groundwater associated to organic matter and metals accumulations in reducing/acidic environments. Podzols have a great capacity of storing important amounts of soil organic carbon in deep thick spodic horizons (Bh), in soil depths ranging from 1.5 to 5m. Previous research concerning the soil carbon stock in Amazon soils have not taken into account the deep carbon stock (below 1 m soil depth) of Podzols. Given this, the main goal of this research was to quantify and to map the soil organic carbon stock in the region of Rio Negro basin, considering the carbon stored in the first soil meter as well as the carbon stored in deep soil horizons up to 3m. The amount of soil organic carbon stored in soils of Rio Negro basin was evaluated in different map scales, from local surveys, to the scale of the basin. High spatial and spectral resolution remote sensing images were necessary in order to map the soil types of the studied areas and to estimate the soil carbon stock in local and regional scale. Therefore, a multi-sensor analysis was applied with the aim of generating a series of biophysical attributes that can be indirectly related to lateral variation of soil types. The soil organic carbon stock was also estimated for the area of the Brazilian portion of the Rio Negro basin, based on geostatistical analysis (multiple regression kriging), remote sensing images and legacy data. We observed that Podzols store an average carbon stock of 18 kg C m-2 on the first soil meter. Similar amount was observed in adjacent soils (mainly Ferralsols and Acrisols) with an average carbon stock of 15 kg C m-2. However if we take into account a 3 m soil depth, the amount of carbon stored in Podzols is significantly higher with values ranging from 55 kg C m-2 to 82 kg C m-2, which is higher than the one stored in adjacent soils (18 kg C m-2 to 25 kg C m-2). Given this, the amount of carbon stored in deep soil horizons of Podzols should be considered as an important carbon reservoir, face a scenario of global climate change
Os Espodossolos podem ser divididos em zonais e intrazonais de acordo com área onde ocorrem. Os Espodossolos zonais são típicos de áreas boreais e taiga, delimitados por condições climáticas. Já os intrazonais não são condicionados pelo clima. Os Espodossolo intrazonais brasileiros ocupam uma grande extensão da alta bacia amazônica, tendo sua formação atribuída à ocorrência de lençóis freáticos suspensos associados à acumulação de complexos organometálicos em ambientes ácidos redutores. Esses solos tem a capacidade de estocar grandes quantidades de carbono orgânico em horizontes espódicos profundos (Bh), em profundidades que podem variar de 1,5m a 5m. Pesquisas atuais relacionadas ao estoque de carbono em solos amazônicos, não levam em consideração os estoques encontrados no horizonte Bh (abaixo de 1m de profundidade). Sendo assim, o principal objetivo da presente pesquisa foi quantificar e mapear o estoque de carbono nos solos da bacia do Rio Negro, tendo-se em vista aquele estocado no primeiro metro de solo, bem como o carbono armazenado em até 3m de profundidade. A quantidade de carbono orgânico estocado nos solos da bacia do Rio Negro foi estimada em diferentes escalas de mapeamento, desde mapas locais até a escala da bacia do Rio Negro. Imagens de sensoriamento remoto de alta resolução espacial e espectral foram essenciais para viabilizar o mapeamento dos solos nas áreas estudadas e permitir a estimativa do estoque de carbono. Uma análise multisensor foi adotada buscando-se gerar informações biofísicas indiretamente associadas à variação lateral dos tipos de solo. Após o mapeamento do estoque de carbono em escala regional, partiu-se para a estimativa na escala da bacia do Rio Negro, com base em análise geoestatística (krigagem por regressão linear), imagens de sensoriamento remoto e base de dados de domínio público. Após o mapeamento do estoque de carbono na escala da bacia, constatou-se que os Espodossolos têm um estoque médio de 18 kg C m-2, para 1m de profundidade, valor similar ao observado em solos adjacentes (Latossolos e Argissolos) os quais tem um estoque de 15 kg C m-2. Quando são considerados os estoques profundos, até 3m, a quantidade de carbono dos Espodossolos é superior com valores variando de 55 kg C m-2 a 82 kg C m-2. Estoque relativamente maior que aquele observado em solos adjacentes para esta profundidade (18 kg C m-2 a 25 kg C m-2). Portanto, o estoque de carbono profundo dos Espodossolos, não deve ser negligenciado levando-se em conta cenários futuros de mudanças climáticas

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Schnürer, Ylva. "Influence of soil properties and organic pesticides om soil microbial metabolism /." Umeå : Dept. of Forest Ecology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/2006118.pdf.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Nilsson, K. Sofia. "Modelling soil organic matter turnover /." Uppsala : Dept. of Ecology and Environmental Research, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s326.pdf.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Beniston, Joshua W. "Soil Organic Carbon Dynamics and Tallgrass Prairie Land Management." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253558307.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Zatta, Alessandro <1976&gt. "Soil organic carbon dynamics under perennial energy crops." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5921/.

Повний текст джерела

Анотація:

The European renewable energy directive 2009/28/EC (E.C. 2009) provides a legislative framework for reducing GHG emissions by 20%, while achieving a 20% share of energy from renewable sources by 2020. Perennial energy crops could significantly contribute to limit GHG emissions through replacing equivalent fossil fuels and by sequestering a considerable amount of carbon into the soil through the large amounts of belowground biomass produced. The objective of this study is to evaluate the effects of land use change that perennial energy crops have on croplands (switchgrass) and marginal grasslands (miscanthus). For that purpose above and belowground biomass, SOC variation and Net Ecosystem Exchange were evaluated after five years of growth. At aboveground level both crops produced high biomass under cropland conditions as well as under marginal soils. At belowground level they also produced large amounts of biomass, but no significant influences on SOC in the upper layer (0-30 cm) were found. This is probably because of the "priming effect" that caused fast carbon substitution. In switchgrass only it was found a significant SOC increase in deeper layers (30-60 cm), while in the whole soil profile (0-60 cm) SOC increased from 42 to 51 ha-1. However, the short experimental periods (for both switchgrass and miscanthus), in which land use change was evaluated, do not permit to determine the real capacity of perennial energy crops to accumulate SOC. In conclusion the large amounts of belowground biomass enhanced the SOC dynamic through the priming effect resulting in increased SOC in cropland but not in marginal grassland.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Schneiderová, Šárka. "Účinky hospodaření s půdou na kvalitu půdy v blízkosti obce Šardičky." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392105.

Повний текст джерела

Анотація:

This diploma thesis is focused on influence of reduced tillage technology of soil processing on it´s near-surface soil layer (0 to 10 cm). The research was carried out on agricultural land near Šardičky village, where company ZEMO spol. s r.o. provides long-term use of reduced tillage technology. In 2016 the soil quality in this site was evaluated by using physical and hydrophysical parameters, results are presented in the previous bachelor thesis "Selected hydrophysical parameters as indicators of soil quality.". In diploma thesis in addition chemical and other hydrophysical properties have been evaluated to provide a comprehensive assessment of soil quality. In 2016, poppy seed was grown on this site and spring barley was grown in 2017 and 2018. Grab samples and intact soil cores were taken during the vegetation period of the crop. After three years of experimental research, in which I participated, it is possible to assess the development of individual parameters and the influence of reduced tillage technology on near-surface soil layer. The theoretical part of the diploma thesis deals with the description of the reduced tillage technology and problematics of the determination of soil parameters, which are used for evaluation of the quality of the near-surface layer. The practical part deals with evaluation of these parameters according to various authors and describes the development of soil quality during years 2016, 2017 and 2018.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Singh, Mamta Hari Om. "Soil organic carbon pools in turfgrass systems of Ohio." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187117113.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Pengthamkeerati, Patthra. "Soil physical and microbiological properties affected by soil compaction, organic amendments and cropping in a claypan soil /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164537.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Falloon, Peter Daniel. "Large scale spatial modelling of soil organic carbon dynamics." Thesis, University of Nottingham, 2001. http://eprints.nottingham.ac.uk/12338/.

