Rozprawy doktorskie na temat „Soil microbial biomass”

This thesis describes research investigating the side-effects of pesticides on soil microbial biomass and microbial activity, with particular reference to two recently developed pesticides, a fungicide, epoxiconazole, and a herbicide, quinmerac. In a dose-responsee xperiment,a pplication of thesep esticidest o a sandy loam soil, at up to 10 and 20 times field rate, had no significant effect on soil microbial biomass C or ninhydrin-reactive N, over 84 days incubation. There was also no effect on soil respiration, except for the higher rate quinmerac-treated soil, which evolved 13% lessC02-Cthan the control. The rate of mineralisation of epoxiconazole and quinmerac, and their long-term effect on soil respiration, were measured in three contrasting soils: a sandy loam, a silty clay loam, and a clay soil, using 14C -labelled active ingredients. The kinetics of the pesticides' mineralisation were quite different, epoxiconazole being hyperbolic, while quinmerac was sigmoidal. The maximum amount of mineralisation of both pesticides occurred in the silty clay loam soil, which had the lowest microbial biomass content. The mineralisation of the pesticides was increased by the addition of ryegrass, with the greatest effect in the silty clay loam soil, probably because of the large ryegrass C: biomass C ratio. The mineralisation of epoxiconazole was affected by the ryegrass amendment much more than quinmerac. Further additions of the pesticides had no significant effect on soil respiration or pesticide mineralisation. The mineralisation of epoxiconazole and quimnerac was further investigated in the silty clay loam soil, using samples with different crop management histories, and the effects of ryegrass and glucose amendment. Pesticide mineralisation was shown to be related to the amount of soil microbial biomass, indicating that the difference in mineralisation rate between the three soil types above was not due to differences in their crop management, but innate differences in soil chemistry and microbiology. Ryegrass addition stimulated the mineralisation of epoxiconazole more than quinmerac, while the reverse was true for glucose, indicating that the pesticides were being degraded by two distinct fractions of the microbial biomass. The effects of long-term cumulative field application of the pesticides benomyl, chlorfenvinphos, aldicarb, triadimefon and glyphosate, on soil microbial biomass and mineralisation of soil organic matter were investigated. The addition of aldicarb consistently increased the microbial biomass, due to its beneficial effect on crop growth, but this effect was not reflected in the rate of organic matter mineralisation. However, in general, the continued application of these pesticides for up to 19 years, at slightly higher than the recommended rates, had very little effect on the soil microbial population. The effects of epoxiconazole and triadimefon on soil ergosterol content and microbial biomass C were compared in a sandy loam soil. Both pesticides temporarily reduced soil ergosterol by about 30%, while biomass C remained largely unaffected. However, when straw was added to the soils, the inhibition of ergosterol was still evident, as was an inhibitory effect on biomass C. The measurement of soil ergosterol was more sensitive to the pesticide effects than biomass C, and could be a useful test in determining changes in fungal populations.

This study investigated the effect of water potential on soil microbial C and N pools. Two soil types were treated with additions of salt solution to establish osmotic water potentials, and by ceramic plate - pressure chamber apparatus to establish matric water potentials. Soils were then subjected to short-term incubations. Soil microbial C and N contents (BC and BN) were measured mainly by the fumigation-extraction and fumigation-incubation methods. Results showed that both Microbial C and N pools were markedly affected by soil water potential. The soil microbial C content always showed an increase with increasing water stress and then a decrease beyond a threshold value of water stress, compared to the microbial C content at a control water potential of -0.03 MPa (-0.3 Bar). This response pattern to water stress was true, not only for osmotic stress, but also for matric stress, and regardless of the osmotic agent employed. The response pattern of the microbial N pool to water stress generally contrasted with that of the C pool, and depended on the osmotic strength of the extraction solution (K₂SO₄) used in the determination. Non-isotonic extraction after fumigation resulted in a decrease in microbial N content with increasing water stress, while isotonic extraction resulted in an increase with increasing water stress, beyond a threshold value of water stress. Soil microbial C/N ratio always increased with increasing water stress. Matric water stress had a more marked effect on BC and BN than osmotic stress. The possible reasons for the response patterns of BC, BN and microbial C/N ratio have been discussed in this thesis. Some suggestions on the methodology of microbial biomass measurement for water stressed soil samples have been made, and mainly relate to the biomass fumigation techniques and possible changes in the Kc, Kce and Kn values under water stress, and to the substrate induced respiration (SIR) method and suppressed respiration under water stress.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The land use in Caatinga has caused changes in their properties, as well as behavior and quality of organic matter. extractive character changes, agro pastoral and agricultural biome has taken this to an unsustainable condition, with profound changes in the dynamics and the stock C and its fractions, linked to changes in the microbial community that plays an important role in nutrient cycling in the soil. The objective of this study was to evaluate changes in soil C, its labile and recalcitrant but the activity and microbial diversity in soils under different vegetation covers and historical uses. seven areas were studied which consisted of native forest (F) without human action, forest with predominance of mimosa (AF) and the other with ipe (IP); three areas converted into farmland irrigated elephant grass (EG), irrigated corn (MI) and corn without irrigation (M); and a farmyard area (NF). They were collected in different areas samples at depths of 0-5, 5-10 and 10-20 cm, respectively. Evaluated the total stocks of C and N, water-soluble carbon (CSA) and the C cumulative mineralized after 32 days of incubation, the carbon oxidizable fractions (F1, F2, F3 and F4) and its fractions humic soil (C-FAH C-FAF and C-HUM), C microbial biomass, microbial quotient (qMIC) and structure the microbial community by phospholipid fatty acid analysis (PFLA). The conversion of the savanna for maize cultivation causes a decrease of 56 and 38% in stocks of C and N in the soil. The larger C stocks were observed in AF coverage, while for N, M stood out with lower stocks of this element and also below at all depths to the CSA. The C mineralizable showed linear behavior, observing a reduction in average C mineralized accumulated up to 21.03% in the intermediate depth. The AF, F and IP coverage had higher carbon content in oxidizable fractions for all depths evaluated. The AF area showed higher C levels in labile forms. The C of humic fractions showed inventories in C-FAF fractions and C-FAH 3.59 and 3.73 t ha-1, respectively for AF area; and 22.64 t ha-1 in C-HUM fraction for EG. The area with MI showed greater efficiency in the use of C for microorganisms at different depths. For CBM, coverage with F had a higher concentration, down to 78.32% in depth. Further total Pflas EG concentrations were observed in the area with a larger population of bacteria and fungi in relation to the predominance of gram positive bacteria over gram negative. F1 fractions, CSA and CHUN contributed most significantly to the increase in the stock of C and N soil. Areas converted agícola production, has the potential to change the fractions of COS and microbial activity, especially when it is making use of irrigation in these environments. The EG coverage was more efficient in the use of C and preservation of MOS, combined with a high microbial community, providing better soil quality.
A utilização do solo sob Caatinga tem ocasionado alterações nas suas propriedades, assim como no comportamento e na qualidade da matéria orgânica. Alterações de caráter extrativista, agropastoril e agrícola tem levado esse bioma a uma condição de insustentabilidade, com profundas alterações na dinâmica e no estoque do C e suas frações, atreladas às modificações na comunidade microbiana que exerce importante função na ciclagem de nutrientes no solo. O objetivo do trabalho foi avaliar as alterações no C do solo, suas frações lábeis e recalcitrantes além da atividade e diversidade microbiana em solos sob diferentes coberturas vegetais e históricos de usos. Foram estudadas sete áreas que consistiram em floresta nativa (F) sem ação antrópica, floresta com predominância de angico (AF) e outra com ipê (IP); três áreas convertidas em cultivos agrícolas de capim elefante irrigado (EG), milho irrigado (MI) e milho sem irrigação (M); e uma área de capoeira (NF). Foram coletadas nas diferentes áreas amostras nas profundidades de 0-5, 5-10 e 10-20 cm, respectivamente. Avaliaram-se os estoques totais de C e N, carbono solúvel em água (CSA) e o C mineralizável acumulado aos 32 dias de incubação, as frações oxidáveis do carbono (F1, F2, F3 e F4) e suas frações nas substâncias húmicas do solo (C-FAH, C-FAF e C-HUM), o C da biomassa microbiana, quociente microbiano (qMIC) e a estrutura da comunidade microbiana através da análise de fosfolipídeos de ácidos graxos (PFLA). A conversão da caatinga para o cultivo de milho ocasionou diminuição de 56 e 38% nos estoques de C e N no solo. Os maiores estoques de C foram observados na cobertura AF, enquanto para o N, o M destacou-se com menores estoques deste elemento, sendo também inferior em todas as profundidades para o CSA. O C mineralizável apresentou comportamento linear, observando-se uma redução na média de C mineralizado acumulado de até 21,03% na profundidade intermediária. As coberturas AF, F e IP obtiveram maiores teores de carbono nas frações oxidáveis para todas as profundidades avaliadas. A área AF apresentou maiores teores de C nas formas lábeis. O C das frações húmicas, apresentaram estoques nas frações C-FAF e C-FAH de 3,59 e 3,73 t ha-1, respectivamente para área AF; e 22,64 t ha-1 na fração C-HUM para EG. A área com MI demonstrou maior eficiência na utilização do C pelos microrganismos nas diferentes profundidades. Para o CBM, a cobertura com F obteve maior concentração, com redução de até 78,32% em profundidade. Maiores concentrações de PFLAs totais foram observadas na área EG, com uma maior população de bactérias em relação aos fungos e maior predominância de bactérias gram positivas em relação as gram negativas. As frações F1, CSA e a C-HUM contribuíram de forma mais expressiva para o aumento do estoque de C e N do solo. Áreas convertidas para produção agícola, tem o potencial de alterar as frações do COS e atividade microbiana, sobretudo quando faz o uso de irrigação nesses ambientes. A cobertura EG foi mais eficiente na utilização do C e preservação da MOS, aliada a uma alta comunidade microbiana, proporcionando melhor qualidade do solo.

Abstract In northernmost Fennoscandia, grazing by reindeer (Rangifer tarandus L.) has a substantial impact on the vegetation of boreal forests and arctic-alpine tundra heaths, which are reflected in below-ground processes, such as nutrient mineralization and soil organic matter decomposition. In the present thesis, the effects of reindeer grazing on soil nutrient cycling were studied by comparing grazed situation with an ungrazed control area in ten boreal forests and six arctic-alpine tundra heaths. In boreal forests, reindeer grazing reduced microbial respiration in both the oligotrophic and mesotrophic study areas, indicating a deficiency of labile substrates for the soil microbes due to reindeer grazing. Simultaneously, there was heterogeneity in the impact on nitrogen mineralization rates as at some sites, mineralization was enhanced by grazing. The fertilization effect of urine and faeces can therefore be strong enough a factor to outweigh a reduction in quality of soil organic matter. In the oligotrophic forests, low soil moisture content in the grazed areas could sometimes limit the mineralization rates even when the potential for mineralization was enhanced by grazing. In the tundra ecosystems, there was spatial variation in the impact of grazing on microbial respiration and nitrogen mineralization. Low grazing intensity occurring outside the growing season had a retarding impact on nutrient cycling in both unfertilized, nutrient-poor and fertilized, nutrient-rich conditions. In contrast, a relatively high grazing intensity enhanced the mineralization rates in two nutrient-poor and two nutrient-rich tundra heaths. When three different grazing intensities were compared in one oceanic, nutrient-rich and one continental, nutrient-poor tundra heath, the strongest positive effect of grazing on soil nutrient cycling occurred in the heavily grazed areas. The data do not support the assumption that soil nutrient availability regulates whether herbivores enhance or retard nutrient cycling in the soil. Instead, the net effect of grazing is determined by the balance between the underlying mechanisms that may work at opposite directions. The most important of these mechanisms are the grazer-mediated impact on the decomposability of the dominant vegetation and fertilization by urine and faeces. The duration, intensity and seasonal timing of the grazing seem to be important factors that regulate whether reindeer grazing enhances or retards soil nutrient cycling in each specific area. Due to the high spatial and temporal variation in the effects of grazing observed in this study, it is not possible to generalize the overall impact of grazing. Further study is required in order to determine the exact conditions under which grazing enhances or it retards soil nutrient cycling.

Soil is the world’s 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.

Landscape position and depth in the soil column influence the movement of microbial substrate throughout a catchment, from upslope areas to downslope areas, thereby impacting nutrient cycling rates and capabilities of the microbial communities in those areas. Wildfire also shapes the biogeochemistry of the landscape, creating a mosaic with variations in substrate type and concentration that also influence microbial communities and biogeochemical cycling. Nitrogen (N) in particular is altered by wildfire, as it is easily volatilized and the removal of organic matter (OM) reduces N inputs. We aimed to understand how landscape position and soil depth, first and foremost, influence microbial communities and their N-cycling, but also how this may differ from wildfires and their relative impacts on the soil microbial communities. Landscape position proved to influence few soil and microbial characteristics, while movement from soil surface to deep in the column and the incidence of wildfire caused many variations in soil physical and biogeochemical cycling properties. The interaction of landscape position and soil depth also showed little variation in any measurements, while wildfire and soil depth interactions showed drastic changes that indicate high order controls over the soil microbial community. It can be surmised that while landscape position is important for many soil properties, it is soil depth and wildfire that truly control the soil microbial communities and their N-cycling capabilities.