Повний текст джерела

Анотація:

Under the Kyoto Protocol, participating nations are required to reduce National CO₂emissions according to their 'reduction commitment' or 'quantified emissions limitation', over the first commitment period, 2008-2012. One way in which nations could achieve this would be by increasing soil carbon storage through different management practices. Most former estimates of regional scale C sequestration potential have made use of either linear regressions based on long-term experimental data, whilst some have used dynamic soil organic matter (SOM) models linked to spatial databases. Few studies have compared these two methods, and none have compared regressions with two different SOM models. This thesis presents a case study investigation of the potential of different land management practices to sequester carbon in soil in arable land, and preliminary estimates of other potential C savings. Two dynamic SOM models were chosen for this study, RothC (a soil process model) and CENTURY (a general ecosystem model). RothC and CENTURY are the two most widely used and validated SOM models world-wide. Methods were developed to enhance use and comparability of the models in a predictive mode. These methods included a) estimation of the IOM pool for RothC, b) estimation of C inputs to soil, c) investigation of pool size distributions in CENTURY, and d) creation of a program to allow use of C inputs derived from CENTURY with the RothC model. This thesis has also investigated the importance of errors in C inputs to soil for predictive SOM modelling, and performed sensitivity analyses to investigate how errors in setting the size refractory SOM pools might affect predictions of SOC. RothC and CENTURY were compared at the site scale using datasets from seven European long-term experiments, in order to a) verify their ability to predict SOC changes under changes in land use and management relevant to studies of C sequestration potential, b) evaluate model performance under European climatic conditions, and c) compare the performance of the two models. Finally, a Geographic Information System (GIS) containing soil, land use and climate layers, was assembled for a case study region in Central Hungary. GIS interfaces were developed for the RothC and CENTURY models, thus linking them to spatial datasets at the regional level. This allowed a comparison of estimates of the C sequestration potential of different land management practices obtained using the two models and using regression-based estimates. Although estimates obtained by the different approaches were of the same order of magnitude, differences were observed. Encouragingly, some of the land management scenarios studied here showed sufficient C mitigation potential to meet Hungarian CO₂reduction commitments.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Ma, Li. "Soil Organic Nitrogen - Investigation of Soil Amino Acids and Proteinaceous Compounds." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51960.

Повний текст джерела

Анотація:

Soil carbon (C) and nitrogen (N) are predominantly in organic form. Proteins/ peptides, as an important organic form of N, constitute a substantial part of soil organic matter. On one hand, proteins/peptides are an important N source for plants and microorganisms, particularly in soils where inorganic N is limited. On the other hand, their stabilization in soils by forming organo-mineral associates or macromolecule complex reduces the C loss as CO2 into the atmosphere. Therefore, studies on the turnover, abundance, composition, and stability of proteins/peptides are of crucial importance to agricultural productivity and environmental sustainability. In the first part of this study, the bioavailability and distribution of amino acids, (building block of proteins/peptides), were investigated, in soils across the North-South and West-East transects of continental United States. The second part of this study aimed to understand the variations of organic C speciation in soils of continental United States. Previous investigations of the interactions between soil minerals and proteins/peptides were mostly limited to batch sorption experiments in labs, seldom of which gave the details at the molecular scales. Therefore, in the third part of this study, the molecular orientation of self-assembled oligopeptides on mineral surfaces was investigated by employing synchrotron based polarization-dependent Near Edge X-ray Adsorption Fine Structure Spectroscopy (NEXAFS) techniques. Specific aims of this study were: 1) to assess potentially bioavailable pool of proteinaceous compounds and the immediately bioavailable pool of free amino acids in surface and subsurface soils of various ecosystems; 2) to evaluate the relationship between environmental factors and levels/composition of the two pools; 3) to investigate the organic C speciation in soils of various land use; and 4) to understand molecular level surface organization of small peptides on mineral surfaces. The levels of free amino acids and hydrolysable amino acids which represent the potentially bioavailable pool of proteinaceous compounds in A-horizon soils were significantly high than in C-horizon soils due to the accumulation of organic matter in surface. On average, free amino acids accounted for less than 4 % of hydrolysable amino acids which represent the total proteinaceous compounds in soils. The composition of free amino acids was significantly different between surface soil and subsurface soil and was significantly influenced by mean annual temperature and precipitation. A relatively uniform composition of hydrolysable amino acids was observed irrespective of a wide range of land use. Significant variations were observed for the levels of free and hydrolysable amino acids along mean annual temperature and precipitation gradients, as well as among vegetation types of continental USA, suggesting levels of free and hydrolysable amino acids were associated with the above-ground biomass and root distribution. Organic C speciation investigation revealed the presence of carboxylic-C (38%), aliphatic-C (~ 22%), aromatic-C (~ 18%), O/N-alkyl-C (~ 16%), and phenolic-C (< 6%). Factors such as temperature and vegetation cover were revealed in this study to account for the fluctuations of the proportions of aromatic-C and phenolic-C, in particular. Phenolic-C may serve as a good indicator for the effect of temperature or vegetation on the composition of SOC. The average composition of soil organic C, over the continental scale, was relatively uniform over various soil ecosystems and between two soil horizons irrespective of surface organic C content. Polarization dependent NEXAFS analysis showed the oligopeptides tend to orient on mineral surface with an average tilt angle of 40 ° between the molecular chain and the mineral surface.
Ph. D.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Gottschalk, Pia. "Modelling soil organic carbon dynamics under land use and climate change." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=186643.

Повний текст джерела

Анотація:

Soil organic matter (SOM) models simplify the complex turnover dynamics of organic matter in soils. Stabilization mechanisms are currently thought to play a dominant role in SOM turnover but they are not explicitly accounted for in most SOM models. One study addresses the implementation of an approach to account for the stabilization mechanism of physical protection in the SOC model RothC using 13C abundance measurements in conjunction with soil size fractionation data. SOM models are increasingly used to support policy decisions on carbon (C) mitigation and credibility of model predictions move into the focus of research. A site scale, Monte Carlo based model uncertainty analysis of a SOM model was carried out. One of the major results was that uncertainty and factor importance depend on the combination of external drivers. A different approach was used with the SOM ECOSSE model to estimate uncertainties in soil organic carbon (SOC) stock changes of mineral and organic soils in Scotland. The average statistical model error from site scale evaluation was transferred to regional scale uncertainty to give an indication of the uncertainty in national scale predictions. National scale simulations were carried out subsequently to quantify SOC stock changes differentiating between organic and mineral soils and land use change types. Organic soils turned out to be most vulnerable to SOC losses in the last decades. The final study of this thesis emplyed the RothC model to simulate possible futures of global SOC stock changes under land use change and ten different climate scenarios. Land use change turned out to be of minor importance. The regionally balance between soil C inputs and decomposition leads to a diverse map of regional C gains and losses with different degrees of certainty.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Chen, Yujuan. "The Influence of Urban Soil Rehabilitation on Soil Carbon Dynamics, Greenhouse Gas Emission, and Stormwater Mitigation." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51240.

Повний текст джерела

Анотація:

Global urbanization has resulted in rapidly increased urban land. Soils are the foundation that supports plant growth and human activities in urban areas. Furthermore, urban soils have potential to provide a carbon sink to mitigate greenhouse gas emission and climate change. However, typical urban land development practices including vegetation clearing, topsoil removal, stockpiling, compaction, grading and building result in degraded soils. In this work, we evaluated an urban soil rehabilitation technique that includes compost incorporation to a 60-cm depth via deep tillage followed by more typical topsoil replacement. Our objectives were to assess the change in soil physical characteristics, soil carbon sequestration, greenhouse gas emissions, and stormwater mitigation after both typical urban land development practices and post-development rehabilitation. We found typical urban land development practices altered soil properties dramatically including increasing bulk density, decreasing aggregation and decreasing soil permeability. In the surface soils, construction activities broke macroaggregates into smaller fractions leading to carbon loss, even in the most stable mineral-bound carbon pool. We evaluated the effects of the soil rehabilitation technique under study, profile rebuilding, on soils exposed to these typical land development practices. Profile rebuilding incorporates compost amendment and deep tillage to address subsoil compaction. In the subsurface soils, profile rebuilding increased carbon storage in available and aggregate-protected carbon pools and microbial biomass which could partially offset soil carbon loss resulting from land development. Yet, urban soil rehabilitation increased greenhouse gas emissions while typical land development resulted in similar greenhouse gas emissions compared to undisturbed soils. Additionally, rehabilitated soils had higher saturated soil hydraulic conductivity in subsurface soils compared to other practices which could help mitigate stormwater runoff in urban areas. In our study, we found urban soil management practices can have a significant impact on urban ecosystem service provision. However, broader study integrating urban soil management practices with other ecosystem elements, such as vegetation, will help further develop effective strategies for sustainable cities.
Ph. D.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Sparke, Shaun P. "The influence of selected organic amendments on soil physiochemical properties : effects on soil erosion." Thesis, Liverpool John Moores University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546743.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Veronesi, Fabio. "3D advance mapping of soil properties." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7848.

Повний текст джерела

Анотація:

Soil is extremely important for providing food, biomass and raw materials, water and nutrient storage; supporting biodiversity and providing foundations for man-made structures. However, its health is threatened by human activities, which can greatly affect the potential of soils to fulfil their functions and, consequently, result in environmental, economic and social damage. These issues require the characterisation of the impact and spatial extent of the problems. This can be achieved through the creation of detailed and comprehensive soil maps that describe both the spatial and vertical variability of key soil properties. Detailed three-dimensional (3D) digital soil maps can be readily used and embedded into environmental models. Three-dimensional soil mapping is not a new concept. However, only with the recent development of more powerful computers has it become feasible to undertake such data processing. Common techniques to estimate soil properties in the three-dimensional space include geostatistical interpolation, or a combination of depth functions and geostatistics. However, these two methods are both partially flawed. Geostatistical interpolation and kriging in particular, estimate soil properties in unsampled locations using a weighted average of the nearby observations. In order to produce the best possible estimate, this form of interpolation minimises the variance of each weighted average, thus decreasing the standard deviation of the estimates, compared to the soil observations. This appears as a smoothing effect on the data and, as a consequence, kriging interpolation is not reliable when the dataset is not sampled with a sampling designs optimised for geostatistics. Depth function approaches, as they are generally applied in literature, implement a spline regression of the soil profile data that aims to better describe the changes of the soil properties with depth. Subsequently, the spline is resampled at determined depths and, for each of these depths, a bi-dimensional (2D) geostatistical interpolation is performed. Consequently, the 3D soil model is a combination of a series of bi-dimensional slices. This approach can effectively decrease or eliminate any smoothing issues, but the way in which the model is created, by combining several 2D horizontal slices, can potentially lead to erroneous estimations. The fact that the geostatistical interpolation is performed in 2D implies that an unsampled location is estimated only by considering values at the same depth, thus excluding the vertical variability from the mapping, and potentially undermining the accuracy of the method. For these reasons, the literature review identified a clear need for developing, a new method for accurately estimating soil properties in 3D – the target of this research, The method studied in this thesis explores the concept of soil specific depth functions, which are simple mathematical equations, chosen for their ability to describe the general profile pattern of a soil dataset. This way, fitting the depth function to a particular sample becomes a diagnostic tool. If the pattern shown in a particular soil profile is dissimilar to the average pattern described by the depth function, it means that in that region there are localised changes in the soil profiles, and these can be identified from the goodness of fit of the function. This way, areas where soil properties have a homogeneous profile pattern can be easily identified and the depth function can be changed accordingly. The application of this new mapping technique is based on the geostatistical interpolation of the depth function coefficients across the study area. Subsequently, the equation is solved for each interpolated location to create a 3D lattice of soil properties estimations. For this way of mapping, this new methodology was denoted as top-down mapping method. The methodology was assessed through three case studies, where the top-down mapping method was developed, tested, and validated. Three datasets of diverse soil properties and at different spatial extents were selected. The results were validated primarily using cross-validation and, when possible, by comparing the estimates with independently sampled datasets (independent validation). In addition, the results were compared with estimates obtained using established literature methods, such as 3D kriging interpolation and the spline approach, in order to define some basic rule of application. The results indicate that the top-down mapping method can be used in circumstances where the soil profiles present a pattern that can be described by a function with maximum three coefficients. If this condition is met, as it was with key soil properties during the research, the top-down mapping method can be used for obtaining reliable estimates at different spatial extents.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Wong, Vanessa, and u2514228@anu edu au. "The effects of salinity and sodicity on soil organic carbon stocks and fluxes." The Australian National University. Faculty of Science, 2007. http://thesis.anu.edu.au./public/adt-ANU20080428.223144.

Повний текст джерела

Анотація:

Soil is the worlds largest terrestrial carbon (C) sink, and is estimated to contain approximately 1600 Pg of carbon to a depth of one metre. The distribution of soil organic C (SOC) largely follows gradients similar to biomass accumulation, increasing with increasing precipitation and decreasing temperature. As a result, SOC levels are a function of inputs, dominated by plant litter contributions and rhizodeposition, and losses such as leaching, erosion and heterotrophic respiration. Therefore, changes in biomass inputs, or organic matter accumulation, will most likely also alter these levels in soils. Although the soil microbial biomass (SMB) only comprises 1-5% of soil organic matter (SOM), it is critical in organic matter decomposition and can provide an early indicator of SOM dynamics as a whole due to its faster turnover time, and hence, can be used to determine soil C dynamics under changing environmental conditions.¶ Approximately 932 million ha of land worldwide are degraded due to salinity and sodicity, usually coinciding with land available for agriculture, with salinity affecting 23% of arable land while saline-sodic soils affect a further 10%. Soils affected by salinity, that is, those soils high in soluble salts, are characterised by rising watertables and waterlogging of lower-lying areas in the landscape. Sodic soils are high in exchangeable sodium, and slake and disperse upon wetting to form massive hardsetting structures. Upon drying, sodic soils suffer from poor soil-water relations largely related to decreased permeability, low infiltration capacity and the formation of surface crusts. In these degraded areas, SOC levels are likely to be affected by declining vegetation health and hence, decreasing biomass inputs and concomitant lower levels of organic matter accumulation. Moreover, potential SOC losses can also be affected from dispersed aggregates due to sodicity and solubilisation of SOM due to salinity. However, few studies are available that unambiguously demonstrate the effect of increasing salinity and sodicity on C dynamics. This thesis describes a range of laboratory and field investigations on the effects of salinity and sodicity on SOC dynamics.¶ In this research, the effects of a range of salinity and sodicity levels on C dynamics were determined by subjecting a vegetated soil from Bevendale, New South Wales (NSW) to one of six treatments. A low, mid or high salinity solution (EC 0.5, 10 or 30 dS/m) combined with a low or high sodicity solution (SAR 1 or 30) in a factorial design was leached through a non-degraded soil in a controlled environment. Soil respiration and the SMB were measured over a 12-week experimental period. The greatest increases in SMB occurred in treatments of high-salinity high-sodicity, and high-salinity low-sodicity. This was attributed to solubilisation of SOM which provided additional substrate for decomposition for the microbial population. Thus, as salinity and sodicity increase in the field, soil C is likely to be rapidly lost as a result of increased mineralisation.¶ Gypsum is the most commonly-used ameliorant in the rehabilitation of sodic and saline-sodic soils affected by adverse soil environmental conditions. When soils were sampled from two sodic profiles in salt-scalded areas at Bevendale and Young, SMB levels and soil respiration rates measured in the laboratory were found to be low in the sodic soil compared to normal non-degraded soils. When the sodic soils were treated with gypsum, there was no change in the SMB and respiration rates. The low levels of SMB and respiration rates were due to low SOC levels as a result of little or no C input into the soils of these highly degraded landscapes, as the high salinity and high sodicity levels have resulted in vegetation death. However, following the addition of organic material to the scalded soils, in the form of coarsely-ground kangaroo grass, SMB levels and respiration rates increased to levels greater than those found in the non-degraded soil. The addition of gypsum (with organic material) gave no additional increases in the SMB.¶ The level of SOC stocks in salt-scalded, vegetated and revegetated profiles was also determined, so that the amount of SOC lost due to salinisation and sodication, and the increase in SOC following revegetation relative to the amount of SOC in a vegetated profile could be ascertained. Results showed up to three times less SOC in salt-scalded profiles compared to vegetated profiles under native pasture, while revegetation of formerly scalded areas with introduced pasture displayed SOC levels comparable to those under native pasture to a depth of 30 cm. However, SOC stocks can be underestimated in saline and sodic landscapes by setting the lower boundary at 30 cm due to the presence of waterlogging, which commonly occurs at a depth greater than 30 cm in saline and sodic landscapes as a result of the presence of high or perched watertables. These results indicate that successful revegetation of scalded areas has the potential to accumulate SOC stocks similar to those found prior to degradation.¶ The experimental results from this project indicate that in salt-affected landscapes, initial increases in salinity and sodicity result in rapid C mineralisation. Biomass inputs also decrease due to declining vegetation health, followed by further losses as a result of leaching and erosion. The remaining native SOM is then mineralised, until very low SOC stocks remain. However, the C sequestration potential in these degraded areas is high, particularly if rehabilitation efforts are successful in reducing salinity and sodicity. Soil ecosystem functions can then be restored if organic material is available as C stock and for decomposition in the form of either added organic material or inputs from vegetation when these salt-affected landscapes are revegetated.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Sequeira, Cleiton Henrique. "Soil Organic Matter Dynamics in Cropping Systems of Virginia's Valley Region." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/37381.