A aplicação de biossólidos em solos agrícolas e/ou florestais é uma prática aceitável, tanto como forma de disposição destes materiais, quanto de melhorar as características físicas, químicas e biológicas do solo. No entanto, pouco se sabe dos impactos decorrentes desta utilização e dos seus efeitos sobre a estrutura das comunidades microbianas dos solos e sua capacidade metabólica. Assim, o objetivo deste trabalho foi determinar alterações quanti-qualitativas na diversidade metabólica dos microrganismos do solo após a adição de biossólidos e identificar possíveis indicadores de alteração de qualidade do solo. O delineamento experimental constituiu-se de 4 doses de biossólidos da ETE-Franca, equivalentes à 6, 12, 24 e 48 Mg ha-1, mantendo-se um controle sem adição de biossólido. Foram utilizadas 4 repetições por tratamento, compreendendo 20 sub-parcelas. Estas sub-parcelas foram incubadas por 1, 2, 4, 8 e 16 semanas, perfazendo um total de 120 parcelas. Após o período de incubação, amostras de solo foram coletadas para as determinações de pH, C-biomassa, Respiração Basal (RB), Respiração Induzida pelo Substrato (RIS), Quociente Metabólico (qCO2) e Diversidade Metabólica. Houve um aumento transiente do pH nos tratamentos com as maiores doses de biossólido, em relação ao controle. Após 16 semanas de incubação os solos com biossólidos apresentaram pH mais baixo do que o controle sem biossólido. O C-biomassa apresentou comportamento semelhante, com os valores decrescendo e tendendo a estabilização, em relação ao controle sem biossólido. A atividade metabólica com base na RB, RIS e MHM indicou uma indução transiente no metabolismo da microbiota do solo nos tratamentos com as maiores doses de biossólido, tanto no início quanto no final do período de incubação. Os maiores valores de qCO2 nos solos com as maiores quantidades de biossólidos sugerem a ocorrência de condições estressantes para a microbiota e sucessão de populações microbianas. A utilização de substratos de C pela comunidade microbiana foi substancialmente influenciada pela quantidade de biossólido adicionado ao solo e pelo período de incubação. Os maiores valores de Riqueza de Substratos (S) e Diversidade Metabólica (H) observados nos tratamentos que receberam as maiores quantidades de biossólido, no início do período de incubação, são indicativos de um estímulo da microbiota nativa e da contribuição de novas células microbianas decorrentes da adição do biossólido. As similaridades entre os perfis de utilização de substratos C diminuíram com o aumento da concentração de biossólido no solo, em relação ao controle sem biossólido, e aumentaram em função do período de incubação, sugerindo uma indução transiente na diversidade metabólica do solo em função da aplicação de biossólido da ETE-Franca. Solos que receberam altas doses de biossólidos apresentaram atividades metabólicas não observadas no solo sem biossólidos, no início do período de incubação, e perderam algumas atividades no final do período de incubação, em relação ao controle sem biossólido. No geral, os resultados sugerem que a aplicação de biossólidos da ETE-Franca no solo argiloso utilizado provoca um distúrbio na fisiologia da microbiota do solo e que aplicações sucessivas de altas doses de biossólido podem ocasionar alterações significativas na capacidade metabólica dos solos.
The use of biosolids in agricultural and/or forestry soils has been an acceptable practice to dispose as well as to improve physical, chemical and biological soil properties. However, the impacts of biosolids application on microbial community structures and metabolic diversity in agricultural soils are relatively unknown. The aim of this work was to determine quantitative and qualitative alterations in the metabolic diversity of a clay soil upon treatment with biosolids. A clay soil was amended with the equivalent to 6, 12, 24 and 48 Mg ha-1 of biosolids from the City of Franca (SP) Sewage Treatment Plant. A control without biosolids was also used. Four repetitions per treatment were used, totalizing 20 sub-parcels. Sub-parcels were incubated for 1, 2, 4, 8 and 16 weeks, after incorporating the biosolids, totaling 120 microcosms. After the incubation period, soil samples were collected to determine pH, Basal Respiration (BR), Substrate Induced Respiration (SIR), C-biomass, Metabolic Quotient (qCO2) and Metabolic Diversity. A transient increase in soil pH was observed in the treatments with the higher concentrations of biosolids, compared to the control without biosolids. After 16 weeks of incubation, the pH of soils with biosolids was lower than in the control without biosolids. The C-biomass also showed a transient increase in soils with biosolids at early time points, and did not statistically differ from the control at late time points. Transient increases in metabolic activities, based on BR, SIR and AWCD (Average Well Color Development), were observed in soils with the higher concentrations of biosolids at early time points. Higher values of qCO2 in soils with higher concentrations of biosolids at the earliest and latest time points suggests stressing conditions to the microbial community and alterations in microbial community structure. The utilization of C-substrates by the soil microbial community was greatly affected by the concentration of biosolids added and by the incubation time. Higher values of Substrate Richness (S) and Metabolic Diversity (H) in the soils with the higher concentrations of biosolids at early time points indicate that biosolids stimulate the activity of soil microorganisms and contribute with new activities. The similarities between the C-sources utilization profiles in the soil amended with biosolids and the control were lower in soils with the higher concentrations of biosolids. The similarities of C-source utilization profiles in the soils with biosolids and the control increased during the incubation time. Soils amended with the higher concentrations of biosolids showed metabolic activities not observed in the control soil at the early time points. The ability to use several C-sources was lost at the latest time point. In general, the results suggest that the incorporation of biosolids to the clay soil disturbs soil microbial physiology and that the successive application of biosolids to the soil may significantly alter the soil metabolic activities.

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The fertility and microbial activity in soil have been often used to indicate changes in soil quality. The microbial activity directly interacts with environmental conditions, soil types and different agricultural production systems used. Despite advances in this area, it is still a great challenge to define good indicators of soil quality, their interactions and behavior over time. Thus, the aim of this study was to assess the current state of soils under pastures in the western region of São Paulo using the evaluation and correlation of the microbial attributes and soil fertility. We performed on 108 soil samples, collected in settled pastures, analysis of thirteen variables in a laboratory within the microbial attributes, fertility and soil texture. The findings of the evaluation of the microbial demonstrated that microbial biomass had the lowest coefficient of variation, normal distribution of frequency and significantly correlated with most variables analyzed, on the other side, within the attributes of fertility of the soil, pH had the lowest rate variation while the phosphorus content demonstrated large variations with disproportionately high frequency among other variables, indicating the current status of soil degradation. The soil microbial biomass can be considered a good indicator for microbiological evaluation in these soils. The principal component analysis demonstrated that 51% of the variation was concentrated in the axis 1 and 2, which is considered representative for multivariate environmental assessment
A fertilidade e a atividade microbiana em solo têm sido utilizadas com frequencia para indicar mudanças na qualidade do solo. A atividade microbiana interage diretamente com as condições ambientais, classes de solo e diferentes sistemas de produção agrícola utilizados. Apesar dos avanços nesta área ainda é um grande desafio a definição de bons indicadores de qualidade do solo, suas interações e comportamento ao longo do tempo. Desta forma, o objetivo desse estudo foi verificar o estado atual de solos sob pastagens na região oeste paulista utilizando-se da avaliação e correlação de atributos microbiológicos e de fertilidade do solo. Foram realizadas em 108 amostras de solos, coletadas em áreas de pastagens estabelecidas, análises de treze variáveis em laboratório, dentro dos atributos microbiológicos, de fertilidade e granulométrico do solo. Os resultados encontrados na avaliação dos atributos microbiológicos demonstraram que a biomassa microbiana apresentou o menor coeficiente de variação, distribuição normal de freqüência e correlação significativa com a maioria das variáveis analisadas, por outro lado dentro dos atributos de fertilidade do solo o pH apresentou o menor coeficiente de variação enquanto que o teor fósforo apresentou grande variação com freqüência desproporcional indicando junto com outras variáveis o estado atual de degradação do solo. A biomassa microbiana do solo pode ser considerada como bom indicador para avaliação microbiológica nestes solos. A análise de componentes principais apresentou que 51% da variação concentrou-se dentro do eixo 1 e 2 o que é considerado representativa para avaliação ambiental multivariada

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.

The response of UK semi-natural soil and plant communities to long-term inputs of pollutant nitrogen (N) is presently poorly understood. This study aims to investigate the effects of up to 8 years simulated pollutant N additions on plant nutrition and key below ground nutrient cycling processes in an upland heath, an acid grassland and a calcareous grassland. An additional series of plots was established in the grasslands that received short-term N and phosphorus (P) inputs which enabled investigation of NIP interactions and the determination of plant biomass. Soil inorganic N concentrations indicated that all of the sites had become 'N saturated', and that P limitation may be of increasing importance, particularly in the heathland and calcareous grassland. This was confirmed in the calcareous grassland where significant increases in above ground biomass were seen in only P treated plots, while in the acid grassland, there were no growth responses to nutrient additions. A field-based bioassay was developed which demonstrated that both short and long-term inputs of N significantly increased root surface phosphomonoesterase (PME) activity of Plantago lanceolata seedlings. A parallel microcosm-based bioassay revealed a significant relationship between root surface PME activity of Agrostis capillaris and extractable NfLt concentrations (r = 0.86) in the long-term acid grassland plots, indicating that this site may have reached or be approaching N saturation. In response to long-term N additions, soil microbial biomass carbon increased in the heathland, decreased in the acid grassland and remained constant in the calcareous grassland. Chloroform fumigation indicated that microbial biomass P decreased in the acid and calcareous grasslands, while microbial biomass N increased in the heathland and acid grassland in the N treated plots. Soil PME activity was highly sensitive to the N treatments. It increased at all sites and was significantly correlated with extractable inorganic N concentrations (r = 0.71) in the calcareous grassland, indicating close coupling between N saturation and P limitation. This relationship was also seen in the heathland where there was increased utilisation of monoester P sources in standard and customised BIOLOG plates and increased respiration rates in soils amended with organic P compounds. The implications of these results are discussed, with reference to the critical loads concept and to recent research by other workers in similar and contrasting environments.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A rotação de culturas é um processo de cultivo que pode modernizar e aumentar o rendimento da atividade agropecuária de forma sustentável agregando maior qualidade ao solo. Os objetivos deste estudo foram: (I) avaliar o efeito dos sistemas culturais em plantio direto conduzidos em rotação de culturas e monitorar as alterações das propriedades microbiológicas bioindicadoras da qualidade do solo; (II) investigar as mudanças bioquímicas nos solos decorrentes da adição de diferentes tamanhos de resíduos de soja e milho durante o período de incubação. Foram determinados as biomassas microbianas- C, N e P (CBM, NBM e PBM, respectivamente), a atividade respiratória (C-CO2) e das enzimas desidrogenase, fosfatase e urease, conteúdo do carbono orgânico (Corg), carbono solúvel (Csol), fósforo orgânico (Porg), matéria orgânica (MO), potencial de mineralização do N. O quociente metabólico (qCO2) e microbiano (qMIC) do solo foram calculados. Experimento (I): A avaliação foi realizada em amostras de solo coletadas após a colheita das culturas de verão do ano agrícola 2007/2008, na camada de 0-0,15 m de profundidade em um experimento conduzido sob sistema de semeadura direta, por seis anos. O delineamento experimental foi em blocos casualizados com esquema de faixas com três repetições. As sequências utilizadas foram as monoculturas de soja (Glycine max L.) (SS) e de milho (Zea mays L.) (MM) e a rotação de culturas soja/milho (SM). As culturas de inverno foram milho, girassol (Helianthus anuus L.), nabo forrageiro (Raphanus sativus L.), milheto (Pennisetum americanum (L.) Leeke), guandu (Cajanus cajan (L.) Millsp), sorgo (Sorghum bicolor (L.) Moench) e crotalária (Crotalária juncea L.). O conteúdo da biomassa microbiana-C, N e P do solo aumentou significativamente...
Crop rotation is a practice of growing dissimilar plants that can modernize and increase the farm economy in a sustainable form for adding more quality to the soil. The aims of this study were: (I) evaluate the effect of crop sequences under no-tillage systems on changes in the soil microbiological properties; (II) investigate the biochemistries changes during the incubation of the soil added with different sizes particles of soybean and corn. There were determined the contents of microbial biomass-C, N and P, the production of C-CO2, the activities of the enzymes dehydrogenase, urease and phosphatase, the organic carbon (Corg), soluble carbon (Csol), organic phosphorous (Porg) and organic matter (MO) contents and the potential of mineralization N. The soil metabolic (qCO2) and microbial (qMIC) quotients were calculated. Experiment (I): The evaluation was performed in soil samples collected after the summer crops harvest, on 2007/2008 growing season, at 0-0.15 m soil depth layer on an experiment conducted under no-tillage system through six years. The experimental had a completely randomized block design, in strips plots with three replications. The crop sequences were continuous soybean (Glycine max L.) (SS), continuous corn (Zea mays L.) (MM), and crop rotation soybean/corn (SM). Winter crops were corn, sunflower (Helianthus anuus L.), radish (Raphanus sativus L.), pearl millet (Pennisetum americanum (L.) Leeke), pigeon pea (Cajanus cajan (L.) Millsp), grain sorghum (Sorghum bicolor (L.) Moench) and sunn hemp (Crotalária juncea L.). The content of microbial biomass-C, N and P in the soil increased significantly in crop sequence SM compared to continuous crop. The interactions SM-millet and MMsorghum influenced the content of biomass-C, SM-hemp and SM-millet in the biomass-N content... (Summary complete electronic access click below)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O aporte de N na forma assimilável pelas plantas (NH4+) em diversos ecossistemas é realizado principalmente pelos organismos diazotróficos, e os mesmos vêm sendo pesquisados amplamente em todo o mundo. O N se configura como um dos nutrientes que apresenta grande importância no crescimento e desenvolvimento das plantas devido a sua função estrutural, pois faz parte da molécula de compostos orgânicos,como os aminoácidos e proteínas, sendo ainda ativador de muitas enzimas. Os adubos amoniacais são os mais comumente utilizados como fonte de nitrogênio nas atividades agrícolas. Contudo, a sua utilização acarreta em aumentos significativos da acidificação do solo, provenientes dos processos de nitrificação. O solo é um sistema complexo e as práticas de manejo podem afetar significativamente as comunidades microbianas que realizam muitos processos de suma importância para a produtividade e sustentabilidade. O objetivo desse trabalho foi avaliar o impacto na comunidade microbiana de um solo com a adição de N e calagem sob cobertura na aveia preta em um sistema de plantio direto de longa duração. As coletas de solo foram realizadas em cinco tratamentos distintos, distribuídos aleatoriamente em triplicatas na área experimental: SC (sem cobertura de inverno); CC (com cobertura de inverno); CC+ N (com cobertura de inverno + nitrogênio); CC+C (com cobertura de inverno + calcário) e CC+C+N (com cobertura de inverno + calcário + nitrogênio). Avaliaram-se os atributos químicos do solo, o carbono da massa microbiana, a respiração basal, o quociente metabólico, o NMP dos diazotrofos, o número de nódulos, a massa seca dos nódulos, a massa seca da raiz e parte aérea da soja, bem como utilizou-se a técnica da Biolog Ecoplate para analisar o consumo de fontes de carbono entre os tratamentos, a fim de verificar suas similaridades e diferenças. Constatou-se que as condições químicas como o pH influenciaram diretamente o crescimento e o desenvolvimento da comunidade microbiana em vários parâmetros estudados. Os níveis de carbono da massa microbiana do solo, bem como a respiração basal e o quociente metabólico variaram entre os tratamentos, sendo o tratamento CC+ N o que apresentou um maior distúrbio na biomassa microbiana causado pelo seu manejo. Em relação às bactérias diazotróficas do solo, ficou evidente que a população teve forte influência da aplicação de N e de calcário, se mostrando nula no tratamento CC+C+N, contudo a população de bactérias noduladoras não teve influência negativa nos diferentes tratamentos.Observou-se que o houve um consumo diferente pelas comunidades de para determinados subgrupos de fontes de carbono. É notável a importância do estudo acerca das características e potenciais das bactérias diazotróficas, a fim de promover um avanço nas tecnologias para maximizar a produtividade de culturas que apresentam grande valor econômico para os produtores.
The contribution of N in the form assimilable by the plants (NH4 +) in several ecosystems is carried out mainly by the diazotrophic organisms, and they have been researched widely around the world. N is one of the nutrients that has great importance in the growth and development of plants due to its structural function, since it is part of the molecule of organic compounds, such as amino acids and proteins, being still activator of many enzymes. Ammoniac fertilizers are most commonly used as a source of nitrogen in agricultural activities. However, their use leads to significant increases in soil acidification from nitrification processes. Soil is a complex system and management practices can significantly affect microbial communities that perform many processes of paramount importance for productivity and sustainability. The objective of this work was to evaluate the impact on the microbial community of a soil with the addition of N and liming under cover in black oats in a long - term no - tillage system. Soil samples were collected in five different treatments, randomly distributed in triplicates in the experimental area: SC CC (without winter cover); CC (with winter cover); CC + N (with winter + nitrogen coverage); CC + C (with winter cover + limestone) and CC + C + N (with winter cover + limestone + nitrogen).Soil chemical, microbial mass carbon, basal respiration, metabolic quotient, diazotrophs NMP, number of nodules, nodule dry mass, dry mass of the root and shoot of the soybean were evaluated, as well as using the Biolog Ecoplate technique to analyze the consumption of carbon sources between treatments in order to verify their similarities and differences. It was found that chemical conditions such as pH directly influenced the growth and development of the microbial community in several parameters studied. The carbon levels of the soil microbial mass, as well as the basal respiration and the metabolic quotient varied among the treatments, being the treatment CC + N that presented a greater disturbance in the microbial biomass caused by its handling. In relation to the diazotrophic bacteria of the soil, it was evident that the population had a strong influence of the application of N and limestone, if it was null in the treatment CC + C + N, however the population of nodulating bacteria did not have negative influence in the different treatments. It was observed that there was a different consumption by the communities of for certain subgroups of carbon sources. The importance of the study of the characteristics and potentials of diazotrophic bacteria is remarkable in order to promote an advance in the technologies to maximize the productivity of crops that present great economic value to the producers.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O manejo agrícola altera, em muito, as características físicas, químicas e biológicas dos solos. A cultura e as condições climáticas, assim como o tipo de solo propriamente dito, afetam a decomposição da matéria orgânica do solo e, consequentemente, a biogeociclagem dos nutrientes. A matéria orgânica é uma característica importante em relação à fertilidade do solo, de modo que o impacto do uso do solo precisa ser avaliado principalmente em agroecossistemas. O conhecimento dos efeitos do uso da terra e das práticas agrícolas sobre a comunidade microbiana é de fundamental importância, em vista das importantes funções que os microorganismos desempenham no solo e que irão se refletir na produtividade agrícola. Neste sentido, uma avaliação da biomassa microbiana e de microorganismos do solo pode evidenciar diversas alterações no ecossistema do solo que estão associadas ao teor de argila e/ou sistemas de plantio. No presente estudo, caracterizou-se a camada superficial do perfil de solos sob plantio direto e plantio convencional em quatro fazendas no Brasil em relação a alguns de seus componentes microbiológicos. Para tanto, analisou-se, mensalmente, a respiração do solo, a biomassa microbiana e grupos de microorganismos. A avaliação da biomassa microbiana foi feita através da técnica da fumigação-incubação (FI), utilizando-se a Equação: [(C-CO2 liberado pelo solo fumigado, no período de 0-10 dias de incubação) - (C-CO2 liberado pelo solo não-fumigado, ao longo de 10-20 dias de incubação)]/0,45. Os cálculos indicaram um conteúdo de carbono da biomassa microbiana significativamente maior nos solos sob sistema de plantio direto em relação àqueles sob plantio convencional, na camada amostrada (0-10 cm de profundidade). Quantidades significativamente maiores...
The crop management changes greatly the physical, chemical and biological soil properties. Furthermore, the crop and soil types, and the climatic conditions would affect on soil organic matter decomposition and on nutrients biogeociclying. Soil organic matter is a important characteristic in relationship soil fertility. The knowledge about effects on soil using and agriculture practices on soil microbial communities is very important, due to the function that microorganisms have in soil and it was going to in soil fertility. In this sense, evaluation of the soil microbial biomass and micro-organisms greatly aids predictions several changes in the soil ecosystems are associated with reduced tillage as compared with conventional tillage. Surface soils from long-term no-till and conventional tillage plots at four Brazil farms were characterised for microbial components. Soil respiration, microbial biomass carbon and counts of microorganisms were measured at intervals monthly. The evaluation of microbial biomass carbon was done by fumigation-incubation technique (FI). For calculating the soil microbial biomass carbon, the equation used was: Equation = [(CO2-C evolved by fumigated soil, 0-10 days) - (CO2-C evolved by unfumigated soil, 10-20 days)]/0,45. Significantly greater amounts of CO2-C were released from no-till than from conventional tilled soils. qCO2 values were not significantly different between tillage systems. This observation confirms that the tillage affected biological activity in those soils, further that qCO2 values didn't have significantily different which two tillage systems, in studied soils. Number both fungi and bacteria were assayed by Most Probable Number (MPN) by the agar drop counting technique and the microorganisms groups were calculated using by traditional Most Probable Number (MPN) method...(Complete abstract, click electronic access below)