Повний текст джерела

Анотація:

Soil organic matter (SOM) is a well known indicator of soil quality due to its direct influence on soil properties such as structure, soil stability, water availability, cation exchange capacity, nutrient cycling, and pH buffering and amelioration. Study sites were selected in the Valley region of Virginia with the study objectives to: i) compare the efficiency of density solutions used in recovering free-light fraction (FLF) organic matter; ii) compare different soil organic fractions as sensitive indices of short-term changes in SOM due to management practices; iii) investigate on-farm effects of tillage management on soil organic carbon (SOC) and soil organic nitrogen (SON) stocks; and iv) evaluate the role of SOM in controlling soil available nitrogen (N) for corn uptake. The efficiency of the density solutions sodium iodide (NaI) and sodium polytungstate (SPT) in recovering FLF was the same at densities of 1.6 and 1.8 g cm⁻³, with both chemicals presenting less variability at 1.8 g cm⁻³. The sensitivity of SOM fractions in response to crop and soil management depended on the variable tested with particulate organic matter (POM) being the most sensitive when only tillage was tested, and FLF being the most sensitive when crop rotation and cover crop management were added. The on-farm investigation of tillage management on stocks of SOC and total soil N (TSN) indicated significant increases at 0–15 cm depth by increasing the duration (0 to 10 years) of no-tillage (NT) management (0.59 ± 0.14 Mg C ha⁻¹ yr⁻¹ and 0.05 ± 0.02 Mg N ha⁻¹ yr⁻¹). However, duration of NT had no significant effect on SOC and TSN stocks at 0–60 cm depth. Soil available N as controlled by SOM was modeled using corn (Zea mays L.) plant uptake as response and several soil N fractions as explanatory variables. The final model developed for 0–30 cm depth had 6 regressors representing the different SOM pools (active, intermediate, and stable) and a 𝑅² value of 65%. In summary, this study provides information about on-farm management affects on SOM levels; measurement of such effects in the short-term; and estimation of soil available N as related to different soil organic fractions.
Ph. D.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Lucas, Shawn Thomas. "Evaluation of labile soil carbon test for prediction of soil productivity response to organic matter management." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2175.

Повний текст джерела

Анотація:

Thesis (M.S.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Dept. of Natural Resource Sciences and Landscape Architecture. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Chacón, Montes de Oca Paula. "Effect of Land Use, Climate and Soil Structure on Soil Organic Carbon in Costa Rican Ecoregions." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1252995403.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Liang, Baochang. "Soil organic carbon and soil nitrogen fractions in a Quebec soil as influenced by corn plant population, hybrid, irrigation and fertilization." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55697.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Deiss, Leonardo. "Soil Organic Phosphorus and carbon on agricultural and natural ecosystems." reponame:Repositório Institucional da UFPR, 2016. http://hdl.handle.net/1884/46044.

Повний текст джерела

Анотація:

Orientador : Dr. Anibal de Moraes, Dr Jeferson Dieckow e Dr. Alan J. Franzluebbers
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Agronomia. Defesa: Curitiba, 24/10/2016
Inclui referências: f. 47-50;72-77;97-101
Área de concentração: Produção vegetal
Resumo: A disponibilidade de solos e seus recursos está reduzindo com a evolução da humanidade e os impactos negativos, decorrentes do mau uso dos solos, estão afetando o desenvolvimento sustentável da agropecuária mundial. Portanto, se faz necessário o desenvolvimento de alternativas que permitam um uso mais sustentável dos solos, para atender as demandas no setor de produção agropecuária do século 21. O objetivo geral desta tese foi estudar solos de sistemas de produção agropecuária que buscam a intensificação de uso sustentável, ou de ecossistemas naturais, como uma etapa para melhor entender dinâmicas complexas de nutrientes. Foram estudados a composição de fósforo (P) no solo em sistemas integrados de produção agropecuária (SIPA) no subtrópico brasileiro, bem como em ecossistemas naturais em escala global e por fim, a dinâmica do carbono (C) orgânico em um sistema agroflorestal localizado na Carolina do Norte, Estados Unidos da América. O primeiro objetivo específico foi determinar a composição de P no solo de agroecossitemas com baixa e alta complexidade trófica. Especificamente, objetivou-se qualificar e quantificar os componentes orgânicos e inorgânicos de P usando extratos de NaOH-EDTA e espectroscopia de ressonância magnética nuclear, para posteriormente caracterizar a ciclagem de P em resposta ao aumento da complexidade trófica com SIPA no subtrópico brasileiro. A presença do pastejo resultou em maior concentração de ortofosfato total e biodisponível (i.e., Mehlich-I) e também diminuiu a concentração de P orgânico, incluindo os inositol fosfatos. O pastejo aumentou a biodisponibilidade de P e reduziu a concentração de P orgânico recalcitrante (i.e., inositol fosfatos), portanto, concluiu-se que a integração entre lavoura e pecuária pode ser uma alternativa sustentável para aumentar o uso do P nos sistemas de produção no subtrópico brasileiro. O segundo objetivo específico foi analisar com meta-regressão (meta-análise), a dinâmica do P em diferentes texturas de solo e de clima em escala global, relacionando os grupos funcionais de P com o pH, concentração de C, relação CN e relação CP do solo em ecossistemas naturais. A composição de P orgânico teve uma resposta complexa à estas características do solo. A relação de monoesteres para o P orgânico aumentou com o aumento do pH, e diminuiu com o decréscimo da concentração de C, relação CN e relação CP, sem haver resposta particular para os locais e textura do solo. Em contraste, a relação de diesteres para o P orgânico bem como a relação diesteres para monoesteres teve o comportamento inverso, diminuindo com o aumento do pH, e aumentando com o aumento da concentração de C, relação carbono-nitrogênio (CN) e relação carbono-fósforo (CP). Portanto, concluiu-se que o pH, a concentração de C e as relações CN e CP são importantes fatores na determinação das proporções dos grupos funcionais de P orgânico do solo. O terceiro objetivo específico foi determinar a distribuição espacial de atributos do solo (textura e frações de C orgânico do solo) usando a combinação de espectroscopia de reflectância no infravermelho proximal (NIRS) e geoestatística, em um experimento de sistema agroflorestal localizado na Carolina do Norte, Estados Unidos da América. O NIRS foi uma ferramenta útil para predizer a textura do solo e as frações de C do solo. Na fase de calibração e validação do NIRS, o modelo de máquina de vetores de suporte teve uma performance melhor do que o modelo de mínimos quadrados parciais na predição das características do solo. A geoestatística aumentou os erros em relação àquales obtidos somente com o NIRS. Entretanto, a geoestatística possibilitou realizar a exploração das características espaciais da textura do solo e frações de C. A combinação do NIRS com a geoestatística pode ser utilizada para avaliação de atributos do solo deste sistema agroflorestal e de outros sistemas de produção, permitindo assim aumentar a sustentabilidade dos agroecossistemas através do manejo com agricultura de precisão. Palavras chave: integração lavoura-pecuária, plantio direto, ciclagem de nutrientes.
Abstract: Soil resources are narrowing as human evolution occurs and the negative feedbacks resulting from soil misuse are affecting agriculture's sustainable development worldwide. Therefore, alternatives that allow a more sustainable use of soils are necessary, to fill demands of the 21-century agriculture. The general objective of this thesis was to evaluate soils of agricultural systems that pursue sustainable intensification and natural ecosystems as a step to understand complex nutrient dynamics, which knowledge might help to adapt management by agriculture. It was studied the soil phosphorus compounds on integrated crop-livestock systems in Subtropical Brazil and on natural ecosystems across the world and soil organic carbon (C) dynamics in an agroforestry system on a Coastal Plain in United States of America. The first specific objective was to determine soil P composition from agro-ecosystems with low and high trophic complexity. Specifically, we wanted to qualify and quantify soil organic and inorganic P fractions using NaOH-EDTA extraction and nuclear magnetic resonance spectroscopy, and characterize P cycling in response to increasing complexity with integrated crop-livestock systems in subtropical Brazil. Our results were that in these agro-ecosystems, grazing compared with nograzing had greater soil P content as total and bioavailable (i.e., Mehlich-I) orthophosphate and lower soil organic P and fewer monoesters, including inositol phosphates. Grazing increased P bioavailability and reduced recalcitrant organic P (i.e., inositol phosphates) concentration in soil; therefore, we conclude that integrating crop and livestock systems can be a sustainable alternative to improve P use in farming systems of subtropical Brazil. The second specific objective was to analyze through meta-regression, soil organic phosphorus dynamics among different soil textures and locates at global scale, relating its organic functional groups with soil pH, C concentration, carbon-to-nitrogen (CN) ratio and carbon-to-phosphorus (CP) ratio on natural ecosystems. We found that soil organic P composition had a complex response to those soil characteristics. Monoesters-to-organic P ratio increased as pH increased, and decreased as C concentration, CN ratio and CP ratio increased, with no particular response among locates and soil textures. In contrast, diesters-to-organic P ratio as well as diesters-to-monoesters ratio had the opposite behavior, decreasing its concentrations as pH increased, and increasing as soil C concentration, CN ratio and CP ratio increased. Therefore we concluded that soil pH, C concentration, CN ratio and CP ratio are important factors in determining proportions of soil organic P functional groups. The third specific objective was to determine the spatial distribution soil properties (soil texture and organic C fractions) using a combination of near infrared spectroscopy and geostatistics, in an emerging agroforestry system experiment on a Coastal Plain site in North Carolina. Nearinfrared spectroscopy was a useful tool to predict soil texture and soil organic carbon (SOC) fractions. Using chemometrics to calibrate NIRS, a support vector machine model performed better than a partial least squares model to predict soil texture (sand and clay) and SOC fractions (total, particulate, and mineralizable C determined as the flush of CO2-C following rewetting of dried soil). Geostatistics increased errors of soil properties compared to those obtained solely by NIRS prediction. Nonetheless, geostatistics was useful to explore spatial patterns of soil texture and SOC fractions. Combining NIRS and geostatistics can be promoted for soil evaluation of this agroforestry system and in other landscapes to increase sustainability of agroecosystems through field-specific precision management. Key words: mixed crop-livestock, no-tillage, nutrient cycling.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Bowen, Susan. "Biologically relevant characteristics of dissolved organic carbon (DOC) from soil." Thesis, University of Stirling, 2006. http://hdl.handle.net/1893/115.

Повний текст джерела

Анотація:

Of the organic matter in soils typically < 1% by weight is dissolved in the soil solution (dissolved organic matter; DOM). DOM is a continuum of molecules of various sizes and chemical structures which has largely been operationally defined as the fraction of total organic carbon in an aqueous solution that passes through a 0.45 µm filter. Although only representing a relatively small proportion, it represents the most mobile part of soil organic carbon and is probably enriched with highly labile compounds. DOM acts as a source of nutrients for both soil and aquatic micro-organisms, influences the fate and transport of organic and inorganic contaminants, presents a potential water treatment problem and may indicate the mobilisation rate of key terrestrial carbon stores. The objective of this research was to ascertain some of the biologically relevant characteristics of soil DOM and specifically to determine: (1) the influence of method and time of extraction of DOM from the soil on its biochemical composition and concentration; (2) the dynamics of DOM biodegradation; and, (3) the effects of repeated applications of trace amounts of DOM on the rate of soil carbon mineralization. To examine the influence of method and time of extraction on the composition and concentration of DOM, soil solution was collected from a raised peat bog in Central Scotland using water extraction, field suction lysimetry, and centrifugation techniques on a bimonthly basis over the period of a year (Aug 2003 – Jun 2004). Samples were analysed for dissolved organic carbon (DOC), dissolved organic nitrogen (DON), protein, carbohydrate and amino acid content. For all of the sampled months except June the biochemical composition of DOC varied with extraction method, suggesting the biological, chemical and/or physical influences on DOC production and loss are different within the differently sized soil pores. Water-extractable DOC generally contained the greatest proportion of carbohydrate, protein and/or amino acid of the three extraction methods. Time of extraction had a significant effect on the composition of water- and suction-extracted DOC: the total % carbohydrate + protein + amino acid C was significantly higher in Oct than Dec, Feb and Jun for water-extracted DOC and significantly greater in Dec than Aug, Apr and Jun for suction-extracted DOC. There was no significant change in the total % carbohydrate + protein + amino acid C of centrifuge-extracted DOC during the sampled year. Time of extraction also had a significant effect on the % protein + amino acid N in water- and centrifuge-extracted DON: Oct levels were significantly higher than Feb for water-extracted DON and significantly higher in Aug and Apr for centrifuge-extracted DON. Concentrations of total DOC and total DON were also found to be dependent on time of extraction. DOC concentrations showed a similar pattern of variation over the year for all methods of extraction, with concentrations relatively constant for most of the year, rising in April to reach a peak in Jun. DON concentrations in water- and centrifuge-extracted DON peaked later, in Aug. There were no significant seasonal changes in the concentration of suction-extracted DON. A lack of correlation between DOC and DON concentrations suggested that DOC and DON production and/or loss are under different controls. Laboratory-based incubation experiments were carried out to examine the dynamics of DOC biodegradation. Over a 70 day incubation period at 20oC, the DOM from two types of peat (raised and blanket) and four samples of a mineral soil (calcaric gleysol), each previously exposed to a different management strategy, were found to be comprised of a rapidly degradable pools (half-life: 3 – 8 days) and a more stable pool (half-life: 0.4 to 6 years). For all soil types/treatments, excepting raised peat, the total net loss of DOC from the culture medium was greater than could be accounted for by the process of mineralization alone. A comparison between net loss of DOC and loss of DOC to CO2 and microbial biomass determined by direct microscopy suggested that at least some of the differences between DOC mineralised and net DOC loss were due to microbial assimilation and release. Changes in the microbial biomass during the decomposition process showed proliferation followed by decline over 15 days. The protein and carbohydrate fractions showed a complex pattern of both degradation and production throughout the incubation. The effects of repeated applications of trace amounts of litter-derived DOC on the rate of carbon mineralization over a 35 day period were investigated in a laboratory based incubation experiment. The addition of trace amounts of litter-derived DOC every 7 and 10.5 days appeared to ‘trigger’ microbial activity causing an increase in CO2 mineralisation such that extra C mineralised exceeded DOC additions by more than 2 fold. Acceleration in the rate of extra C mineralised 7 days after the second addition suggested that either the microbial production of enzymes responsible for biodegradation and/or an increase in microbial biomass, are only initiated once a critical concentration of a specific substrate or substrates has been achieved. The addition of ‘DOC + nutrients’ every 3.5 days had no effect on the total rate of mineralization. To date DOC has tended to be operationally defined according to its chemical and physical properties. An understanding of the composition, production and loss of DOC from a biological perspective is essential if we are to be able to predict the effects of environmental change on the rate of mineralization of soil organic matter. This research has shown that the pools of DOC extracted, using three different methods commonly used in current research, are biochemically distinct and respond differently to the seasons. This suggests some degree of compartmentalisation of biological processes within the soil matrix. The observed similarities between the characteristics of the decomposition dynamics of both peatland and agricultural DOC suggests that either there is little difference in substrate quality between the two systems or that the microbial community have adapted in each case to maximise their utilisation of the available substrate. The dependency of the concentration and biochemical composition of DOC on the seasons requires further work to ascertain which biotic and/or abiotic factors are exerting control. Published research has focussed on factors such as temperature, wet/dry cycles, and freeze/thawing. The effect of the frequency of doses of trace amounts of DOC on increasing the rate of soil organic C mineralization, evident from this research, suggests that the interval between periods of rainfall may be relevant. It also emphasises how it can be useful to use knowledge of a biological process as the starting point in determining which factors may be exerting control on DOC production and loss.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Uddin, Jashim. "Soil organic carbon dynamics in two major alluviums of Bangladesh." Thesis, Kingston University, 2016. http://eprints.kingston.ac.uk/35756/.