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The conversion of native vegetation áreas into pastures may contribute to the emission of greenhouse effect gases, due to the soil use change. The use of silvopastoral systems, which integrate legume tree species and grasses, may be a viable option to mitigate these emissions and increase soil carbon and nitrogen stocks. This work aimed to evaluate carbon stock (EC) and microbial activity in silvopastoral systems in the Forest Zone of Pernambuco. To this end, soil samplings were done at the dry and rainy seasons in an experiment evaluating signal grass (Brachiaria decumbens Stapf) with sabiá (Mimosa caesalpiniifolia Benth) or gliricidia (Gliricidia sepium (Jacq.) Steud.). Soil samples were taken up to 100 cm depth at 0, ,4 and 8 m from the legume strip, and up to 20 cm at 0,2,4,6 e 8 m from the legume strip for biological analysis. Total organic carbon (COT), total nitrogen (NT), soil organic matter chemical fractioning (fractions fulvic acid – AF; humic acid – AH and humin –HUM), soil density, microbial biomass carbon (Cmic), soil basal respiration (RBS) were determined and metabolic quocient (qCO2) and carbon stock (EC) were calculated. There was no significant difference (p>0.10) for Cmic for the distances from the legume strip at the rainy season. Significant difference was found for RBS at the rainy season for legume strip distances and soil depth layers. There was no significant difference (p >0.10) for Cmic between legume strips distances for the rainy season, while there was significant differences (p<0.10) for RBS between legume strip distances and soil layers. At the dry season, the highest qCO2 was at the 0-10 cm layer, 2 m away from the legum strip. There was significant difference between systems and legume strip distances for COT at the dry season, with the highest contents at 8 and 4 m for gliricidia and sabiá, respectively. EC had significant differences (p<0.10) between soil layers at the dry season, with higher values at the 20-60 layers, while at the rainy season there was only a significant difference at the 0-10 layer at 8 m from the legume strips, when sabiá values were 33% higher than gliricidia ones. Significant difference (p<0.10) was found for NT between layers on both seasons, with higher values going from the upper to the deeper layers. In general the AF fraction was the smallest, with higher values for all three fractions (AF, AH and HUM) for sabiá. Biological activity, as represented by Cmic and RBS, confirmed the silvopastoral systems capability of maintaining soil microbiota. The the higher C content in more stable fractions in sabiá indicates it to be more efficient in carbon sequestration. The silvopastoral system had EC similar to other cropping systems, but it might increase in a longer term of evaluation.
A conversão de áreas de vegetação nativa em pastagem pode contribuir para a emissão de gases de efeito estufa, ocasionada pela mudança no uso do solo. O uso de sistemas silvipastoris, que integram espécies arbóreas leguminosas e gramíneas, pode ser uma opção viável para mitigar essas emissões com aumento do estoque de carbono e nitrogênio no solo. O objetivo do trabalho foi avaliar o estoque de carbono (EC) e atividade microbiana em sistemas silvipastoris na Zona da Mata de Pernambuco. Para isso foi realizada coleta de solo nos períodos seco e chuvoso em experimento avaliando consórcios de braquiária (Brachiaria decumbens Stapf.) com sabiá (Mimosa caesalpiniifolia Benth) ou com gliricídia (Gliricidia sepium (Jacq.) Steud.). Foram retiradas amostras de solo até 100 cm de profundidade aos 0,4,e 8 m de distância da faixa da leguminosa, e até os 20 cm em pontos com 0,2,4,6 e 8 m de distância da faixa da leguminosa para análises biológicas. Foram determinados carbono orgânico total (COT), nitrogênio total (NT), fracionamento químico da matéria orgânica do solo (fração ácido fúlvico-AF; ácido húmico-AH e humina-HUM), densidade do solo, carbono da biomassa microbiana (Cmic), respiração basal do solo (RBS) e calculado o quociente metabólico (qCO2) e estoque de carbono (EC). Não houve diferença significativa (p>0,10) para Cmic entre distâncias da faixa da leguminosa no período chuvoso. A RBS apresentou diferença significativa (p<0,10) no período chuvoso entre distâncias da faixa da leguminosa e camadas. No período seco, o maior valor de quociente metabólico (qCO2) ocorreu na camada de 0-10 cm, na distância 2. Houve diferença significativa entre sistemas e distâncias da faixa da leguminosa para COT no período seco, com os maiores teores nas distâncias 8 e 4, para gliricídia e sabiá, respectivamente. Houve diferença significativa (p<0,10) entre camadas no EC no período seco, com maior estoque nas camadas de 20-60 cm. No período chuvoso observou-se maior uniformidade do EC, com diferença significativa apenas na camada de 0-10 cm na posição 8 com sabiá 33% superior. Para NT ocorreu diferença significativa (p<0,10) entre camadas com teores que variaram nos dois períodos avaliados, com maior concentração nas camadas superficiais reduzindo em profundidade. Para o fracionamento químico, no geral, a fração AF apresentou os menores teores de C, com os maiores teores das três frações (AF, AH e HUM) no consórcio com sabiá. A atividade biológica refletida pelos valores de Cmic e RBS comprovou a capacidade dos sistemas silvipastoris em sustentar a microbiota do solo. Os maiores teores de C nas frações mais estáveis no consórcio com sabiá o destacou com maior eficiência de reter carbono. O sistema silvipastoril apresentou EC semelhante a outros sistemas de manejo, mas não se descarta possibilidade de maior retenção de C em uma avaliação do experimento a longo prazo.

The purpose of this study was to investigate the results of two long-term fertilization experiments on soil organic C, total N, and mineralizable N in the Jiangsu Province of People's Republic of China. The soil samples that received manure over the years contained more soil organic C, and total N than the inorganic fertilized samples. Soil organic C was closely correlated with total N and there were correlations between crop yields and soil organic C contents and between crop yields and soil total N contents. Plant-available N was estimated using biological and chemical tests. Mineralized N formed under anaerobic incubation was low except for those soil samples that received manure. Microbial biomass C and N were estimated using the chloroform fumigation-incubation method (CFIM) and fumigation-extraction procedures. Biomass measurements by CFIM were more precise and reliable than values obtained by fumigation-extraction. Treatment differences in biomass were not significant. Estimates of biomass C and N were influenced by the choice of the control soil and the period of incubation used by the CFIM. Unfumigated (10-20 d) control soils were found to be the best control for samples. Extraction of mineralized N using O.5M NaHCO$ sb3$ after incubation overestimated biomass N since this extraction was found to extract non-biomass N.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Characterized as extremely important, the soil is a complex environment and it shelters a great diversity of microorganisms. However, little is known about the diversity and ecology of the soil microbiota. Thus, the first part of this dissertation reviews the methodological evolution used to characterize the diversity and abundance of microorganisms found in soil. The second part consists of the application of two methodologies reviewed in the previous chapter, serial dilution and solid medium plating, to estimate free-living nitrogen fixing microorganisms, and fumigation-extraction to estimate soil microbial biomass (BMS). The last part employs the most modern microbial soil characterization technique, the metagenomics of 16S rRNA. Hence, our initial hypothesis was that sugarcane fields’ soils would have better soil microbiological indicators than grasslands’ soils. The results confirmed that the hypothesis was partially correct, and it was possible to find about 140% more free-living diazotrophic colony-forming units (CFUs) and a 17% richer alpha diversity in sugarcane fields’ soils than in grasslands’ soils. The beta diversity between sugarcane plantations and pastures presented clear differences. However, sugarcane fields’ soils obtained about 25% less BMS than grasslands’ soils. In relation to the bacterial phyla, the grasslands have more Actinobacteria, Chloroflexi and Planctomycetes and sugarcane fields have a greater number of TM7 and bacteria that were not identified, being Proteobacteria and Acidobacteria the dominating phyla in both types of soil. Although the results of nitrogen fixers and microbial biomass appear to be conflicting, it is an indication that the diazotrophic community undergoes with a diverse biotic and abiotic influences than the total community of soil microorganisms, and thus respond differently.
Caracterizado como de extrema importância, o solo é um ambiente complexo e que abriga uma grande diversidade de micro-organismos. Entretanto ainda pouco se sabe sobre a diversidade e ecologia da microbiota do solo. Deste modo, a primeira parte desta dissertação revisa a evolução metodológica empregada para caracterizar a diversidade e abundância dos micro-organismos encontrados no solo. A segunda parte consiste na aplicação de duas metodologias revisadas no capítulo anterior, a de diluição seriada e plaqueamento em meio sólido, para estimar micro-organismos fixadores de nitrogênio de vida-livre, e a fumigação-extração, para estimar a biomassa microbiana do solo (BMS). E a última parte emprega a técnica mais moderna de caracterização das comunidades microbianas de solo, a técnica de metagenômica de 16S rRNA. À vista disso, a nossa hipótese inicial era que solos de canavial teriam indicadores microbiológicos de solo melhores do que solos de pastagem. Os resultados comprovaram que a hipótese estava parcialmente correta, sendo possível encontrar cerca de 140% a mais de Unidades Formadoras de Colônias (UFCs) de diazotróficos de vida-livre e uma diversidade alfa 17% mais rica em solos de canaviais do que em solos de pastagens. A diversidade beta entre canaviais e pastagens apresentou diferenças nítidas. Entretanto, os solos de canaviais obtiveram cerca de 25% a menos de biomassa microbiana do solo do que solos de pastagens. Em relação aos filos bacterianos, os pastos possuem mais Actinobacteria, Chloroflexi e Planctomycetes e canaviais possuem maior número de TM7 e bactérias que não foram identificados, sendo Proteobacteria e Acidobacteria os filos dominantes nos dois tipos de solo. Apesar de parecerem conflitantes os resultados de fixadores de nitrogênio e biomassa microbiana, é um indicativo de que a comunidade de diazotróficos sofrem influências bióticas e abióticas diversas do que a comunidade total de micro-organismos do solo, e desta forma, respondem de forma diferente.