Повний текст джерела

Анотація:

This study was designed to evaluate the status, distribution, spatial variability, controlling factors, storage, and change in the levels of soil organic carbon (SOC) in two major alluviums of Bangladesh. The two alluviums the Brahmaputra and the Ganges were selected because they occupy a large area of Bangladesh with a wide diversity of agro-ecosystems. SOC levels were studied across the four sub-sites in the aforementioned alluviums at 0-30 cm depths to evaluate their spatial and temporal variability. The sub-sites, Delduar and Melandah, are in the Brahmaputra alluvium. The other two sub-sites, Mirpur and Fultala, are in the Ganges alluvium. Additionally, SOC and total nitrogen (TN) distribution were studied across eight soil profiles (0-120 cm depths) under the two alluviums. The results revealed that the SOC contents were very low in all the sites. The classical statistics showed that the variability of the SOC was moderate across the four sub-sites. The SOC distribution was positively skewed across all the sub-sites except Fultala. A semivariogram model showed there was generally a weak spatial correlation (R2 < 0.5) of SOC in the study sites. A relatively large sampling grid (1600m) and intensive soil management were perhaps responsible for the observed weak spatial dependency. SOC variability is lower across the highland (HL) and medium highland (MHL) sites than the medium lowland (MLL) and lowland (LL) sites. Changes in land use and land cover were also more intensive in the HL and MHL sites than the MLL and LL sites. The reason for low SOC in the HL and MHL sites may be due to their lower inundation level, e.g., land levels in relation to flooding depths, together with greater intensity of use. Temporal variability of SOC datasets revealed that SOC has declined across all the sites during the last 20-25 years due to the intensive land use with little or no crop residue inputs. It is plausible that SOC has declined to an equilibrium level, and further decline may not occur unless land use intensity changes further. The findings show that SOC is positively related to the TN and clay contents in the soils. This is not surprising as SOC is a major pool of TN, and soil clay fraction is known to protect SOC degradation. SOC and TN storage is higher in the surface soil horizon (0-20 cm) than the sub surface soils. Topsoil horizon is tilled and receives greater crop residue inputs which are subsequently mineralized resulting in higher accumulation of SOC and TN. It appears that inundation land types and land management practices may be the major driving factors of SOC storage and distribution across the study sites.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Blumenthal, Kinsey Megan. "Predicting Spatial Variability of Soil Organic Carbon in Delmarva Bays." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73692.

Повний текст джерела

Анотація:

Agricultural productivity, ecosystem health, and wetland restoration rely on soil organic carbon (SOC) as vital for microbial activity and plant health. This study assessed: (1) accuracy of topographic-based non-linear models for predicting SOC; and (2) the effect of analytic strategies and soil condition on performance of spectral-based models for predicting SOC. SOC data came from 28 agriculturally converted Delmarva Bays sampled down to 1 meter. R2 was used as an indicator of model performance. For topographic-based modeling, correlation coefficients and condition indices reduced 50 terrain-related values to three datasets of 16, 11, and 7 variables. Five types of non-linear models were examined: Generalized Linear Mondel (GLM) ridge, GLM LASSO, Generalized Additive Model (GAM) non-penalized, GAM cubic splice, and partial least-squares regression. Carbon stocks varied widely, 50 to 219 Mg/ha, with the average around 93 Mg/ha. Topography shared a weak relationship to SOC with most attributes showing a correlation coefficient less than 0.3. GLM ridge and both GAMs achieved moderate accuracy at least once, usually using the 16 or 11 variable datasets. GAMs consistently performed the best. Prior to carbon analysis, hyperspectral signatures were recorded for the topmost soil horizons under different conditions: moist unground, dry unground, and dry ground. Twenty-four math treatment and smoothing technique combinations were run on each hyperspectral dataset. R2 varied greatly within datasets depending on analytic strategy, but all datasets returned an R2 greater than 0.9 at least twice. Moist unground soil models outperformed the others when comparing the best models among datasets.
Master of Science

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Gmach, Maria Regina. "Sugarcane straw removal from the soil surface: effects on soil soluble products." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-18012019-174951/.

Повний текст джерела

Анотація:

The interest in using sugarcane straw as a feedstock for bioenergy production has been increased considerably. However, indiscriminate straw removal may negatively affect soil functioning. Therefore, this work aimed to quantify and characterize soil solution translocating along the profile, under straw removal rates from the soil surface. Lysimeter systems were built with 1, 20, 50, and 100 cm soil columns, with a sandy clay loam texture, from a commercial sugarcane field in Piracicaba-SP, southeastern Brazil. The experiment was conducted in open area, where the lysimeters were subjected to rainfall and sun radiation. After the soil stabilization within the lysimeters, the treatments were added, consisting of four straw amounts (0, 3, 6, and 12 Mg ha-1), representing straw removal rates of 100 (bare soil), 75, 50, and 0%, respectively. After one year of the first straw addition, the same straw amounts were added again simulating the second harvest. Drained solution was collected and quantified by 17 months and soil moisture was determined over a period of two months using sensors. Dissolved organic carbon (DOC) concentration was measured in automatic analyzer. The soil solution and straw solution, made in water infusion, were characterized in High performance liquid chromatography (HPLC) to verify the presence of toxic compounds. After that, straw and soil solution were used in tests with soybean seed to evaluate the effects in plant germination and initial growth. At the end of the experiment, soil bulk density and soil organic carbon (SOC) analyses were performed. Remaining straw was weight before the new addition, and weight again at the end to determine the decomposition rates. The accumulated volume of solution drained was 30, 11 and 4% lower under 100, 75 and 50% removal rates compared to no removal. Bare soil stored less water, indicating susceptibility to lose water by evaporation. Simulation showed that 100% and 75% removal can induce longer periods of water restriction, which impair sugarcane growth. The DOC production on topsoil was higher in no straw removal; the retention was higher in 1 to 20 cm in no removal and higher in 20 to 50 cm in 50 and 75% removal rates. Bare soil released more DOC below 01 cm indicating a possible C loss. Below 100 cm DOC leachate was quite similar in all treatments, what shows a higher C retention and small C loss even in higher DOC production. Even with differences in DOC retention, increases in C stock below 5 cm were not noticed. We found many phenolic compounds in the straw solution, not found in the soil solution, indicating that in natural conditions straw does not release toxic compounds into soil solution. Plant growth was negatively affected by straw solution, but not by soil solution. Our findings suggest that the medium straw maintenance prevents variations and loss on soil water content. Higher straw amount increases DOC production, which likely alters its composition and subsequent retention in soil. Carbon stock did not increase in the soil subsurface, but probably will in the long-term. The higher straw removal, proportionally, the higher the C losses in the form of CO2 and DOC, consequently the lower soil C retention. More straw on soil surface release more C amounts to the soil, retained or translocated with soil water, may be stored in deeper soil layers. Higher water percolation in the soil profile does not mean higher C losses by leaching in deeper soil. This study has the practical objective of finding an amount of straw to be maintained in the field that ensures the C storage and the better soil functioning, and also supply feedstock for bioenergy production.
O interesse no uso da palha de cana-de-açúcar como matéria-prima para a produção de bioenergia vem crescendo consideravelmente. No entanto, a remoção excessiva da palha pode afetar negativamente o funcionamento do solo. Portanto, o objetivo deste trabalho foi quantificar e caracterizar a solução ao longo do perfil sob níveis de remoção de palha da superfície do solo. Para isso, foi construído um sistema de lisímetros com colunas de 1, 20, 50 e 100 cm de solo, de textura franco argilo arenosa, proveniente de área comercial de cana-de-açúcar em Piracicaba-SP, Brasil. O experimento foi conduzido em área aberta, sujeito a precipitação e luz natural. Depois da estabilização do solo dentro dos tubos, foram adicionados os seguintes tratamentos: 0, 3, 6 e 12 Mg ha-1 de massa seca, representando 100 (solo nu), 75, 50 e 0% de intensidade de remoção de palha, respectivamente, sendo adicionados novamente após um ano. A solução percolada foi coletada e quantificada por 17 meses, a umidade do solo foi determinada por dois meses usando sensores. A concentração de carbono orgânico dissolvido (COD) foi mensurada com analisador automático. A solução do solo e solução da palha, feita por infusão em água, foram caracterizadas em HPLC para verificar a presença de compostos tóxicos. Posteriormente, as soluções da palha e solo foram usadas em testes de sementes de soja para avaliar os efeitos na germinação e crescimento inicial. Ao final do experimento, foram realizadas análises de densidade do solo e carbono orgânica do solo (COS). A palha remanescente foi pesada após um ano, anterior a nova adição, e pesada novamente ao final do experimento, para determinar a taxa de decomposição. O volume de solução percolado foi 30, 11 e 4% menor em 100, 75 e 50% do que em 0% de remoção, respectivamente. O solo descoberto armazenou menos água, indicando susceptibilidade à perda de água por evaporação. A simulação mostrou que 100 e 75% de remoção induzem longos períodos de restrição hídrica, que pode prejudicar o crescimento da planta. A produção de COD na camada superficial foi maior no solo sem remoção; a retenção foi maior de 1 a 20 cm em solo sem remoção, e maior em 20 a 50 cm em 50 e 75% de remoção. O solo descoberto liberou mais COD em de 20 cm do que em superfície, indicando perda de C. Abaixo de 100 cm, o COD lixiviado foi similar nos tratamentos, indicando grande retenção de C e pequenas perdas por lixiviação, mesmo em alta produção de COD. Mesmo com diferenças na retenção de COD, não foi identificado aumento no estoque de C abaixo de 5 cm. Foram encontrados compostos fenólicos na solução da palha, não encontrados na solução do solo, indicando que em condições naturais a palha não libera quantidades significativas de compostos tóxicos na solução do solo. O crescimento de plantas foi negativamente afetado pela solução da palha, mas não pela solução do solo. Nossos resultados sugerem que a manutenção de quantidade média de palha previne perdas e variação no conteúdo de água do solo. Maior quantidade de palha aumenta a produção de COD, que provavelmente altera sua composição, alterando a retenção no solo. O estoque de C não aumentou consideravelmente em subsuperfície, mas muito provavelmente aumentará em escala de tempo maior. Quanto maior a remoção de palha, proporcionalmente maior as taxas de C liberadas na forma de CO2 e COD em subsuperfície, consequentemente, menor a retenção de C no solo. Maiores quantidades de palha na superfície liberam mais C para o solo, retido ou translocado com a água, podendo ser estocado em maiores profundidades do solo. Maior percolação de água no solo não significa maiores perdas de C por lixiviação em profundidade.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Mishra, Umakant. "PREDICTING STORAGE AND DYNAMICS OF SOIL ORGANIC CARBON AT A REGIONAL SCALE." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243890700.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Arvidsson, Emeli. "Invasive Earthworms and their effect on Soil Organic Matter : Impact on Soil Carbon ‘Quality’ in Fennoscandian Tundra." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184402.

Повний текст джерела

Анотація:

Arctic soils contain a large fraction of our planets terrestrial carbon (C) pool. When tundra soils become warmer and permafrost thaws, non-native geoengineering earthworms can enter these soils and ingest organic matter accumulated over long timescales. Previous studies have found that earthworms increase mineralization rates of soil organic matter into carbon dioxide (CO2) when introduced. Yet, this initial mineralization boost seems transient with time and it has been hypothesized that earthworms stimulate the formation of persistent C forms. In this study, I investigated how non-native, geoengineering earthworms affected the relative proportions of seven carbon forms in the O and A1 horizon of tundra soil and if their effect induced a change in pH. I used Nuclear Magnetic Resonance (NMR) spectroscopy to understand what happens to soil carbon compounds in two different tundra vegetation types (heath and meadow), that had been subjected to earthworm treatment for three summers. I found that O-aromatic C increased from 7.22% ± 0.24 (mean ± stderr) in the meadow soil lacking earthworms to 8.98% ± 0.30 in the meadow exposed to earthworms, and that aromatic C increased from 8.71% ± 0.23 to 9.93% ± 0.25. In similar, the result suggested that alkyl C decreased in this vegetation type from 20.43% ± 0.38 to 18.70% ± 0.25 due to earthworm activities. I found no effect on the chemical properties in the heath. I conclude that geoengineering earthworms affect the two vegetation types differently and that earthworms seem to enhance the accumulation of recalcitrant aromatic C forms.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Doohan, Thomas James. "Drivers of Soil Organic Matter Stabilization across Ohio." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1597941993038872.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Linder, Katie Jo. "The Effect of Soil Cation Balancing on Soil Properties and Weed Communities in an Organic Rotation." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449103848.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Dou, Fugen. "Long-term tillage, cropping sequence, and nitrogen fertilization effects on soil carbon and nitrogen dynamics." Texas A&M University, 2006. http://hdl.handle.net/1969.1/3831.