A matéria orgânica e a biomassa microbiana do solo consistem em sensíveis indicadores de qualidade do solo e de seus estoques de carbono e nitrogênio que, juntamente com a textura, têm auxiliado na escolha de formas de manejo agronômico mais sustentáveis. Os métodos disponíveis para a determinação da matéria orgânica (Walkley-Black modificado da EMBRAPA SOLOS, 1997) e da biomassa microbiana (Vance et al., 1987a) têm sido largamente utilizados, porém possuem alguns inconvenientes como a geração de resíduos altamente tóxicos e a grande demanda de tempo para analisar um pequeno número de amostras. A espectroscopia, por sua vez, tem se mostrado uma alternativa mais rápida e limpa para a identificação e quantificação de compostos orgânicos. Por esse motivo, este trabalho teve como objetivo testar métodos espectroscópicos, tanto no infravermelho próximo (NIRS) quanto no médio com refletância difusa (DRIFTS), com o uso de calibração multivariada, para a quantificação destes indicadores. Os teores de argila, silte, areia, carbono orgânico total e carbono microbiano, assim como o quociente microbiano (CMIC/COT), foram espectrometricamente preditos de modo satisfatório. Em geral, obtiveram-se melhores resultados utilizando DRIFTS.
Organic matter and microbial biomass are sensible ways to indicate soil quality as well as carbon and nitrogen stocks. These properties, added to clay, silt and sand contents, have been helped to choose sustainable agronomic soil managements. Current methods for organic matter (Walkley-Black modified by EMBRAPA SOLOS, 1997) and microbial biomass (Vance et al., 1987a) determinations have been widely used despite the generation of toxic waste and large time requirement for analyzing a small number of samples. Spectroscopy, in turn, has been shown a clean and rapid alternative method for this purpose. Thus, the aim of the study was to evaluate the near-infrared reflectance spectroscopy (NIRS) and the mid-infrared diffuse reflectance spectroscopy (DRIFTS) on soil organic matter, microbial biomass and texture determination. Clay, silt, sand, total organic carbon and microbial carbon contents as even as microbial quotient are accurately quantified by infrared spectroscopy. In general, DRIFTS provided better results.

A mudança do uso da terra modifica os ciclos dos elementos no solo, com alterações nos fluxos dos gases do efeito estufa (GEE). O tempo de implantação do sistema plantio direto associado a uma planta de cobertura (SPD) pode recuperar o estoque de carbono (C) no solo e mitigar o aumento da temperatura global devido à elevação da concentração dos gases do efeito estufa. Assim, o objetivo deste trabalho foi avaliar as alterações nos estoques de C e N do solo com o tempo de implantação do SPD tomando como referência absoluta a condição original (Cerradão) e, também com referencia relativa áreas com mudança do uso da terra, uma sob pastagem, e outra sob plantio convencional. O estudo foi realizado em áreas situadas no município de Rio Verde-GO (17º50\' a 18º20\' S e 51º43\' a 50º19\' O), em um Latossolo Vermelho distrófico com teores de argila entre 50 e 70 %. O delineamento experimental empregado foi inteiramente casualisados com parcelas subdivididas, constando de doze áreas, estas divididas em três sub-áreas cada qual com seis pontos de amostragem e cinco profundidades (0-5, 5-10, 10-20, 20-30 e 30-40 cm). As áreas amostradas foram três sob Cerradão (CE, 2CE e 3CE); uma sob pastagem (PA), uma sob plantio convencional (PC), e sete em SPD com uma área de conversão do plantio convencional para o SPD (PD 0) e áreas com 4, 5, 7, 8, 10 e 12 anos de implantação do sistema (PD 4, PD 5, PD 7, PD 8, PD 10, PD 12). As variáveis estudadas foram: os atributos físicos e químicos, os estoques de C e N e a composição isotópica do 13C/12C e 15N/14N. Os fluxos dos GEE (CO2, N2O e CH4) foram determinados no CE, PA PC e PD com 8, 10 e 12 anos, além das quantidades de N-inorgânico e C e N-microbiano. Os resultados deste estudo mostraram que o SPD promoveu melhoria nos atributos físicos como a redução da compactação do solo, e nos atributos químicos como o aumento do pH e da disponibilidade de K, P, Ca e magnésio nas camadas superficiais do solo. Os estoques de C e N foram maiores nas áreas sob Cerradão (80 e 4 Mg ha-1, respectivamente para o C e N). Os menores valores nos estoques de C foram reportados no PD 0, PC e PA (54; 62 e 64 Mg ha-1, respectivamente). O tempo de implantação do SPD aumentou o estoque de C no solo, de modo que no PD 12 foi encontrado estoque de C igual as áreas sob Cerradão. A taxa anual de acúmulo de C no SPD foi calculada em 1,26 Mg ha-1 ano-1 (0-40 cm). As quantidades médias de C e N-microbiano e N-inorgânico foram encontradas no CE, o Nnitrato correspondeu a 60 % do total em todas as áreas. A maior emissão total em Cequivalente foi observado na PA (160 kg ha-1 ano-1), no CE foi de 135 kg ha-1 ano-1, enquanto que para o PC e SPD as emissões foram de 121 e 129 kg ha-1 ano-1, respectivamente. O seqüestro de C no solo sob SPD para a situação avaliada foi de 1,13 Mg ha-1 ano-1. O SPD mostrou neste estudo, que é uma prática agrícola que melhora as condições do solo, promovendo o aumento no estoque de C sem o aumento nas emissões de N2O e CH4 podendo tornar-se uma alternativa para mitigar as emissões dos GEE, garantindo a sustentabilidade do sistema produtivo
The land-use change transforms the elements cycles in the soil, with alterations in the greenhouse gas (GHG) emissions. The time of implementation of the no-tillage system associated with a cover crop (NT) can recover the carbon (C) stocks in the soil and thus mitigate the global temperature increase due increasing GHG concentration. Therefore, the objective of this work was to evaluate the alterations of the soil carbon and nitrogen stocks following implementation time of no-tillage (NT) system taking as absolute reference the original condition (Cerradão) and, also, as relative reference, areas with other land use change, one under pasture, and other under conventional tillage. The study was done in areas located at Rio Verde (Goias state, Brazil) (17°50\' to 18°20\' S and 51°43\' to 50°19\' W), in a Oxisol (very clayed Red Dystrofic typic Latosol) with clay contents in the range 50 - 70 %. At each site, samples were taken randomly with subdivided parcels; these sites were divided in three sub-areas with six sampling locations and five depths (0-5, 5-10, 10-20, 20-30, 30-40 cm.). The sampled sites were three under ?Cerradão? (CE, 2CE and 3CE); one pasture (PA), one conventional tillage (CT), and seven situations under no-tillage system with an area recently converted from conventional tillage to no-tillage (NT 0), and areas with 4, 5, 7, 8, 10 and 12 years of implementation of the no-tillage (NT-4, NT-5, NT-7, NT-8, NT-10 and NT- 12). The variables studied were: physical and chemical attributes, the C and N stocks and the isotopic composition of 13C/12C and 15N/14N. The GHG emissions (CO2, N2O and CH4) were measured in CE, PA, CT and NT with 8, 10, and 12 years together with the quantity of inorganic-N and microbial C and N. The results of this study showed that these no-tillage systems guaranteed the physical attribute improvement with the decrease of the soil compaction and in the chemical attributes with increase of pH and of the availability of K, P, Ca and magnesium in the soil superficial layers. The carbon and nitrogen stocks were higher in ?Cerradão? (80 and 4 Mg ha-1, respectively to C and N). The lowest values in the carbon stocks were reported in NT-0, CT and PA (54; 62 and 64 Mg ha-1, respectively). The implementation time of no-tillage (NT) system increased the carbon stock in the soil, leading to carbon stock in the NT-12 area in the same level of the ?Cerradão? areas. The annual soil C accumulation in the NT system was calculated in 1,26 Mg ha-1 yr?1 (0-30 cm). For all areas, the average quantities of C and microbial-N and inorganic-N were found in CE, nitrate-N corresponded 60 % of the total. The highest total emission in C-equivalent was observed in PA (160 kg ha-1 yr-1), in CE it was 135 kg ha-1 yr-1, and amounted 121 and 129 135 kg ha-1 yr-1 for the CT and NT respectively. The carbon sequestration in the soil under (NT) for the studied situations was 1,13 Mg ha-1 yr-1. The No-tillage (NT) system studied showed to be an agricultural practice that improves the soil condition, promoting the increase of carbon stock without the increase of N2O and CH4 emissions, being thus an alternative to diminish the GHG emissions, and guaranteeing the sustainability of the productive system

The structure and function of microbial communities are critical to the maintenance and sustainability of terrestrial ecosystem processes. Consequently, there is substantial interest in assessing how microbial communities respond to various land management practices, and if alterations to the characteristics of microbial communities has the potential to disrupt ecosystem processes. This thesis was conducted to identify the long term effects of fertilisation and different levels of post-harvest organic matter removal on the characteristics of the FH litter and soil microbial communities in six, second rotation Pinus radiata plantation forests located around New Zealand. The six sites, established between 1986 and 1994, were sampled in 2002 and 2003. Various physical and chemical properties of the sites were measured, and litterfall production was determined. The microbial biomass in the FH litter layer and soil was determined by chloroform fumigation-extraction, and Biolog plates were used to assess the relative differences in microbial community diversity, based on patterns of substrate utilisation. Fertilisation substantially altered the physical and chemical properties of the forest floor, including FH litter moisture content, mass, carbon content, nitrogen content and carbon: nitrogen ratio and soil pH, nitrogen content and carbon: nitrogen ratio. The same range of FH litter and soil properties were also significantly changed by different levels of organic matter removal. The biomass and diversity of the FH litter and soil microbial communities were significantly altered by fertilisation and organic matter removal, and the differences in the microbial community characteristics were significantly correlated to the effects of the fertilisation and organic matter removal treatments on the physical and chemical environment in the majority of cases. The physical and chemical properties of the sites were significantly correlated to estimates of wood production, and it was also found that the characteristics of the microbial community were strongly related to productivity at several sites. The results demonstrated that fertilisation and organic matter removal regimes have had long term effects on the microbial communities at the sites. The persistence of the effects of the organic matter removal treatments were particularly noteworthy, as these treatments were applied at site establishment, and despite no subsequent reinforcement over the life of the trials, were still substantially influencing the physical, chemical and microbiological properties of the FH litter and soil up to 17 years later. The results of this thesis also emphasised the value of long-term experiments in assessing the effects of disturbance on the physical, chemical and microbiological characteristics of forest ecosystems. Further research into the specific nature of the relationship between site productivity and microbial community characteristics was suggested as an important focus for future studies.

It is well documented that increases in soil organic matter (SOM) improve soil physical properties and increase the overall fertility and sustainability of the soil. Research in SOM storage has recently amplified following the proposal that agricultural soils may provide a significant carbon (C) sink that may aid in the mitigation of increasing atmospheric carbon dioxide. Observed differences in lint yield and nitrogen response from a cotton performance study at the Texas A&M University Experimental Farm near College Station, TX prompted us to examine the effects of tillage and rotation on soil organic C (SOC), soil microbial biomass C (SMBC), 38-day cumulative C mineralization (38-day CMIN), hot-water extractable organic C (hot-WEOC), carbohydrate C, and total glomalin. The treatments examined included conventional-till continuous cotton (CT), reduced-till continuous cotton (RT), and conventional-till cotton after corn rotation (CC) treatments. In pre-plant soil samples, SOC, SMBC, and 38-day CMIN in the top 5 cm were 33, 58, and 79 % greater in RT and 29, 32, and 36 % greater in CC vs. CT. Comparable differences were observed for hot-WEOC and carbohydrate C. Little seasonal variation was observed for labile-C pools throughout the growing season, suggesting minimal C input from cotton roots. Water-stable aggregation was not significantly affected by management, and did not correlate with labile-C pools or total glomalin. Labile-C pools were generally more responsive to management vs. SOC and were strongly correlated with one another. Carbohydrate C of hot-water extracts exhibited the strongest relationships with SMBC and 38-day CMIN, even though it comprised only 3 and 5 % of these pools, respectively. Our data suggest that increasing SOC in Texas cotton-cropping systems through conservation management is possible. Long-term data are still needed to fully address SOC storage potentials in Texas, but increases in labile-C pools resulting from conservation management are attainable and have the potential to positively impact soil fertility.

As agrarian society developed, the most fertile soils able to sustain the nutritional requirements needed for high crop yield were assigned to farming, while the more penurious soils were left to uphold the forest ecosystems. Some temperate forests are developed on acidic soils considered to be nutrient poor, as much of the inorganic nutrients are entrapped in poorly weatherable soil minerals and not easily accessed by plant roots. In an undisturbed ecosystem, the largest contribution of available nutrients comes from the recycling of organically bound nutrients via the decomposition of dead plant material. If biomass is removed, for instance with a more intensified exploitation of the forest ecosystems including whole tree harvesting, this source of nutrients is consequently decreased. The importance of soil mineral weathering as a source of nutrients, and especially that promoted by soil biota, is thereby emphasized. This thesis addresses biotic parameters associated with mineral weathering. Different aspects of soil solution sampling strategies and analysis of different organic ligands as well as biomarkers for the estimation of fungal biomass were investigated. These chemical parameters were also evaluated as indicators of microbial activity in relation to mineral nutrient availability in soil. With the assumption that the current nutrient status of a soil will affect the microbial interest of certain minerals as sources of inorganic nutrients, a mineral amendment trial was performed in a Swedish boreal forest soil. Overall, the amended soil presented good nutrient status, but with a possible shortage of iron. Due to this, it was hypothesized that the amended mineral with the highest iron content i.e. biotite would cause an elevation of microbial activity in its vicinity when compared to the bulk soil. The level of microbial activity in the vicinity of the amended minerals was evaluated via quantification of organic acids and siderophores, as well as estimation of fungal biomass and enzymatic activity. The highest microbial activity was measured for the O horizon of the investigated podzol, although nothing indicated an elevated association with the amended minerals. In the E horizon, however, elevation in microbial activity was observed in the vicinity of the biotite mineral when compared with bulk soil, although only a few of the investigated parameters differed significantly when evaluated separately.   To enable this study, a highly sensitive analytical method employing liquid chromatography and mass spectrometry was developed to quantify a number of hydroxamate siderophores. On-line pre-concentration enabled detection of these organic ligands in the pico-molar range – a necessity when analyzing natural samples. Furthermore, an analytical method was developed for the estimation of fungal biomass via quantification of chitin-derived glucosamine, which also employed liquid chromatography and tandem mass spectrometry. Unlike currently available methods, the one presented in this thesis did not involve analyte derivatization, which resulted in high sample throughput while simultaneously avoiding complications involved with the additional derivatization procedure. The distribution of a group of organic ligands known as aromatic low molecular mass organic acids was also studied in a boreal forest podzol soil. Different sampling and samples preparation techniques, namely tension-lysimeters, soil centrifugation and liquid-soil extraction, were compared when analyzing soil solution components. Significant differences in analyte amount and species type were found between these sampling techniques. Some of the differences could be accounted for by variation in soil composition at different depths of the investigated podzol, but others could be attributed to structural differences within the studied analyte group. This clearly illustrated the intricacy of sampling and analysis when working with a sample matrix as complex and diverse as soil. As previously, liquid chromatography and mass spectrometry was used to quantify the analytes of interest. A highly sensitive analytical method was developed that was able to detect eleven aromatic low molecular mass organic acids in the nano-molar range. High selectivity was ensured by applying multiple reaction monitoring enabled by collision induced fragmentation of the analytes.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The cultivation of natural rubber can be an important alternative to planting large tracts of land degraded in the country, as they have good development in Oxisols, accumulating organic matter and improving nutrient cycling. Therefore the objective of this study was to evaluate through chemical and biological soil attributes, the potential of rubber in the balance, in stock and cycling of nutrients. For this, we studied a chronosequence consisting of a primary forest of reference and areas of rubber trees planted 5, 18, 19, 20 and 44 years ago, where it was taken five soil samples in each area, in 0-10 cm, 11-20 cm and 21-40 cm of depth, in this samples were determined the soil fertility, microbial biomass, organic matter fractionation and enzymatic activity. The results showed that removal of the forest resulted in an average reduction of 46% of the stock of organic carbon in soil, with respect to microbial biomass carbon, this reduction was 32%, regardless of age of the plantation. There was a predominance of the humin fraction, followed by humic and fulvic acids and enzyme activity was higher in soil under primary forest. The succession of primary forest to rubber plantations cause an increase in the microbial activity and does not make much change to the soil fertility. After 18 years of the cultivation there is recovery of half of the content of organic soil matter.
A heveicultura pode constituir importante alternativa de plantio para grandes extensões de terras degradadas pelo País, pois possuem bom desenvolvimento em Latossolos, acumulando matéria orgânica e melhorando a ciclagem de nutrientes. Por isto, o objetivo desse trabalho foi avaliar através de atributos químicos e biológicos do solo, o potencial da seringueira no equilíbrio, no estoque e na ciclagem de nutrientes. Para isso, foi estudada uma cronossequencia formada por uma floresta primária de referência e em áreas de cultivo de seringueira (Hevea spp.) plantadas há 5, 18, 19, 20 e 44 anos, onde foram coletadas cinco amostras de solo em cada área, nas profundidades 0-10 cm; 11-20 cm e 21-40 cm, nas quais foram determinada a fertilidade do solo, biomassa microbiana, fracionamento da matéria orgânica e atividade enzimática. Os resultados mostraram que a remoção da floresta ocasionou em diminuição média de 46% do estoque de carbono orgânico no solo, com relação ao C da biomassa microbiana, essa redução foi de 32%, independente da idade do seringal. Verificou-se o predomínio da fração humina, seguida pelas frações dos ácidos húmicos e ácidos fúlvicos e atividade enzimática sendo mais elevada nos solo sob floresta primária. A sucessão floresta primária para seringais causa aumento da atividade microbiana e pouco altera a fertilidade do solo. Após o décimo oitavo ano de idade do seringal há recuperação de metade do teor de matéria orgânica do solo.

Orientador: Marli Teixeira de Almeida Minhoni
Resumo: O manejo agrícola altera, em muito, as características físicas, químicas e biológicas dos solos. A cultura e as condições climáticas, assim como o tipo de solo propriamente dito, afetam a decomposição da matéria orgânica do solo e, consequentemente, a biogeociclagem dos nutrientes. A matéria orgânica é uma característica importante em relação à fertilidade do solo, de modo que o impacto do uso do solo precisa ser avaliado principalmente em agroecossistemas. O conhecimento dos efeitos do uso da terra e das práticas agrícolas sobre a comunidade microbiana é de fundamental importância, em vista das importantes funções que os microorganismos desempenham no solo e que irão se refletir na produtividade agrícola. Neste sentido, uma avaliação da biomassa microbiana e de microorganismos do solo pode evidenciar diversas alterações no ecossistema do solo que estão associadas ao teor de argila e/ou sistemas de plantio. No presente estudo, caracterizou-se a camada superficial do perfil de solos sob plantio direto e plantio convencional em quatro fazendas no Brasil em relação a alguns de seus componentes microbiológicos. Para tanto, analisou-se, mensalmente, a respiração do solo, a biomassa microbiana e grupos de microorganismos. A avaliação da biomassa microbiana foi feita através da técnica da fumigação-incubação (FI), utilizando-se a Equação: [(C-CO2 liberado pelo solo fumigado, no período de 0-10 dias de incubação) - (C-CO2 liberado pelo solo não-fumigado, ao longo de 10-20 dias de incubação)]/0,45. Os cálculos indicaram um conteúdo de carbono da biomassa microbiana significativamente maior nos solos sob sistema de plantio direto em relação àqueles sob plantio convencional, na camada amostrada (0-10 cm de profundidade). Quantidades significativamente maiores ...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The crop management changes greatly the physical, chemical and biological soil properties. Furthermore, the crop and soil types, and the climatic conditions would affect on soil organic matter decomposition and on nutrients biogeociclying. Soil organic matter is a important characteristic in relationship soil fertility. The knowledge about effects on soil using and agriculture practices on soil microbial communities is very important, due to the function that microorganisms have in soil and it was going to in soil fertility. In this sense, evaluation of the soil microbial biomass and micro-organisms greatly aids predictions several changes in the soil ecosystems are associated with reduced tillage as compared with conventional tillage. Surface soils from long-term no-till and conventional tillage plots at four Brazil farms were characterised for microbial components. Soil respiration, microbial biomass carbon and counts of microorganisms were measured at intervals monthly. The evaluation of microbial biomass carbon was done by fumigation-incubation technique (FI). For calculating the soil microbial biomass carbon, the equation used was: Equation = [(CO2-C evolved by fumigated soil, 0-10 days) - (CO2-C evolved by unfumigated soil, 10-20 days)]/0,45. Significantly greater amounts of CO2-C were released from no-till than from conventional tilled soils. qCO2 values were not significantly different between tillage systems. This observation confirms that the tillage affected biological activity in those soils, further that qCO2 values didn't have significantily different which two tillage systems, in studied soils. Number both fungi and bacteria were assayed by Most Probable Number (MPN) by the agar drop counting technique and the microorganisms groups were calculated using by traditional Most Probable Number (MPN) method...(Complete abstract, click electronic access below)
Doutor

A demanda por informações relativas à ciclagem de nutrientes no solo sob sistema plantio direto (SPD) motivou o estudo das variações da biomassa microbiana do solo (BMS) em áreas com diferentes texturas submetidas há longo tempo a esse tipo de manejo. Na região de Campos Gerais, Tibagi (PR) é adotada a seqüência de culturas soja e milho no verão, seguidos de trigo e aveia preta no inverno há mais de 20 anos. O objetivo foi monitorar as variações do C e N-microbianos durante um ciclo de rotação em quatro áreas, sendo três com histórico de 12 anos sob SPD, com textura muito argilosa (PD12-TmuA), argilosa (PD12-TA), e média argilosa (PD12-TmeA), e uma com histórico de 22 anos sob SPD com textura argilosa (PD22-TA). No período de 18 meses foram realizadas nove amostragens de solo em quatro camadas (0-2,5; 2,5-5; 5-10; 10-20 cm). Foram avaliadas também alguns parâmetros das raízes do milho e da soja no PD22-TA visando determinar a influência de culturas distintas (plantas C4 e C3) sobre a concentração de BM no perfil do solo. A diferença de dez anos no tempo de adoção do SPD determinou aumento do C-microbiano no PD22-TA sobre o PD12-TA nas camadas mais profundas do solo. O PD22-TA também apresentou em média 30,8 kg Nmic.ha -1 mais BM-N que o PD12-TA na camada 0-20cm, com menor amplitude de variação. As diferenças na textura dos solos há 12 anos sob SPD resultou em maiores médias de C e N-microbiano na camada 0-20 cm na área mais argilosa (PD12-TmuA), exceto nos 20 dias após o plantio do trigo (jun/01). O PD12-TA e o PD12-TmeA não apresentaram diferenças significativas nas quantidades de C-microbiano somente na camada de 0-5cm. O C-microbiano apresentou correlação com o N-NH4 + e o N-NO3 - que o N-microbiano, independente da textura, do tempo de adoção SPD e da seqüência de culturas. O sistema radicular fasciculado do milho totalizou 1324 kg C ha -1 e 58 kg N ha -1 , com maior densidade por comprimento e por matéria seca de raízes ativas e raízes em vias de decomposição na camada superficial. O sistema radicular pivotante da soja (392 kg C ha -1 e 21 kg N ha -1 ) teve contribuição maior de raízes finas e densidade por comprimento do que o milho. O efeito das raízes do milho sobre o C-microbiano atingiu camadas mais profundas do que as raízes da soja. O N-microbiano foi estimulado pela concentração das raízes finas ativas e pelas raízes em decomposição ou de forma indefinida, possivelmente devido à maior concentração de C e N de fácil assimilação liberado ao solo. Concluiu-se que em função do tempo de adoção do SPD o C-microbiano aumenta em profundidade e o N-microbiano apresenta menor variação na camada 0-20 cm. A quantidade de C e N-microbiano é influenciada pela textura do solo. Entretanto, solos de classes textural próximas e sob SPD podem apresentar quantidades iguais de C–microbiano na camada 0-5 cm durante o sistema de produção.
The demand for information about the nutrient cycling in soils under no-tillage motivated the study about soil microbial biomass (SMB) variations in different texture soils submitted for a long period to this kind of management system. The usual sequence of crops adopted for more than 20 years in Campos Gerais, Tibagi (PR) is soybean/corn during the summer and wheat/oats during the winter. The objective was to keep track of the microbial-C and N variations during a crop rotation cycle in four areas: three of them have been cultivated for 12 years under the no-tillage system, with a clay (PD12-TmuA), a sandy clay (PD12-TA), and a sandy clay loam (PD12-TmeA) texture, and a fourth, 22 years under the no-tillage system with a sandy clay loam textural class (PD22-TA). Nine soil samplings were performed during a period of 18 months, each time collecting four soil layers (0-2,5; 2,5-5; 5-10; 10-20 cm). Several corn and soybean root parameters were also evaluated in PD22-TA to determine the influence of diverse crops (C4 and C3 plants) on the microbial biomass concentration in the soil profile. The ten-year difference in no-tillage system adoption caused and increase of microbial-C in PD22-TA in relation to PD12-TA in the deeper soil layers. The PD22-TA also showed, on average, 30,8 kg Nmic.ha -1 more microbial-N than the PD12-TA in the 0-20 cm, with a narrower range of variation. The divergence in texture among the 12-year no-till sites resulted in higher microbial-C and N means in the 0-20 cm soil layer, except for 20 days after the wheat sowing. PD12-TA and PD12-TmeA did not show significant differences in the microbial-C amounts only for the 0-5cm layer. Microbial-C was more positively correlated with N-NH4 + and N-NO3 - than microbial-N, independently of soil texture, time since no-till adoption and crop sequence. The corn root system totaled 1324 kg C ha -1 and 58 kg N ha -1 in the upper soil layer, with higher density per length and per active root dry mass, and more roots in decomposition. The soybean root system (392 kg C ha -1 and 21 kg N ha -1 ) contributed more with fine roots and density per length than the corn. The effect of the corn root system on microbial-C reached deeper soil layers than the soybean roots. Microbial-N was stimulated by fine and active root concentration and by roots in decomposition phase, probably due to higher labile C and N concentration released to the soil. It was concluded that the microbial-C increased in depth along the period of no-till adoption, while the microbial-N showed less variation in the 0-20 cm soil layer. Both microbial-C and N are influenced by soil texture, although similar textural classes under no-till can maintain similar microbial-C amounts in the 0-5 cm soil layer during the crop production system.

Magistrantūros studijų baigiamajame darbe pateikiami dirvožemio organinės anglies, humuso, C/N santykio, mikroorganizmų biomasės anglies, dirvožemio kvėpavimo tyrimų duomenys, įvertinant skirtingus žemės dirbimo būdus skirtingais dirvožemio gylio sluoksniais. Lyginami 2009 ir 2013 metų atliktų tyrimų duomenys. Darbo objektas – giliau karbonatingas giliau glėjiškas rudžemis, kuriame 2009 ir 2013 metais buvo žirnių (Pisum sativum L.) pasėlis, kur tirta skirtingo žemės dirbimo įtaka dirvožemio organinės anglies ir mikroorganizmų biomasės anglies sankaupoms. Darbo metodai: eksperimentai įrengti keturiais pakartojimais. Pradinių laukelių plotas – 126 m2, apskaitinių – 84 m2. Variantai pakartojimų blokuose išdėstyti rendomizuotai. Dirvožemio kvėpavimas ir mikroorganizmų biomasės sankaupos įvertintos 2009 ir 2013 m. birželio mėn. žirnių pasėliuose. Dirvožemio organinės anglies ir mikroorganizmų biomasės sankaupoms vertinti viršutinio ariamojo Ap (0-10 cm) horizonto jungtiniai ėminiai 3 pakartojimais buvo surinkti su 2-4 cm skersmens dirvožemio grąžtu. Eksperimento variantai: tradicinis žemės dirbimas, supaprastintas žemės dirbimas, tiesioginė sėja, ekologinė žemdirbystės sistema, kur taikytas tradicinis žemės dirbimas. Darbo rezultatai. Skirtingi žemės dirbimo būdai ir ekologinės žemdirbystės sistema, taikant tradicinį žemės dirbimo būdą, turėjo įtakos dirvožemio organinės anglies, humuso, C/N santykio, kvėpavimo ir mikroorganizmų biomasės anglies sankaupoms. Didžiausios org. C... [toliau žr. visą tekstą]
The master work presents the results on soil organic carbon, humus, C/N ration, microbial biomass carbon, soil respiration in soil with different soil tillage systems in two soil depths (0-10; 10-20 cm). Results were obtained in 2009 and 2013 and presented. Object of the research – The Endocalcari-Endohypogleyic Cambisol, where in 2009 and 2013 pea crops (Pisum sativum L.) have been growing. Soil tillage impact on soil organic carbon and microbial biomass carbon pools has been investigated. Method of the research – experiments was installed in four replications. Research area – 126 m2, research plot – 84 m2. Variants in blocks were rendomized. Soil respiration and microbial biomass pools were investigated in 2009 and 2013 in June in pea crops. Experiment variants were as followed: conventional tillage, reduced tillage, no tillage and ecological soil management with conventional tillage. Research results. Different soil tillage systems and ecological soil management system with conventional tillage had impact on soil organic carbon, humus, C/N ration, soil respiration and microbial biomass carbon pools. The highest org. C, humus, microbial biomass carbon concentrations and soil respiration intensity have been found in ecological soil management system. The fertilization with siderate crop may effect it mainly. The lower soil tillage intensity influenced the increase in org. C, humus concentration in 0-10 cm soil depth. In other hand, also along with lower tillage intensity... [to full text]

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The identification of soil quality indicators that demonstrate the alterations occurred in areas under organic management is important to determine the sustainability of this kind of cultivation. The soil microbial biomass and activity have been considered as important indicators of soil quality, especially when different management systems are employed in agroecosystems. In this context, the aim of this work was to evaluate management systems (organic and conventional) of the sugar cane over the soil quality, analyzing the chemical attributes as organic matter, pH, potential acidity, aluminium, magnesium, calcium, potassium, cation-exchange capacity, (CEC), sum of bases (SB), and percent base saturation (%BS), as well as the microbiological attributes as number of fungi and bacteria, microbial biomass carbon (MBC), basal respiration (BR) and metabolic quotient (MQ). The soil analyses were taken in the period comprised between May/2009 and September/2010. Among the chemical parameters that most showed the alterations in soil caused by the management are pH, magnesium concentration, potential acidity, SB and %BS. Higher values obtained with these two last parameters in the organic systems with addition of compost and limestone (SOCA) or compost and corrective, especially, indicate soil fertility. There was no significant difference among the treatments concerning MBC probably because it is an area where only recently the experiments were established. An influence of the sampling period was observed, with high values in the higher rainfall period. Higher values of BR were detected in the organic systems, especially in May and August/2009, which was coincident with the higher rainfall period and temperature. Although no significant difference was verified, the higher values of MQ were verified in the conventional system. Concerning the number of fungi and bacteria, the microbial community seemed to respond better to the climate/rhizosphere than the treatments involving the different management systems. Among the parameters studied, the BR was the most effective parameter to detect changes that occur in the soil due to the management system, showing that the organic system altered the soil quality, which reflected in the microbial activity.
A identificação de indicadores de qualidade de solo que demonstrem as alterações ocorridas em áreas agrícolas é importante para determinar a sustentabilidade do sistema de cultivo. A biomassa e a atividade microbiana do solo têm sido apontadas como importantes indicadores de qualidade do solo, especialmente quando se avalia o efeito de diferentes sistemas de manejo em agroecossistemas. Neste contexto, o objetivo deste trabalho foi avaliar o efeito de sistemas de manejo (orgânico e convencional) da cana-de-açúcar sobre a qualidade do solo, analisando-se os atributos químicos como matéria orgânica, pH, acidez potencial, alumínio, magnésio, cálcio, potássio, capacidade de troca catiônica (CTC), soma de bases (SB), porcentagem por saturação de bases, (V %); e microbiológicos como número de bactérias e fungos, carbono da biomassa microbiana (CBM), respiração basal (RB) e quociente metabólico (qCO2). As análises de solo foram realizadas no período compreendido entre Maio/2009 a Setembro/2010. Entre os parâmetros químicos que mais mostraram as alterações no solo provocadas pelo manejo estão o pH, teor de magnésio, acidez potencial, SB e V%. Valores mais elevados obtidos com estes dois últimos parâmetros nos sistemas orgânicos com adição de composto e calcário (SOCA) ou composto e corretivo (SOCO), especialmente, indicam fertilidade do solo. Não houve diferença significativa entre os tratamentos quanto ao CBM provavelmente por ser área recém implantada. Houve influência da época de amostragem, observando-se valores mais altos na época de maior pluviosidade. Valores superiores de RB foram detectados nos sistemas orgânicos, especialmente em Maio e Agosto/2009, coincidente com períodos de maior pluviosidade e temperatura. Embora não tenha sido observada diferença significativa, os maiores valores de qCO2 foram verificados no sistema convencional. Em termos de contagem de fungos e bactérias, a biota microbiana do solo pareceu responder mais ao clima/rizosfera que aos tratamentos envolvendo os sistemas orgânico e convencional. Dentre os parâmetros estudados e no período de tempo analisado, a respiração basal foi o parâmetro mais efetivo para detectar mudanças que ocorreram no solo devido ao sistema de manejo, mostrando que o sistema orgânico alterou a qualidade do solo, refletindo na atividade microbiana.

Woody plant invasion of grasslands is prevalent worldwide, but the biogeochemical consequences of this vegetation shift remain largely unquantified. In the Rio Grande Plains, TX, grasslands and savannas dominated by C4 grasses have undergone succession over the past century to subtropical thorn woodlands dominated by C3 trees/shrubs. To elucidate mechanisms of soil organic carbon (SOC) and soil total N (STN) storage and dynamics in this ecosystem, I measured the mass and isotopic composition (δ13C, δ15N) of C and N in whole-soil and soil size/density fractions in chronosequences consisting of remnant grasslands (Time 0) and woody plant stands ranging in age from 10-130 years. Rates of SOC and STN storage averaged 10-30 g C m-2yr-1 and 1-3 g N m-2yr-1, respectively. These accumulation rates increased soil C and N pools 80-200% following woody encroachment. Soil microbial biomass (SMB-C) also increased after woody invasion. Decreasing Cmic/C org and higher qCO2 in woodlands relative to grasslands suggests that woody litter is of poorer quality than grassland litter. Greater SOC and STN following woody invasion may also be due to increased protection of organic matter by stable soil structure. Soil aggregation increased following woody encroachment; however, most of the C and N accumulated in free particulate organic matter (POM) fractions not protected within aggregates. Mean residence times (MRTs) of soil fractions were calculated based on changes in their δ13C with time after woody encroachment. Free POM had the shortest average MRTs (30 years) and silt+clay the longest (360 years). Fine POM had MRTs of about 60 years, reflecting protection by location within aggregates. δ15N values of soil fractions were positively correlated with their MRTs, suggesting that higher δ15N values reflect an increased degree of humification. Increases in SOC and STN are probably being sustained by greater inputs, slower turnover of POM (some biochemical recalcitrance), and protection of organic matter in aggregates and association with silt and clay. Grassland-to-woodland conversion during the past century has been geographically extensive in grassland ecosystems worldwide, suggesting that changes in soil C and N dynamics and storage documented here could have significance for global C and N cycles.

The ecological significance of coarse woody debris (CWD) is usually highlighted in forests where CWD constitutes much of an ecosystem's carbon (C) source and stores. However, a unique addition of CWD is occurring in semi-deserts for which there is no ecological analog. To stem catastrophic wildfires and create firebreaks, whole Juniperus osteosperma (Torr.) and Pinus edulis (Engelm.) trees are being mechanically shredded into CWD fragments and deposited on soils previously exposed to decades of tree-induced changes that encourage "tree islands of fertility." To investigate consequences of CWD on C and nitrogen (N) cycling, we evaluated microbial metabolic activity and N transformation rates in Juniperus and Pinus surface and subsurface soils that were either shredded or left untreated. We sampled three categories of tree cover on over 40 tree cover encroachment sites. Tree cover categories (LOW = 0-15%, MID ≥ 15-45%, HIGH ≥ 45%) were used to indicate tree island development at time of treatment. In conjunction with our microbial measurements, we evaluated the frequency of three exotic grasses, and thirty-five native perennial grasses to identify links between belowground and aboveground processes. The addition of CWD increased microbial biomass by almost two-fold and increased microbial efficiency, measured as the microbial quotient, at LOW Juniperus cover. C mineralization was enhanced by CWD only in Pinus soils at the edge of tree canopies. The addition of CWD had little impact on microbial activity in subsurface soils. CWD enhanced the availability of dissolved organic C (DOC) and phosphorus (P) but tended to decrease the overall quality of labile DOC, measured as the ratio of soil microbial biomass to DOC. This suggested that the increase in DOC alone or other environmental factors novel to CWD additions lead to the increase in biomass and efficiency. P concentrations were consistently higher following CWD additions for all encroachment levels. The CWD additions decreased N mineralization and nitrification in Juniperus and Pinus soils at LOW and MID tree cover but only in surface soils, suggesting that less inorganic N was available to establishing or residual plants. The frequency of native perennial grasses, especially Elymus elymoides (Raf.), was at least 65% higher under CWD additions for all categories of tree cover, while the frequencies of exotic annual and perennial grasses were not impacted by CWD. The frequency of all perennial grasses ranged from 10-27%. Our results suggest that CWD enhanced microbial activity even when the quality of C substrates declined requiring microbes to immobilize more N. The reduction in inorganic N may promote the establishment and growth of native perennial grasses. Ultimately, the addition of CWD improved soil conditions for microbes in tree islands of fertility.

A mudança de uso da terra no Cerrado acarreta em alterações na dinâmica da matéria orgânica do solo (MOS). Práticas de manejo com revolvimento das camadas de solo aceleram a decomposição da MOS, favorecendo as emissões de gases do efeito estufa do solo para atmosfera. Dessa forma, o objetivo desse trabalho foi avaliar as mudanças na dinâmica da MOS de um Neossolo Quartzarênico submetido a diferentes usos e sistemas de manejo, utilizando como referência o sistema nativo (Cerrado). O presente estudo foi realizado no município de Comodoro - MT (13º50\'00\" a 13º50\'03\" S e 59º37\'18\" O). Foi empregado o delineamento experimental inteiramente casualizado com sete áreas de estudo. As coletas foram realizadas em julho de 2005 e fevereiro de 2006 e as áreas amostradas foram: Cerrado nativo (CER); pastagem (CAP22); plantio convencional com a cultura da soja (CS1), sucessão de culturas arroz-soja (CAS3) e sucessão arroz-soja-sorgo ou milheto (CAS/Sor3 e CAS/M3); e plantio direto (CAP13S/M5). Foram estudadas as seguintes variáveis: atributos físicos e químicos do solo, estoques de carbono (C) e nitrogênio (N) do solo, teores de C e N nas frações granulométricas da MOS, quantidades de N inorgânico, C e N microbiano do solo, quociente metabólico (qCO2) e fluxos de gases do solo (CO2, N2O e CH4). Os resultados deste estudo indicaram que os sistemas com plantio convencional e plantio direto avaliados apresentaram melhoria nos atributos físicos e químicos do solo em relação a pastagem (CAP22), com menor compactação do solo e aumento na disponibilidade de fósforo, cálcio e magnésio. Foram obtidos maiores estoques de C e N em CAS/Sor3 e CAS/M3, áreas com maiores teores de argila. A área CAP13S/M5 também mostrou maiores teores de argila, porém baixos estoques de C e N, resultado atribuído ao uso da terra por treze anos com pastagem sem reforma e ao pouco tempo de implantação do sistema plantio direto. Analisando as frações granulométricas da MOS verificou-se maiores teores de C e N na fração menor que 50 \'mü\'m. As maiores quantidades de N inorgânico em relação ao CER foram observados na área CAS/M3, e com exceção desta área, a forma predominante de N inorgânico foi o amônio. Foram obtidas maiores quantidades de C e N microbiano na época úmida, quando todas as áreas estavam com cobertura vegetal. Entre as áreas de estudo, as maiores quantidades de C e N microbiano foram obtidos em CAP22. Os fluxos de C-CO2, com exceção da área CAS/Sor3, foram maiores na época úmida, enquanto que os fluxos de N-N2O e C-CH4 foram semelhantes entre as épocas de estudo. Os fluxos de gases em C equivalente não apresentaram diferenças significativas entre as áreas de estudo devido ao alto desvio padrão verificado para cada gás. A mudança de uso da terra promove alterações na dinâmica da MOS, porém neste estudo não foi possível distinguir qual o melhor sistema de uso para o Neossolo Quartzarênico devido ao pouco tempo de implantação dos sistemas plantio convencional e plantio direto, e a degradação da pastagem (apesar do maior tempo de implantação)
Land-use changes of Brazilian savanna (Cerrado) result in alterations of the soil organic matter (SOM). Managements practices with tillage accelerate the SOM decomposition, enhancing greenhouse gases emissions from the soil to the atmosphere. Therefore, the objective of this work was to evaluate the changes in the SOM dynamics of a Typic Quartzipisamment submitted to different uses and managements systems, using as reference the native system (Cerrado). The present study was conducted in areas located at Comodoro (Mato Grosso state, Brazil) (from 13º50\'00\" till 13º50\'03\" S and 59º37\'18\" W). At each site, samples were taken randomly within seven areas. Sampling activities were performed in July 2005 and February 2006 and the sample sites consist of an area of \"Cerrado\" (CER); pasture (CAP22); conventional tillage with soybean (CS1), rice-soybean succession (CAS3) and rice-soybean-sorghum or millet (CAS/Sor3 and CAS/M3) successions; and a field with no-tillage system (CAP13S/M5). Studied variables were: physical and chemical attributes, C and N stocks, isotopic composition of 13C/12C and 15N/14N, C and N content in the SOM fractions, quantity of inorganic N, microbial C and N biomass, metabolic quotient (qCO2), and the soil gases fluxes (CO2, N2O and CH4). The results of this study showed that all evaluated fields under conventional or no-tillage systems result in physical and chemical attribute improvement in relation to the pasture (CAP22), with soil compaction decrease, pH increase and improvement of the availability in phosphorus, calcium and magnesium. The C and N stocks were higher in areas CAS/Sor3 and CAS/M3, corresponding to the highest clay content. The area CAP13S/M5 showed similar clay content, but smaller C and N stocks, this result was attributed to the land-use: thirteen years as pastures without reform and also the short time of no-tillage implantation. Analyzing the SOM fractions, it was verified higher C and N contents in the 50 \'mü\'m fraction. The higher quantities of inorganic N in relation to the CER were found in area CAS/M3, and with exception of this area, ammonium was the predominant form of inorganic N. Higher quantities of the microbial C and N were obtained during the wet season, when all areas presented a cover crop. Among areas, the higher quantities of microbial C and N were obtained in CAP22. The fluxes of C-CO2, excepting area CAS/Sor3, were higher during the wet season, while the fluxes of N-N2O and C-CH4 were similar between seasons studied, because high standard deviations were calculated for each gas. The land use promoted alterations in SOM dynamic, however it was not possible to differentiate the best land use for this Typic Quartzipisamment, mainly due to the short time of no-tillage implantation, and the degradation of the pasture (although of the implantation time was higher)

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Among the parameters used by the scientific community, the biomass evaluation is the most precise one in terms of presenting the biological components of the soil. Intending to evaluate the potential of the legumes Campo Grande Stylo, calopo (Calopogonium mucunoides) and pigeon pea regarding the recovery of damaged soil, sixteen plats of these legumes were planted in latin square form for later microbial biomass analysis. The microbial biomass was analyzed according to the Vance et. (1987) principles. No significant differences were found compared to the fallow, although circumstances like the lack of precipitation, the time of the year and the production of dry matter affected the microbial biomass development. The studied legumes that presented the largest microbial biomass production were the Campo Grande Stylo and the calopo (Calopogonium mucunoides), showing a trend of improvement compared to the fallow. Despite the stress factors, the microbial biomass showed a trend of improvement on the plats where the legumes were seeded, and it can be considered a prior parameter of agrisystem changes.
Dentre os parâmetros utilizados pela comunidade científica, o que apresenta maior sensibilidade na caracterização dos componentes biológicos do solo é a avaliação de biomassa microbiana (BMS). Com o objetivo de avaliar o potencial das leguminosas Calopogônio, Estilosantes e feijão Guandu na recuperação dos solos degradados e na melhoria da biomassa microbiana, foi realizado o plantio das leguminosas e posterior análise da biomassa microbiana em dezesseis canteiros distribuídos em um quadrado latino. A biomassa microbiana foi analisada conforme os princípios de Vance et. (1987). Não foram encontradas diferenças significativas em relação ao pousio, porém fatores como a baixa pluviosidade, época de plantio e produção de massa seca influenciaram o desenvolvimento da BMS. As leguminosas estudadas que apresentaram maior produção de BMS foram o Estilosantes e o Calopogônio, evidenciando uma tendência de aumento em relação ao pousio. Mesmo com fatores de estresse, a biomassa microbiana nos canteiros com as leguminosas evidenciou um potencial de aumento, podendo ser considerado um parâmetro que antecede alterações no agrosistema.

The Southern Appalachian hardwood forests contain a wide diversity of flora and fauna. Understanding processes that affect nutrient availability in these forests is essential for sound forest management. Three interconnected research projects regarding soil resource heterogeneity were designed to increase our understanding of this ecosystem. The objective of these projects were as follows: 1) to examine and quantify the role of decaying stumps in regards to total carbon (C) and nitrogen (N) pools and fine-root dynamics, 2) compare and contrast the use of ground-penetrating radar (GPR) vs. a soil auger for estimating soil depth and site quality and 3) to evaluate how eastern red-backed salamanders (Plethodon cinereus) affect N-availability. For the stump study, results show that decomposing stumps occupy approximately 1.2% of the total soil volume and constitute 4% and 10% of total soil N and C pools. Significant differences in N (p = 0.0114), C (p = 0.0172), microbial biomass C (p = 0.0004), potentially mineralizable N (p = 0.0042), and extractable NH4+ (p = 0.0312) concentrations were observed when compared to mineral soil horizons. In particular, potentially mineralizable N was 2.5 times greater in stump soil than the A-horizon (103 vs. 39 mg kg-1), 2.7 times greater for extractable NH4+ (16 vs. 6 mg kg-1) and almost 4 times greater for MBC (1528 vs. 397 mg kg-1). These measured properties suggest higher N-availability, organic matter turnover and N uptake in stump soil versus the bulk soil. 19% of the total fine root length and 14% of fine root surface area also occurred in the stump soil. The increased fine root length suggests higher concentrations of labile nutrient in the stumps since roots often proliferate in areas with higher nutrient availability. Significant differences occurred in N and C concentrations between all four decay classes and the A-horizon, which validated the use of this system and the need to calculate weighted averages based on the frequency and soil volume influenced by each decay class. In the GPR Study, depth estimations were shallower using a soil auger compared to estimates obtained using GPR across all plots (p = 0.0002; Figure 3.4). On a soil volume basis, this was equivalent to about 3500 m3 of soil per hectare unaccounted for using traditional methods. In regards to using soil depth as a predictor for site quality, no significant relationships were observed with soil depth estimations obtained from the auger (Table 3.3). On the other hand, depth measurements from GPR explained significant amounts of variation across all sites and by physiographic region. Across all sites, soil depth estimates from GPR explained 45.5% of the residual variation (p = 0.001; Table 3.3). When the data were stratified by physiographic region, a higher amount of variation was explained by the regression equations; 85% for the Cumberland Plateau (p = 0.009), 86.7% for the Allegheny Plateau (0.007) and 66.7% for the Ridge and Valley (p = 0.013), respectively (Table 4.2). Results from this study demonstrate how inaccurate current methods can be for estimating soil depth rocky forests soils. Furthermore, depth estimations from GPR can be used to increase the accuracy of site quality in the southern Appalachians. In the salamander study, no significant salamander density treatment or treatment by time effects were observed over the entire study period (p < 0.05). However, when the data were separated by individual sampling periods a few significant treatment by time interactions occurred: 1) during August 2006 for available NH4+ under the forest floor (i.e. horizontal cation membranes; p = 0.001), 2) August and 3) September 2006 for available NH4+ in the A-horizon (p = 0.026), and 4) May 2007 for available NO3- under the forest floor (p = 0.011). As a result of these trends, an index of cumulative N-availability (i.e. NH4+ and NO3-) under the forest floor and in the A-horizon was examined through the entire study period. Cumulative N-availability under the forest floor was consistently higher in the low- and medium-density salamander treatments compared to the high-density treatment. For cumulative N-availability in the A-horizon, a gradient of high to low N-availability existed as salamander density increased. Factors such as a prolonged drought in 2007 may have affected our ability to accurately assess the effects of salamanders on N-availability. We concluded that higher salamander densities do not increase N-availability. Implementing methodologies that accurately account for soil nutrient pools such as stump soil, physical properties such as depth and fauna such as salamanders, increase our understanding of factors that regulate site productivity in these ecosystems. As a result, landscape-level and stand-level management decisions can be conducted more effectively.
Ph. D.

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wastewater use in agricultural soils has been adapted as an important pratice for agriculture. Due to the reduction of the availability of the quality of water resources is becoming increasingly important to add value to the use of water. The swine wastewater is rich in organic matter, composed of various elements of chemical origin, physical and biological. Its addition in soil and water resources without previous studies and knowledge of its components, can cause changes in the soil, contamination of surface and groundwater, biology changes in these environments, as well as the contribution and accumulation of groups of microorganisms in the environment, including pathogens. Most studies on swine wastewater, mainly in Brazil, are restricted to its physical and chemical components, evaluating its impact directly on the ground, water bodies or in plant productivity. Few studies focus on the microbial composition of this type of waste and especially on the risk of environmental contamination by pathogenic microorganisms or even on the impact of this element in the soil microbial community. Thus these animal manure may have an important role as initiators of infectious diseases in animals and humans. Thus, this thesis consists of two papers. In the first article, a study was done to check the bacterial composition present in swine wastewater, and to verify the possibility of eliminating these microorganisms through the main anaerobic treatment systems used in Brazil. It was evaluated in particular pathogenic microorganisms of gastrointestinal origin of the pigs and microbial environmental markers. The wastewater samples were taken from pig farms that use bio-manure storage tanks and digesters as treatment methods for the waste. The results clearly showed the presence of biomarkers and pathogens in swine wastewater. Despite the possibility of decrease of certain microbial groups throughout the stages of the treatment process, no elimination of pathogens in either treatment systems. Thus, demonstrates the possibility of the spread of pathogens and microorganisms in the environment. In the second paper, the objective was to evaluate the effect of application of swine wastewater associated with mineral fertilizer in agriculture, after a long time of application of swine wastewater in the soil microbial community. Thus, samples were collected from soils after 18 production culture cycles, with the application of wastewater from pig farms and assessed the quantitative effects (basal respiration, microbial biomass and metabolic quotient) and qualitative (DGGE, biodiversity indices, correlation between the chemical conditions and soil microbial activity) in the soil microbial community. The results showed that the application of swine wastewater, especially after long time and in higher concentrations, can change the dynamics of soil microbial community, impacting the dump site. The results of these studies show the need for further studies to apply this type of waste in agricultural soils, in order to minimize the risk of environmental contamination and/ or spread of pathogens.
A utilização de água residuária em solos agrícolas vem sendo praticada como importante opção para agricultura. Devido à redução na disponibilidade de recursos hídricos, a reutilização de água residuária vem ganhando espaço na agricultura com a agregação de valor para o uso de água. A água residuária da suinocultura é rica em matéria orgânica, composta por diferentes elementos de origem química, física e biológica. Sua adição no solo e recursos hídricos, sem estudos prévios e conhecimento de seus componentes, pode provocar contaminação de águas superficiais e subterrâneas, alterações da biologia destes ambientes, bem como o aporte e acúmulo de grupos de microrganismos no ambiente, incluindo patógenos. A maior parte dos estudos sobre água residuária da suinocultura, principalmente no Brasil, se restringe aos seus componentes físicos e químicos, avaliando seu impacto diretamente sobre o solo, corpos d´agua ou na produtividade vegetal. Poucos estudos se concentram na composição microbiana deste tipo de resíduo e principalmente sobre o risco de contaminação ambiental por microrganismos patogênicos ou mesmo sobre o impacto deste elemento na comunidade microbiana do solo. Desta forma estes dejetos animais podem apresentar importante papel como iniciadores de doenças infecciosas em animais e seres humanos. Este trabalho de tese é constituído de dois artigos. No primeiro artigo, foi feito um estudo para verificar a composição bacteriana presente na água residuária da suinocultura, bem como verificar a possibilidade de eliminação destes microrganismos através dos principais sistemas de tratamento anaeróbicos utilizados no Brasil. Foram avaliados em especial os microrganismos patogênicos, de origem gastrointestinal dos suínos e bioindicadores microbianos. As amostras de água residuária utilizadas foram provenientes de granjas que utilizavam de sistemas anaeróbicos com esterqueiras e biodigestores no tratamento do resíduo. Os resultados obtidos mostraram claramente a presença de coliformes, mesofilos aeróbios, bolores e leveduras, enterococos e patógenos na água residuária da suinocultura. Apesar da possibilidade de decréscimo de determinados grupos microbianos ao longo das etapas dos processos de tratamento, não houve eliminação de patógenos em nenhum dos dois sistemas de tratamento, o que pode possibilitar a disseminação de microrganismos e patogenos no meio ambiente. No segundo artigo, o objetivo foi avaliar o efeito da aplicação da água residuária da suinocultura associada a adubação mineral, em área agrícola, após longo tempo de aplicação, na comunidade bacteriana do solo. Assim, foram coletadas amostras de solo com 18 ciclos de produção, com aplicação de água residuária de suinocultura e avaliados os efeitos quantitativos (respiração basal, biomassa microbiana e quociente metabólico) e qualitativos (DGGE) na comunidade bacteriana do solo. Os resultados mostraram que a aplicação de água residuária da suinocultura, principalmente após longo tempo e em concentrações maiores, pode alterar a dinâmica da comunidade bacteriana do solo, impactando no local de despejo. Os resultados dos artigos mostram a necessidade de maiores estudos para aplicação deste tipo de resíduo na agricultura, a fim de minimizar os riscos de contaminação ambiental e ou disseminação de patógenos.

Global change phenomena, such as forest disturbance and land-use change significantly affect elemental balances as well as the structure and function of terrestrial ecosystems. Inappropriate land management often causes nutrient losses and finally soil degradation and loss of soil functioning. Especially in tropical ecoregions, soil degradation by nutrient losses is widely abundant. Soil microorganisms are the proximate agents of many processes performed in soils and are regarded as sensitive bio-indicators. However, the incorporation of microbial responses to the definition of critical soil conditions is not intensively developed. In the present thesis, several data analyses of the relationships between ecosystem disturbance and land-use change (natural forest, pastures of different ages, secondary succession) and a diverse set of soil ecological characteristics in the tropical mountain rainforest region of southern Ecuador were compiled. In particular, it was tested whether soil microbial biomass and community functioning were sensitive to land-use change effects. Furthermore, an information-theoretic approach was applied to find the factors that regulate soil microbial biomass and community function. Finally, in a nutrient enrichment experiment the above- and belowground responses to N and P additions were examined. The tested research questions and results were linked to the theory of ecological stoichiometry in order to connect the research to a sound and unifying scientific basis. Soil and microbial stoichiometry were affected by both land-use change and soil depth. After forest disturbance, significant decreases of soil C:N:P ratios at the pastures were fol-lowed by increases during secondary succession. Microbial C:N ratios varied slightly in response to land-use change, whereas no fixed microbial C:P and N:P ratios were observed. Shifts in microbial community composition were associated with soil and microbial stoichiometry. Strong positive relationships between PLFA-markers 18:2n6,9c (saprotrophic fungi) and 20:4 (animals) and negative associations between 20:4 and microbial N:P point to land-use change affecting the structure of soil food webs. Significant deviations from global soil and microbial C:N:P ratios indicated a major force of land-use change to alter stoichiometric relationships and to structure biological systems. Data analysis reveals a strong impact of land-use change on soil microbial biomass, C-mineralization, gross-NH4-consumption and –production rates. According to the results of the IT-approach, combined models better describe effects of land-use change on soil microorganisms than single explanation models. Microbial resources and soil chemical environment were important pre-dictors for soil microbial biomass and community functioning. Little is known about the environmental drivers of the catalytic properties of EHEs (e.g., pH, nutrients) and their functional link to the structure of soil microbial communities. The activities of the six hydrolytic enzymes were tested. Microbial production of AP responded to the low P status of the sites by a higher investment in the acquisition of P compared to C. Three major drivers of enzyme activities were found to be significant for enzyme production: 1.) Microbial demand for P regulated the production of AP, provided that N and C were available. At the natural forest site the two-fold higher specific activity of AP pointed to a high microbial P-demand, whereas the production of AP was constrained by the availability of N and DOC after pasture abandonment. 2.) Microbial biomass that was controlled by pH and resource availability was the main driver for CBH, BG and NAG activities. 3.) Substrate induction due to increased litter inputs of herbaceous plant species seemed to regulate AG and XYL activities during secondary succession. The enzymes’ affinity to substrate, as a potentially critically enzyme kinetic parameter is understudied. The data analysis suggests that microbial communities adapted to environmental changes, demonstrated high flexibility of extracellular enzyme systems and selected for enzymes with higher catalytic efficiency compared with pure cultures. Under in situ conditions, enzyme-specific environmental drivers of the Km, e.g., the pH for XYL, the C:N ratio for AP, and the C availability for NAG were found. The data demonstrated that the higher substrate affinity of XYL and AP was associated with more abundance of Gram(-) bacteria. The catalytic efficiency of enzymes decomposing cellulose, hemicellulose, and starch positively correlated with the relative abundance of Gram(-) bacteria. The turnover rate of the tested substrates was three to four times faster at the young pasture site compared with the longterm pasture and secondary succession sites. Nutrient inputs by atmospheric deposition are known to affect terrestrial ecosystems. However, little is known about how N and P co-limited ecosystems respond to single nutrient enrichment. In this work the susceptibility of above- and belowground ecosystem compo-nents and of their linkages in an N and P co-limited pasture to N- and P-enrichment was assessed. It was tested if the plants´responses can be explained by the concept of serially linked nutrients introduced by Ågren (2004). In this concept, the control of the growth rate by one nutrient is assumed to depend on the control of a different cellular process by another nutrient. The responses of shoot and root biomass and C:N:P stoichiometry of the grass Setaria sphacelata (Schumach.) to moderate N, P, and N+P application over five years were investigated. In addition, the effects of nutrient enrichment on soil nutrient pools, on arbuscular mycorrhizal fungi (AMF) as well as on microbial biomass, activity, and community structure were tested. In order to evaluate the importance of different factors explaining microbial responses, a likelihood-based information-theoretic approach was applied. The application of N+P increased aboveground grass biomass. Root biomass was stimulated by P-treatment. Grass C:N:P stoichiometry responded by altering the P-uptake or by translocating P from shoot to root. In particular, root C:N and C:P stoichiometry decreased in P- and in N-treatment. Extractable fractions of soil C, N, and P were significantly affected by nutrient enrichment. P application increased the biomass of Gram-positive bacteria and the abundance of AMF, however, results of the IT-approach suggested indirect effects of nutrient enrichment on microbes. The responses of the N and P co-limited pasture to particular nutrient enrichment support the concept of serially linked nutrients. The present study provides evidence for the fundamental importance of P for controlling resource allocation of plants in responses to nutrient enrichment. Resource allocation of the grass rather than direct effects of nutrient additions drives changes in AMF, microbial biomass, community structure, and activity
Seit dem Übergang vom Holozän zum Anthropozän greift der Mensch immer stärker in globale und regionale Stoffkreisläufe ein. Durch die Zerstörung von Naturwäldern und Landnutzungswandel werden die Strukturen und die Funktionen der Ökosysteme stark verändert. Unangepasste Landnutzung führt zu Nährelementverlusten, die mittel- bis langfristige zur Bodendegradation und zur Reduktion von Bodenfunktionen führen. Solche Veränderungen sind insbesondere in den Tropen zu beobachten. Bodenmikroorganismen spielen in den Stoffkreisläufen eine zentrale Rolle. Zudem sind sie sensitive Bioindikatoren für den Zustand von Ökosystemen. Im Gegensatz dazu, werden die Bodenmikroorganismen noch nicht ausreichend für die Zustandsbewertung von Ökosystemen verwendet. In der vorliegenden Dissertation werden verschiedene Datenanalysen zu den Beziehungen von Landnutzungswandel (Naturwald, Weiden verschiedener Alter, sekundäre Sukzession) und den Eigenschaften der Bodenmikroorganismen in einer tropischen Bergregenwaldregion Süd-Ecuadors zusammengefasst. Ein besonderer Fokus lag darauf zu prüfen, ob die mikrobielle Biomasse und die Funktionen die von der mikrobiellen Gemeinschaft geleistet werden (z.B. Enzymaktivitäten) durch den Landnutzungswandel beeinflusst werden. Ein informations-theoretischer Ansatz wurde verwendet um verschiedene Erklärungsansätze der steuernden Faktoren vergleichend zu testen. Darüber hinaus wurden in einem Weidedüngungsexperiment die Reaktionen der ober- und der unterirdischen Ökosystemkomponenten auf die Anreicherung mit N und P getestet. Um die Ergebnisse auf eine breite wissenschaftliche Basis zu stellen wurde die Untersuchungen in den Kontext der Theorie die Ökologischen Stöchiometrie eingeordnet. Die C:N:P Stöchiometrie im Boden und in den Mikroorganismen veränderte sich durch den Landnutzungswandel und mit der Bodentiefe. Mit der Weideetablierung nahmen die C:N:P Verhältnisse im Boden deutlich ab, stiegen dann nach dem Verlassen der Weiden im Zuge der sekundären Sukzession wieder an. Das mikrobielle C:N Verhältnis variierte nur leicht, dagegen zeigten das C:P und N:P Verhältnis deutliche Veränderungen durch den Landnutzungswandel. Mit diesen Veränderungen in der Boden- und Organismenstöchiometrie waren auch Veränderungen in der Struktur der mikrobiellen Gemeinschaften verbunden. Deutliche positive Beziehungen existierten zwischen den saprotrophen Pilzen und den Protozoen. Die steigenden Mengen von Protozoen waren wiederrum mit sinkendem mikrobiellen N:P verbunden. Diese Muster weisen auf Veränderungen in den Bodennahrungsnetzten durch Landnutzungsänderungen hin. Sehr deutliche Abweichungen von globalen Mustern der C:N:P Stöchiometrie deuten darauf hin, dass der Landnutzungswandel signifikanten Einfluss auf die C:N:P Stöchiometrie ausübt. Der Landnutzungswandel beeinflusste auch die mikrobielle Biomasse, die Basalatmung, sowie die mikrobielle Aufnahme und Produktion von NH4-N im Boden. Dabei zeigten kombinierte Erklärungsansätze die adäquateren Beschreibungen der Muster. In den kombinierten Modellen zur Erklärung der mikrobiellen Biomasse und der mikrobiellen Leistungen überwogen Prädiktoren der mikrobiellen Ressourcen und der bodenchemischen Umwelt. Ein weiterer Schwerpunkt der Untersuchungen lag auf der Erfassung der Effekte des Land-nutzungswandels auf die Aktivität von extrazellulären Bodenenzymen. Bisher ist wenig darüber bekannt, welche Faktoren die katalytischen Eigenschaften steuern und beispielsweise, ob es Zusammenhänge zur mikrobiellen Gemeinschaftsstruktur gibt. Um diese Fragen näher zu beleuchten wurden sechs hydrolytische Enzyme basierend auf MUF-Substraten untersucht. Die mikrobielle Produktion von AP stand dabei in Zusammenhang mit dem niedrigen P-Status der untersuchten Böden. Das wurde besonders durch die hohe AP Produktion im Vergleich zu BG belegt. Im Allgemeinen konnten drei verschiedene Mechanismen festgestellt werden, die die Produktion der untersuchten EHEs vermutlich steuerten. 1.) Der P-Bedarf der Mikroorganismen regulierte die Produktion von AP, vorausgesetzt, dass ausreichend N und C zur Enzymsynthese zur Verfügung standen. 2.) Die Höhe der mikrobiellen Biomasse hat sich als wichtiger Faktor für die Produktion von CBH, BG und NAG gezeigt. Das deutet auf die konstitutive Produktion dieser Enzyme hin. 3.) Die substratinduzierte Produktion von Enzymen ist vermutlich entscheidend für die Aktivität von AG und XYL. Die Berücksichtigung der Enzymkinetiken, insbesondere der Michaelis-Menten-Konstante lieferte weitere Aufschlüsse über relevante Faktoren. Im Allgemeinen so scheint es, haben sich die mikrobiellen Gemeinschaften an die starken Umweltgradienten, die durch den Landnutzungswandel erzeugt worden angepasst. Im Vergleich zu den verfügbaren Daten aus Reinkulturen, wiesen die mikrobiellen Gemeinschaften der untersuchten Böden in der Regel eine deutlich höhere katalytische Effizienz auf. Auch für die Michaelis-Menten-Konstante sind die Faktoren enzymspezifisch. So ist für die Km von XYL der Boden-pH-Wert, für AP das C:N Verhältnis und für NAG die DOC-Menge entscheidend. Darüber hinaus haben sich deutliche Beziehungen zwischen der Menge an Gram(-)-Bakterien und der Substrataffinitäten von XYL und AP ergeben. Je höher die Gram(-)-Abundanz, desto höher war die Substrataffinität der Enzymsysteme. Gegenüber alter und degradierter Weiden, war der Umsatz der untersuchten Substrate im Oberboden der aktiv genutzten Weide drei- bis vierfach erhöht. In einem 5-jährigen Düngeexperiment in der Bergregenwaldregion der Anden Süd-Ecuadors wurden die Reaktionen des auf dieser Fläche N/P co-limitierten Grases (Setaria sphacelata), der Arbuskulären Mykorrhiza (AMF) sowie der Bodenmikroorganismen auf moderate N, P und N+P-Düngung untersucht. Die Zugabe von N+P erhöhte die oberirdische Biomasse (+61%) wohingegen die Wurzelbiomasse durch die Zugabe von P (+45%) anstieg. Die C:N:P Verhältnisse weisen auf veränderte P-Aufnahme oder Translokation von P in die Wurzeln hin. Im Besonderen verengte sich das Wurzel C:N and C:P in der P- und der N-Zugabe. Die aus dem Boden extrahierbaren C, N und P-Fraktionen wurden deutlich beeinflusst. Die Zugabe von P stimulierte die Biomasse Gram-(+)-Bakterien (+22%), die Abundanz der AMF (+46%) und die Brutto-N-Mineralisierung. Die Auswertungen deuten darauf hin, dass die Nährstoffanreicherung indirekt über die Veränderungen der Graswurzeln auf die Bodenorganismen wirkte. Die Ergebnisse bestätigen, dass N und P in den Reaktionen von co-limitierten Pflanzen eng miteinander verbunden sind. Vor allem aber steuert P grundlegend die Allokation von Ressourcen und wirkt damit auf andere Ökosystem-komponenten, z.B. auf die Struktur und Aktivität der Bodenmikroorganismen

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Land-use change and soil type can have significant impact on microbial communities of soil. The Pampa biome in recent decades has undergone severe changes in landscape due to landuse change, mainly for the introduction of exotic tree plantation and croplands. Different landuse in Pampa biome were evaluated to determine the effect on the structure of soil microbial communities. Furthermore, due to the presence of various soil types present in this biome, we investigated whether different soil type harbor different microbial communities. Soil samples were collected at two sites with different land-uses (native grassland, native forest, exotic tree plantation and cropland) and in a typical toposequence in Pampa biome formed by Paleudult, Albaqualf and alluvial soils. The structure of soil microbial community (archaeal and fungal) was evaluated by RISA and soil functional capabilities were measured by microbial biomass carbon and metabolic quotient. We detected different patterns in fungal and archaeal community driven by land-use change and soil type showing that both factors are significant drivers of microbial community structure and activity. Acacia and Eucalyptus afforestation presented the most dissimilar communities when compared with natural vegetation. Although differences in the communities were detected, the soils tested shared most of the taxonomic unities and only a proportion of the community suffers changes caused by human interference.
A mudança do uso da terra e o tipo de solo podem exercer impactos significantes sobre a comunidade microbiana do solo. O bioma Pampa Brasileiro, nas últimas décadas, tem sofrido severas mudanças na paisagem devido à mudança no uso da terra, principalmente pela introdução de plantações de árvores exóticas e pelos cultivos agrícolas. Diferentes usos do solo no bioma Pampa foram avaliados para determinar o efeito sobre a estrutura das comunidades microbianas do solo. Além disso, devido à presença de vários tipos de solo presentes neste bioma, foi investigado se diferentes tipos de solos abrigam diferentes comunidades microbianas. Amostras de solo foram coletadas em duas áreas com diferentes usos do solo (pastagem nativa, mata nativa, plantações de árvores exóticas e cultivo agrícola) e em uma topossequência típica no bioma Pampa formado por Argissolo, Planossolo e solos aluviais. A estrutura das comunidades microbianas do solo (arqueas e fungos) foi avaliada por RISA e capacidades funcionais do solo foram mensuradas através de carbono da biomassa microbiana e quociente metabólico. Diferentes padrões foram detectados nas comunidades de fungos e arqueas influenciados pela mudança no uso da terra e pelo tipo de solo, mostrando que ambos são importantes fatores da estrutura e atividade da comunidade microbiana. Florestamentos de acácia e eucalipto apresentaram as comunidades mais diferentes quando comparados com a vegetação natural. Embora diferenças nas comunidades foram detectadas, os diferentes usos e tipos de solos avaliados compartilham grande parte das unidades taxonômicas e mostram que apenas uma parte da comunidade sofre alterações causadas pela interferência humana.