Повний текст джерела

Анотація:

Management practices that may increase soil organic matter (SOM) storage include conservation tillage, especially no till (NT), enhanced cropping intensity, and fertilization. My objectives were to evaluate management effects on labile [soil microbial biomass (SMB) and mineralizable, particulate organic matter (POM), and hydrolyzable SOM] and slow (mineral-associated and resistant organic) C and N pools and turnover in continuous sorghum [Sorghum bicolor (L.) Moench.], wheat (Triticum aestivum L.), and soybean [Glycine max (L.) Merr.], sorghum-wheat/soybean, and wheat/soybean sequences under convent ional tillage (CT) and NT with and without N fertilization. A Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochepts) in southern central Texas was sampled at three depth increments to a 30-cm depth after wheat, sorghum, and soybean harvesting. Soil organic C and total N showed similar responses to tillage, cropping sequence, and N fertilization following wheat, sorghum, and soybean. Most effects were observed in surface soils. NT significantly increased SOC. Nitrogen fertilization significantly increased SOC only under NT. Compared to NT or N addition, enhanced cropping intensity only slightly increased SOC. Estimates of C sequestration rates under NT indicated that SOC would reach a new equilibrium after 20 yr or less of imposition of this treatment. Labile pools were all significantly greater with NT than CT at 0 to 5 cm and decreased with depth. SMB, mineralizable C and N, POM, and hydrolyzable C were highly correlated with each other and SOC, but their slopes were significantly different, being lowest in mineralizable C and highest in hydrolyzable C. These results indicated that different methods determined various fractions of total SOC. Results from soil physical fractionation and 13C concentrations further supported these observations. Carbon turnover rates increased in the sequence: ROC < silt- and clayassociated C < microaggregate-C < POM-C. Long-term incubation showed that 4 to 5% of SOC was in active pools with mean residence time (MRT) of about 50 days, 50% of SOC was in slow pools with an average MRT of 12 years, and the remainder was in resistant pools with an assumed MRT of over 500 years.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Kroll, Jeffrey T. "LANDUSE AND SOIL ORGANIC CARBON VARIABILITY IN THE OLD WOMAN CREEK WATERSHED OF NORTH CENTRAL OHIO." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1165431813.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Wordell-Dietrich, Patrick [Verfasser]. "Stability of soil organic carbon in the subsoil / Patrick Wordell-Dietrich." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2021. http://d-nb.info/1227577613/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Ghee, Claire. "Mechanistic controls on the mineralisation and stabilisation of soil organic carbon." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227956.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Olaya, Adriana Marcela Silva. "Soil organic carbon dynamics in sugarcane crop in south-central Brazil." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-12082014-144101/.

Повний текст джерела

Анотація:

Sugarcane cropping is an important component of the Brazil´s economy. As the main feedstock used to produce ethanol, the area occupied with this crop has meaningfully increased in the last years and continues to expand in order to attend to the national and international demand of this biofuel. Despite that it has been demonstrated that land-use transition into sugarcane can negatively impact the soil carbon (C) dynamics, little is known about the effect of those land use changes (LUC) processes on the distribution of soil organic carbon (SOC) within particle-size classes, and how management practices in sugarcane can contribute to the C restoration. In this sense the main objective of this study was to evaluate through a modelling application the SOC dynamics in the sugarcane crop in response to LUC and different management scenarios. For a better understanding of LUC impact on C content in both particulate organic matter and mineral-associated fraction, we performed physical soil C fractionation in 34 study areas involving the three major land-use systems affected by sugarcane expansion. Also, biometric measurements were executed in sugarcane plant and ratoon crop in order to use those data in the model parameterization as well as to recalculate the payback time of the C debt through C conversion ratio reported in the literature. Finally, we parameterized and validate the CENTURY ecosystem model for sugarcane, pastures and annual cropland by using a data-set previously collected by the Laboratório de Biogeoquímica Ambiental (CENA-USP); then different scenarios of sugarcane management were simulated: i) SC1 - Green harvesting; ii) SC2 - Green harvesting plus organic amendments and iii) Green harvesting + low N inputs. Our results showed that the C content depletion for conversion from native vegetation and pastures to sugarcane is caused by C losses in the labile fraction (37%) as wells as in the stabilized pool associated to the mineral fraction (30%). Above and belowground biomass quantification indicated a total sugarcane carbon inputs ranging from 29.6 Mg C ha-1 to 30.6 Mg C ha-1. Considering a C retention rate of 13% we estimated net carbon changes of 0.58 to 0.6 Mg C ha-1 year-1, which contribute to reduce the payback times for sugarcane biofuel carbon debts in 3.3 and 1.2 years for Cerrado wooded and pasture conversions into sugarcane respectively. The modelling study supported the Century model as a tool to access the SOC dynamics following land-use conversion and different soil management in in sugarcane. Long-term simulations suggested that changes in the sugarcane harvest from burning to green harvesting increase the soil C stock in an average of 0.21 Mg ha-1 year-1; however the potential of C accumulation is still higher when organic amendments as vinasse and filter cake are add to the soil, with mean values varying between 0.34 and 0.37 Mg ha-1 year-1 in SC2 and SC1 respectively. By analyzing the SOC dynamic at each scenario simulated, we estimated a time span of 17 and 24 years for soil C restoration in clay and sandy soils under pastures with priority suitability (SC3). The number of years was projected to be higher in clay soils with regular suitability (40 years).
A cultura da cana-de-açúcar é uma comodity importante para a economia no Brasil. Como a principal matéria prima para a produção de etanol, a área plantada com esta cultura tem incrementado significativamente nos últimos anos e a tendência é de continuar se expandindo para atender a demanda nacional e internacional deste biocombustível. Embora tenha sido demostrado que a mudança de uso da terra (MUT) para cana-de-açúcar pode afetar negativamente a dinâmica do carbono (C) no solo, há pouca informação disponível acerca do impacto dessa MUT na distribuição do C nas frações da matéria orgânica do solo, e como as praticas de manejo da cana-de-açúcar podem contribuir para o acumulo de C no solo. Nesse contexto o principal objetivo desta pesquisa foi avaliar, através da modelagem matemática, a dinâmica do carbono orgânico do solo (COS) na cultura da cana-de-açúcar em resposta a mudança de uso da terra e diferentes cenários de manejo agrícola. Fracionamento físico para separar o C associado à matéria orgânica partícula (POM) do C ligado à fração mineral do solo (<53 um) foi realizado em amostras de solo de 34 áreas de estudo envolvendo os três principais sistemas de uso da terra afetados pela expansão da cana-de-açúcar. Adicionalmente, foram realizadas avaliações biométricas da cana-de-açúcar (cana planta e soca) que objetivaram a parametrização do modelo matemático assim como recalcular o tempo de reposição do debito de C gerado. Finalmente, o modelo CENTURY foi parametrizado e devidamente validado, para posteriormente proceder à simulação de diferentes cenários futuros de manejo da cana de açúcar: i) SC1 - Colheita de cana crua (sem queima); ii) SC2 - Colheita de cana crua e adição de adubos orgânicos (vinhaça e torta de filtro); iii) Colheita de cana crua e redução da adubação nitrogenada. Os resultados indicaram que a redução do conteúdo de C devido à conversão de vegetação nativa e pastagem para cana-de-açúcar foi causada pela perda de C tanto na fração lábil (37%) quanto na fração mais estável associada a fração mineral do solo (30%). A quantificação da biomassa aérea e radicular indicou entradas de C variando de 29,6 Mg C ha-1 a 30,6 Mg C ha-1, os quais resultariam em uma taxa de acumulo liquido de 0,58 a 0,6 Mg C ha-1 ano-1, que quando considerado contribui a redução do \"payback time\" do debito de C do etanol causado pela conversão de Cerrado e pastagem em 3,3 e 2 anos respectivamente. Os resultados obtidos no estudo de modelagem matemática suportaram o uso do modelo CENTURY como uma ferramenta para avaliar a influencia da MUT e das práticas de manejo na dinâmica do COS. As simulações em longo prazo sugeriram que a supressão da queima na colheita incrementa o estoque de C em 0,21 Mg ha-1 ano-1. No entanto o potencial de acúmulo de C é ainda maior quando adubação orgânica é realizada, com valores entre 0,34 e 0,37 Mg ha-1 ano-1 respectivamente. A análise da dinâmica do COS em cada cenário de manejo simulado permitiu estimar o tempo médio de recuperação do C do solo perdido pela MUT em áreas de pastagens. Os resultados indicaram um período de 17 anos para condições de cultivo sob solos argilosos e 24 anos para solos arenosos (SC3) em áreas de alta aptidão para expansão. O modelo projetou um maior número de anos em solo argiloso sob áreas de pastagem com aptidão média (40 anos).

Стилі APA, Harvard, Vancouver, ISO та ін.

Дисертації з теми "Soil properties and soil organic carbon"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями