Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-17T13:58:22Z No. of bitstreams: 1 Romero Falcao Bezerra de Vasconcelos.pdf: 1209446 bytes, checksum: 5d0e80152c5bbb339e575d66b8691373 (MD5) / Made available in DSpace on 2016-08-17T13:58:23Z (GMT). No. of bitstreams: 1 Romero Falcao Bezerra de Vasconcelos.pdf: 1209446 bytes, checksum: 5d0e80152c5bbb339e575d66b8691373 (MD5) Previous issue date: 2009-02-17 / The soils of the Coastal Plains cultivated with sugarcane for a long period of time under different management systems may make changes in physical and chemical properties and the state of soil aggregation. Considering the above, the objective of this study was to evaluate the effects of different management systems with sugarcane on the chemical and physical properties of a dystrophic cohesive Yellow Latosol of coastal tablelands of Alagoas. Plots were selected in areas of production in the growing of sugarcane, and the object of experimental research three areas, representative of three management systems adopted by sugarcane production unit, namely: a cultivated area under irrigation management system (SMI), an area under the management system of fertirrigation with vinasse (SMV) and area under a management system with application of vinasse + filter tart (SMVT). These management systems were compared and on the witness pattern represented by native forest (NF). To assess the physical and chemical properties and aggregation state of the soil, the soil samples were collected at random in the areas subject to different management systems, in the depths of 0- 0,20; 0,20-0,40 and 0,40-0,60 m, being withdrawn at a point between the lines of sugarcane. The results were submitted to analysis of variance and the averages compared by Tukey test to 5% significance. Study of simple correlations were performed between some variables measures. The results showed that the different management systems promoted investigated changes in physical and chemical properties and the state of soil aggregation. The parameters of consistency of the soil tended to increase the humidity in their values with the increase of total organic carbon (TOC) of soil, promoted by the addition of waste from sugar cane. The studies of simple correlations between the total organic carbon (TOC) and the rates of stability of aggregate investigated, showed significant (p<0,01) correlation and positive. The management systems that received the addition of waste from sugarcane showed less deterioration in physical and chemical properties of soil in the soil under native forest (NF). / Os solos dos tabuleiros costeiros cultivados com cana-de-açúcar, durante longo período de tempo, sob diferentes sistemas de manejo, podem apresentar alterações nas propriedades físicas e químicas e no estado de agregação. O objetivo do trabalho foi avaliar os efeitos de diferentes sistemas de manejo com cana-de-açúcar sobre as propriedades físicas e químicas de um Latossolo Amarelo Distrocoeso dos tabuleiros costeiros de Alagoas. Foram selecionadas áreas em talhões de produção com a cultura da cana-de-açucar, sendo objeto de pesquisa experimental três áreas, representativas de três sistemas de manejo adotados pela unidade sucroalcooleira, a saber: uma área cultivada sob sistema de manejo irrigado (SMI), uma área sob sistema de manejo de fertirrigação com vinhaça (SMV) e uma área sob sistema de manejo com aplicação de vinhaça + torta de filtro (SMVT). Esses sistemas de manejo foram comparados entre si e em relação a uma testemunha padrão, representada por uma mata nativa (MN). Para avaliar as propriedades físicas e químicas e o estado de agregação do solo, amostras de solo foram coletadas ao acaso, nas áreas submetidas aos diferentes sistemas de manejo, nas profundidades de 0-0,20; 0,20-0,40 e 0,40-0,60 metros, sendo retiradas num ponto situado nas entrelinhas da cana-de-açúcar. Os resultados obtidos foram submetidos a análise de variância e as médias comparadas pelo teste de Tukey, a 5% de significância. Estudos de correlações simples foram realizados entre algumas variáveis medidas. Os resultados permitiram concluir que os diferentes sistemas de manejo investigados promoveram alterações nas propriedades físicas e químicas e no estado de agregação do solo. Os parâmetros de consistência do solo apresentaram tendência de aumento em seus valores de umidade com o incremento do carbono orgânico total (COT) do solo, promovido pela adição de resíduos da cana-de-açúcar. Os estudos de correlações simples entre o carbono orgânico total (COT) e os índices de estabilidade de agregados investigados apresentaram correlações significativas (p<0,01) e positivas. Os sistemas de manejo que receberam adição de resíduos da cana-de-açúcar denotaram menor degradação nas propriedades físicas e químicas do solo, em relação ao solo sob mata nativa (MN).

Long-term use of management systems result in alteration in physical and chemical soil properties and its intensity is related to time, soil and climate conditions. Physical properties are more susceptible to changes by the tillage system, while chemical properties by the residue management and nutrient application, resulting in different responses of crops growth and yield. This study was performed in order to evaluate long-term effect of applying soil tillage systems (NT = no-till; CP = chisel plow + 1 secondary disking; CT = primary + 2 secondary disking; CTb = CT with crop residues burned; and CTr = CT with crop residues removed from the field) and nutrient sources (C = control, without nutrient application; MF = mineral fertilizers according official recommendation for each crop; PL = 5 Mg ha-1 of wet matter of poultry litter; CM = 60 m3 ha-1 of liquid cattle manure; and SM = 40 m3 ha-1 of liquid swine manure) on soil properties and crop production. Soil physical and hydraulic properties and aggregate stability were evaluated at the end of ninth year of the experiment and in five sampling times throughout the tenth year; soil mechanical properties related to soil strength and penetration resistance were determined for some treatments combinations in the tenth year; soil cover, temperature and moisture were determined throughout corn cycle in 2003/2004 crop season, when corn growth and yield were also measured. No-till showed greater bulk density and lower macroporosity and total porosity after tillage and seeding operations, but the differences reduced over time. All tillage systems showed higher compaction degree at depth around 15 cm. Greater mean diameter of air-dry aggregates were found in tillage treatments and layers with higher bulk density, showing close relation between these two parameters. Wet-aggregate stability, on the other hand, was affected by aggregate moisture previous to wet-sieving determination, and greater values were found in tillage treatments where residues were kept in the field. At superficial layer of no-till was observed higher soil strength, as determined by the precompression stress, and to penetration resistance in untrafficked interrow. In seeding row and recent trafficked interrow the differences in penetration resistance among tillage systems were smaller. Higher soil temperature and daily amplitude were found in tilled treatments, mainly at the beginning of corn cycle. After rainfall events, soil moisture reduced faster in chisel plow system, followed by conventional tillage. Higher moisture content and lower water tension was found in no-till system even in long period with hydric deficits, resulting in higher water storage and availability to crops. Higher water availability seems to be the main factor in determining higher crop growth and yield in no-till treatment. Nutrient sources treatments had small effect on physical soil properties, but high effect on chemical properties and crop growth and yield. Greater growth and yield were observed with poultry litter and swine manure application, because of residual and immediate effect of nutrient application through these materials. / A utilização continuada de diferentes sistemas de manejo determina alterações nas propriedades físicas e químicas do solo, cuja intensidade depende do tempo de uso e das condições edafoclimáticas. As propriedades físicas são mais afetadas pelos sistemas de preparo enquanto que as propriedades químicas pelo manejo dos resíduos das culturas e pela aplicação de nutrientes, resultando em respostas diferenciadas em termos de crescimento e produção das culturas. O efeito de sistemas de manejo sobre as propriedades do solo e produção de culturas foi estudado em um experimento conduzido desde 1994 na Estação Experimental da Epagri de Campos Novos, em um Nitossolo Vermelho. Os tratamentos de manejo do solo foram constituídos de uma combinação de cinco sistemas de preparo (PD = plantio direto; PE = preparo com escarificador + 1 gradagem; PC = lavração + 2 gradagens; PCq = PC com resíduos queimados e; PCr = PC com resíduos retirados) e cinco fontes de nutrientes (TT = testemunha, sem aplicação de nutrientes; AM = adubação mineral de acordo com a recomendação para cada cultura de verão; EA = 5 Mg ha-1 ano-1 de matéria úmida de cama de aviário; EB = 60 m3 ha-1 ano-1 de esterco líquido de bovinos e; ES = 40 m3 ha-1 ano-1 de esterco líquido de suínos). Foram avaliadas algumas propriedades físicas do solo associadas à forma da estrutura e a estabilidade de agregados após nove anos de condução do experimento e em cinco épocas durante o décimo ano; propriedades mecânicas e resistência à penetração foram determinadas em algumas combinações de tratamentos no décimo ano; temperatura e umidade do solo foram determinadas durante o ciclo da cultura do milho na safra 2003/2004, quando também foram avaliados o crescimento da parte aérea e sistema radicular do milho, bem como a produção de massa seca das culturas de cobertura de inverno e de grãos de milho. O PD apresentou maior densidade e menor macroporosidade e porosidade total logo após as operações de preparo e semeadura, mas estas diferenças reduziram com o passar do tempo. Todos os sistemas de preparo apresentaram maior estado de compactação na camada de 5 a 20 cm de profundidade após seis meses da última operação de preparo. Maior diâmetro médio de agregados secos ar foram observados nos tratamentos e profundidades com maior densidade do solo, indicando estreita associação entre estas duas variáveis. A estabilidade dos agregados, por sua vez, foi afetada por pequenas variações na umidade das amostras por ocasião da análise e maiores valores de estabilidade foram encontrados nos tratamentos de preparo com manutenção da palha na lavoura. Nas camadas superficiais do PD foi observada maior resistência mecânica à deformação, estimada pela tensão de pré-consolidação, e à penetração de raízes nas entrelinhas de semeadura sem tráfego recente. Na linha de semeadura e na entrelinha com tráfego recente as diferenças da resistência à penetração entre os sistemas de preparo foram menores. Maior temperatura do solo e maior amplitude diária foram observadas nos sistemas com maior revolvimento do solo, principalmente no início do ciclo da cultura do milho. Na camada superficial, após a ocorrência de chuvas, a umidade do solo reduziu mais rapidamente no PE, seguido do PC. No PD foi observado maior teor de umidade nesta camada mesmo em período prolongado de déficit hídrico, indicando ma ior armazenamento e disponibilidade de água para as plantas. Os tratamentos de aplicação de fontes de nutrientes tiveram pouco efeito sobre as propriedades físicas, hídricas e mecânicas do solo e sobre a temperatura e armazenamento de água, mas foram determinantes para o crescimento vegetativo e produção das culturas. Maiores crescimento e produção foram observados nos tratamentos com aplicação de cama de aviário e de esterco de suínos, resultado do efeito residual e imediato da aplicação destes materiais ao longo de nove anos. Entre os sistemas de preparo, a produção foi maior no PD, provavelmente em função do maior armazenamento e disponibilidade de água, já que a fertilidade do solo neste tratamento era inferior ao PE e PC ao final do nono ano.

Currently there is no suitable and commonly used device for volumetric quantification of snowmelt erosion in the Czech Republic (CR). The determination of erosion rate in the catchment is a essential prerequisite for the correct design of conservation measures. The thesis tries to offer the possible ways of monitoring the snowmelt erosion, compares individual methods and defines their optimal use. In the first year of the research, a runoff plot was developed to capture sheet erosion. The thesis compares also the methods using mobile devices - erosion bridge method and UAV photogrammetry - as effective instrument for snowmelt erosion monitoring. So far, no attention has been paid to snowmelt erosion in CR. Therefore, the thesis focuses mainly on the analysis of causal factors specific to this type of erosion - the erosion potential of snow cover and the possible soil erodibility changes due to freeze-thaw cycles. The thesis assesses the rate of snowmelt erosion risk in selected climatically different catchments and its changes in recent years. shows the timeliness of the problem. In the end, the thesis presents possibilities for solving the problem. The thesis claims the problem of snowmelt erosion actual and offers its possible solution.

Microorganisms interact with different soil components, such as varying substrates and soil minerals, to drive soil processes and functionality. They can be influenced by the environment, but they themselves can influence their environment by their activities, for example through the production of extracellular enzymes and extracellular polymeric substances (EPS). The formation and stability of aggregates as the backbone of the soil structure, for instance, are thought to be largely influenced by soil microorganisms, or vice versa. There remain, however, open questions as to whether and how microorganisms can influence soil aggregation. While microbes are influencing their environment their interaction with the soil minerals could also change their responses upon adsorption - affecting their influence on soil aggregation. Therefore, the overarching goal of this thesis was to investigate the effect of soil minerals, in particular clay content, on the composition and activity of soil microbial community, with a specific focus on enzyme activities and EPS. Finally, the microbial control of soil aggregation through the influence of substrate availability was explored. In total, two adsorption experiments and two incubation experiments were conducted using soils manipulated experimentally with increasing clay content. The sandy soil was amended with different amounts of soil minerals (i.e. montmorillonite) to achieve a gradient in clay content. For the first incubation experiment, organic substrates differing in decomposability (i.e., starch and cellulose) were added to the soil to stimulate microbial activities and incubated for 80 days. Soil samples from the first incubation experiment were analysed after 0, 3, 10, 20, 40 and 80 days for enzyme activities, microbial community composition, biomass C, EPS-protein and polysaccharide. Additionally, the geometric mean diameter and mean weight diameter of the soil aggregates were determined as measures of aggregate formation and stability, respectively. The first adsorption experiment examined the effect of soil mineral phases on the activities of extracellular enzymes using commercially available extracellular enzymes (α-glucosidase) added to the soil. The second adsorption and incubation experiment investigated the persistence of extracellular enzyme activities (commercially available α-amylase and cellulase) affected by soil minerals. For further insight into how other soil minerals affect extracellular enzymes, kaolinite and goethite in addition to montmorillonite were included in the second adsorption and incubation experiment. The prepared complexes (enzyme + soil and/or soil minerals) from the second adsorption experiment were incubated for 100 days. Further analytical methods include the determination of enzyme activities, microbial biomass C, extraction and quantification of the soil EPS, protein analyses, DNA isolation, DGGE, qPCR and Illumina sequencing. The adsorption experiment showed that extracellular enzyme activities decreased with increasing clay contents. In contrast, such an inhibitory effect on microbial enzyme activity was only observed directly in the incubation experiment after the stimulation of in-situ microorganisms for extracellular enzyme production through substrate addition. Higher extracellular enzyme activities at later incubation days in soils with high clay content suggested an adaptation of the microbial community in response to soil clay content and/ or persistence of extracellular enzymes by adsorption to mineral surfaces. However, the second adsorption experiment showed that the high specific activity and persistence of the enzymes were constrained by the availability of sorption sites. It is therefore reasonable to assume that soil mineral phases support microorganisms in less-sorptive environments by sparing energy on enzyme production, since even a small enzyme release could already propel sufficient activities to degrade target carbon substrates. Starch amendment accelerated respiration and microbial biomass much more than cellulose. While microbial community differed depending on the C substrate (starch or cellulose) added, clay addition had a stronger influence on alpha diversity than substrate addition. Although the production of EPS-protein was closely linked to the provision of additional substrates, the addition of clay minerals resulted in more EPS production than when no additional clay was present. By correlating soil aggregation (stability and formation) with the recorded microbial parameters (that is biomass C, EPS-protein and EPS-polysaccharide), both EPS-protein and EPS-polysaccharide exhibited a significant control on aggregate formation and microbial processes, though, surprisingly, more strongly with high clay content. It was observed that EPS is only a transient compound, which initiates aggregate formation, but clay content plays a more significant role in long-term aggregate stabilization. Overall, this thesis contributed to our knowledge about the interaction of microorganisms with the soil mineral phase and their influence on soil structural stability. The findings established that soil minerals shape the composition and activity of microbial communities. In turn, the microbial production of EPS seems to be more significant for aggregate formation than stability. The results on the effect of soil minerals on extracellular activities provided a paradigm that the persistence of enzyme activities by adsorption does not always hold. Producing EPS might contribute to microbial adaptation that mitigates the negative effect of adsorption on extracellular enzymes. It might also be probable that the EPS become a substance of degradation for the extracellular enzymes. Overall, the results indicated that in clay-rich soils the process leading to extracellular enzyme persistence can be stochastic, depending on multiple factors including sorption sites and substrate availability. Labile organic C clearly plays a role in aggregate formation by supporting EPS production. However, increasing clay content enhanced aggregate stability, promoted the development of distinct microbial communities and increased EPS production. The discrepancy so observed in the contribution of the two EPS parameters, EPS polysaccharide and protein, on soil aggregation points to the need for inclusion of different EPS compositions in future studies relating to soil aggregation.

Human activities on land have a direct and cumulative impact on water and other natural resources within a catchment. This land-use change can have hydrological consequences on the local and regional scales. Sound catchment assessment is not only critical to understanding processes and functions but also important in identifying priority management areas. The overarching goal of this doctoral thesis was to design a methodological framework for catchment assessment (dependent upon data availability) and propose practical catchment management strategies for sustainable water resources management. The Nyangores and Ruiru reservoir catchments located in Kenya, East Africa were used as case studies. A properly calibrated Soil and Water Assessment Tool (SWAT) hydrologic model coupled with a generic land-use optimization tool (Constrained Multi-Objective Optimization of Land-use Allocation-CoMOLA) was applied to identify and quantify functional trade-offs between environmental sustainability and food production in the ‘data-available’ Nyangores catchment. This was determined using a four-dimension objective function defined as (i) minimizing sediment load, (ii) maximizing stream low flow and (iii and iv) maximizing the crop yields of maize and soybeans, respectively. Additionally, three different optimization scenarios, represented as i.) agroforestry (Scenario 1), ii.) agroforestry + conservation agriculture (Scenario 2) and iii.) conservation agriculture (Scenario 3), were compared. For the data-scarce Ruiru reservoir catchment, alternative methods using digital soil mapping of soil erosion proxies (aggregate stability using Mean Weight Diameter) and spatial-temporal soil loss analysis using empirical models (the Revised Universal Soil Loss Equation-RUSLE) were used. The lack of adequate data necessitated a data-collection phase which implemented the conditional Latin Hypercube Sampling. This sampling technique reduced the need for intensive soil sampling while still capturing spatial variability. The results revealed that for the Nyangores catchment, adoption of both agroforestry and conservation agriculture (Scenario 2) led to the smallest trade-off amongst the different objectives i.e. a 3.6% change in forests combined with 35% change in conservation agriculture resulted in the largest reduction in sediment loads (78%), increased low flow (+14%) and only slightly decreased crop yields (3.8% for both maize and soybeans). Therefore, the advanced use of hydrologic models with optimization tools allows for the simultaneous assessment of different outputs/objectives and is ideal for areas with adequate data to properly calibrate the model. For the Ruiru reservoir catchment, digital soil mapping (DSM) of aggregate stability revealed that susceptibility to erosion exists for cropland (food crops), tea and roadsides, which are mainly located in the eastern part of the catchment, as well as deforested areas on the western side. This validated that with limited soil samples and the use of computing power, machine learning and freely available covariates, DSM can effectively be applied in data-scarce areas. Moreover, uncertainty in the predictions can be incorporated using prediction intervals. The spatial-temporal analysis exhibited that bare land (which has the lowest areal proportion) was the largest contributor to erosion. Two peak soil loss periods corresponding to the two rainy periods of March–May and October–December were identified. Thus, yearly soil erosion risk maps misrepresent the true dimensions of soil loss with averages disguising areas of low and high potential. Also, a small portion of the catchment can be responsible for a large proportion of the total erosion. For both catchments, agroforestry (combining both the use of trees and conservation farming) is the most feasible catchment management strategy (CMS) for solving the major water quantity and quality problems. Finally, the key to thriving catchments aiming at both sustainability and resilience requires urgent collaborative action by all stakeholders. The necessary stakeholders in both Nyangores and Ruiru reservoir catchments must be involved in catchment assessment in order to identify the catchment problems, mitigation strategies/roles and responsibilities while keeping in mind that some risks need to be shared and negotiated, but so will the benefits.:TABLE OF CONTENTS DECLARATION OF CONFORMITY........................................................................ i DECLARATION OF INDEPENDENT WORK AND CONSENT ............................. ii LIST OF PAPERS ................................................................................................. iii ACKNOWLEDGEMENTS ..................................................................................... iv THESIS AT A GLANCE ......................................................................................... v SUMMARY ............................................................................................................ vi List of Figures......................................................................................................... x List of Tables........................................................................................................... x ABBREVIATION..................................................................................................... xi PART A: SYNTHESIS 1. INTRODUCTION ............................................................................................... 1 1.1 Catchment management ...................................................................................1 1.2 Tools to support catchment assessment and management ..............................4 1.3 Catchment management strategies (CMSs)......................................................9 1.4 Concept and research objectives.......................................................................11 2. MATERIAL AND METHODS................................................................................15 2.1. STUDY AREA ..................................................................................................15 2.1.1. Nyangores catchment ...................................................................................15 2.1.2. Ruiru reservoir catchment .............................................................................17 2.2. Using SWAT conceptual model and land-use optimization ..............................19 2.3. Using soil erosion proxies and empirical models ..............................................21 3. RESULTS AND DISCUSSION..............................................................................24 3.1. Assessing multi-metric calibration performance using the SWAT model...........25 3.2. Land-use optimization using SWAT-CoMOLA for the Nyangores catchment. ..26 3.3. Digital soil mapping of soil aggregate stability ..................................................28 3.4. Spatio-temporal analysis using the revised universal soil loss equation (RUSLE) 29 4. CRITICAL ASSESSMENT OF THE METHODS USED ......................................31 4.1. Assessing suitability of data for modelling and overcoming data challenges...31 4.2. Selecting catchment management strategies based on catchment assessment . 35 5. CONCLUSION AND RECOMMENDATIONS ....................................................36 6. REFERENCES ............................ .....................................................................38 PART B: PAPERS PAPER I .................................................................................................................47 PAPER II ................................................................................................................59 PAPER III ...............................................................................................................74 PAPER IV ...............................................................................................................88

This study is the first to consider how the combination of root physical effects, microbial production of EPS, and root effects on the hydrodynamic boundary layer could influence streambank soil erodibility. Specifically, the goal of this research was to quantify the physical and biological effects of roots on streambank fluvial erosion. A series of laboratory-scale erosion tests were conducted using a mini jet erosion testing device and a recirculating flume channel to address this goal. Several soil and vegetation factors that influence fluvial entrainment, like extracellular polymeric substances (EPS), soil aggregate stability and root length density, were measured following erosion testing. For flume experiments, three streambank boundary conditions were constructed to simulate unvegetated streambanks, as well as streambanks with herbaceous and woody roots. Soil treatments were also created to represent unamended and organic matter (OM) amended soil either without roots (bare soil), with synthetic roots, or with living roots (Panicum virgatum). Median soil erosion rates along the simulated rooted boundaries were two to ten times higher compared to the unvegetated boundary due to protruding root impacts on the boundary layer. In flume experiments, median erosion rates were 30% to 72% lower for unamended soils containing compacted synthetic root fibers as compared to bare soil samples. Adding both OM and fibers to the soil had a greater effect; the median erosion rate reductions of live rooted treatments (95% to 100%) and synthetic rooted + OM treatments (86% to 100%) were similar and statistically lower than bare soil controls. Stimulated microbial production of EPS proteins were significantly correlated with increased erosion resistance in OM-amended treatments while OM treatments had significantly lower EPS carbohydrates compared to unamended treatments. In summary, while sparsely spaced roots exposed on streambanks may increase soil erosion rates due to impacts on the hydrodynamic boundary layer, overall results highlight how the synergistic relationship between root fibers and soil microbes can significantly reduce streambank soil erodibility due to fiber reinforcement and EPS production. / Doctor of Philosophy / Plant roots are known to protect streambank soils from erosion by water; however, exactly how roots provide this protection has remained unclear. Among other things, roots can influence streambank soil erosion by holding soil together through a thick root network, interacting with soil microorganisms to stimulate the release of "sticky" organic compounds called extracellular polymeric substances (EPS), and altering the force of the water against the streambank. This research aimed to quantify and compare the relative importance of these three mechanisms on streambank soil erosion using a mini jet erosion testing device and an indoor recirculating flume channel. To do this in the flume, three walls were constructed to simulate unvegetated streambanks, as well as streambanks with herbaceous and woody roots. In greenhouse settings, soil treatments were also created to represent unamended and organic matter (OM) amended soil either without roots (bare soil), with artificial roots, or with living roots (Panicum virgatum). While roots protruding out of streambanks appeared to increase median soil erosion rates due to the impact of roots on near-bank flow, artificial roots in the soil and OM amended soils reduced soil erosion rates. Specifically, OM amendments stimulated the production of EPS proteins, leading to improved soil stability and increased soil resistance to erosion by water. Overall results highlight how the synergistic relationship between root fibers (living roots and artificial roots) and soil microbes can significantly reduce streambank soil erodibility due to root binding and microbial production of EPS. While plant roots naturally provide both fibers and EPS to soils, these materials could be incorporated into fill soils during construction to rapidly increase soil erosion resistance following levee construction and stream restoration projects.

Das Ziel dieser Arbeit war es, die Auswirkungen verschiedener Bodennutzungssysteme auf ausgewählte physiko-chemische Bodeneigenschaften und pflanzenbauliche Parameter auf sandigen Böden auf den Dauerfeldversuchsflächen in Berlin-Dahlem und Dedelow zu untersuchen. Ein erster Arbeitsschwerpunkt am Standort Berlin-Dahlem bestand darin, die Wirkungen verschiedener Bodenbearbeitungstiefen (17 cm und 28 cm) in Abhängigkeit der drei Faktorstufen - mit und ohne Kalkdüngung, mit und ohne Stallmistdüngung, flache und tiefe Bodenbearbeitung - zu ermitteln. Im zweiten Arbeitsschwerpunkt wurden in einer fünffeldrigen Fruchtfolge am Standort Dedelow Vergleiche verschiedener Verfahren der konventionellen und konservierenden Bodenbearbeitung und deren Effekte untersucht. Die Durchdringungswiderstandmessungen in Berlin-Dahlem zeigten nach langjähriger Bodenbearbeitung höhere Bodenfestigkeitswerte in der tieferen Bodenbearbeitungsvariante als in der flachen Variante. Die wasserstabilen Aggregate in Berlin-Dahlem wiesen in der flachen Bodenbearbeitung höhere Werte auf. Die ermittelten Wasserspeicherkurven in Berlin-Dahlem zeigten in der flachen Bodenbearbeitungsvariante für die ausgewählten Parzellen in 10-15 cm Bodentiefe im Vergleich zu der tieferen Variante tendenziell höhere nutzbare Feldkapazitätswerte. In Dedelow zeigten die Wasserretentionskurven unter verschiedenen Bodenbearbeitungsverfahren unregelmäßige Streuungen auf. Die höchsten Gesamtkohlenstoffgehaltswerte wurden in der flachen Bodenbearbeitung unter dem Prüfglied „mit Kalk- und mit Stallmist“ gedüngten Parzellen erzielt. In Dedelow zeigten die Gesamtkohlenstoffgehalte zwischen konservierender und konventioneller Bodenbearbeitung in 10-15 cm Bodentiefe kaum Unterschiede. Der Einfluss von Düngung und Bodenbearbeitungstiefen auf den Kornertrag bei Hafer war mit einem Ertrag von 29,2 dt ha-1 am stärksten am Standort Dedelow in der tiefen Bodenbearbeitung unter dem Prüfglied „mit Kalk- und ohne Stallmistdüngung“. / On the basis of various long-term field trials it was the goal to investigate the influence of different tillage systems on soil physical, soil chemical and crop parameters on sandy loamy locations in Berlin-Dahlem and Dedelow. The first focus of the work in Berlin-Dahlem was to investigate the effects between different tillage depths (17 cm and 28 cm) and the selected factors “with and without liming”, “with and without manure fertilization” and “shallow and deep tillage”. The second focus was on a five-field crop rotation site in Dedelow to compare different methods of conventional and conservation tillage and their effects. The penetration resistance values in Berlin-Dahlem showed after long-time tillage in the deep soil tillage system higher compactions compared to shallow tillage systems. The soil aggregate stability values in Berlin-Dahlem showed in the shallow tillage higher values. The obtained soil water retention curves in Berlin-Dahlem showed an increase of the available water capacity for the selected plots in the shallow soil tillage system compared to the deep tillage system in the 10 - 15 cm soil depth. The soil water retention curves showed irregular variations under the different tillage systems in Dedelow. The highest total carbon content were observed in the shallow tillage system in the "with lime and with farmyard manure" treatments. In general, however, the total carbon content predominate nearly the same amounts in 10 - 15 cm soil depth in both conservation and conventional tillage systems in Dedelow. The influence of fertilization and tillage depth on grain yield in oats showed the maximum value as 29,2 dt ha-1 in the deep tillage system in the "with lime and without farmyard manure" treatments.

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Die bei der Biogasproduktion anfallenden Gärreste werden als organische Dünger im Pflanzenbau eingesetzt. Infolge des Vergärungsprozesses unterscheiden sich Gärreste von herkömmlichen organischen Düngern. Daraus könnten sich spezifische positive oder negative Wirkungen auf Bodenfruchtbarkeit und Pflanzen ergeben, die Gegenstand dieser Arbeit sind. In einem sechsjährigen Feldversuch (Energiepflanzenfruchtfolge, sandiger Boden) wur- den die Düngeeffekte von fünf verschiedenen Gärresten mit denen von Rindergülle, Stallmist und mineralischem Dünger (KAS) verglichen. Zur umfassenden Charakterisie- rung der Bodenfruchtbarkeit erfolgten Untersuchungen aus den Bereichen Bodenchemie, -physik, -mikrobiologie und Pflanzenbau, wobei die Humusdynamik einen Schwerpunkt bildete. Die Mengenkalkulation der Düngung basierte auf der gleichen Gabe organi- schem C mit einem N-Ausgleich durch KAS. Es ergaben sich für Gärreste gegenüber KAS überwiegend positive Effekte auf Hu- musgehalt, Aggregatstabilität und bakterielle Aktivität und Diversität. Diese Effekte waren denen von Rindergülle und Stallmist ähnlich. Möglicherweise besteht aber durch Gärrestdüngung ein erhöhtes Risiko von P- und K-Überschüssen sowie N-Verlusten. Eine erhöhte Benetzungshemmung wurde nicht gefunden. Die mikrobielle Gemeinschaft des Bodens zeigte eine spezifische Beeinflussung durch die Gärreste in der funktionellen, jedoch nicht in der genetischen Struktur. Die N-Verfügbarkeit war deutlich geringer als die von KAS, wodurch sich für Grünroggen Mindererträge ergaben. Für Silomais und Sorghum fand sich bei kombinierter Anwendung mit KAS ein zu KAS ähnliches Ertragsniveau. Gärreste haben analog zu herkömmlichen organischen Düngern bei effizientem Einsatz das Potential zu KAS vergleichbare Erträge zu erzielen und gleichzeitig die Bodenfrucht- barkeit zu fördern. Diese Schlussfolgerung ist im Kontext der spezifischen Standort- und Versuchsbedingungen zu sehen und sollte durch eine längere Versuchszeit abgesichert werden. / Digestates arising during biogas production are used as organic fertilizers in agriculture. Due to the fermentation process, digestates have different properties from traditional organic fertilizers. This may result in specific positive or negative effects on soil fertility and plants, which are subject of this work. In a six year field experiment (energy crop rotation, sandy soil) fertilizer effects of five different digestates were compared with cattle slurry, farm yard manure and mineral fertilizer (KAS). For a comprehensive characterization of soil fertility effects, methods from the fields of soil chemistry, physics, microbiology and plant science were applied. One special focus of these investigations was humus dynamics. Manure doses were based on the same dose of organic carbon, resulting different N-doses were compensated by KAS. Compared with KAS, digestates showed predominantly positive effects on humus con- tent, soil aggregate stability and bacterial activity and diversity. These effects of di- gestates were similar to those of cattle slurry and farm yard manure. There may be an increased risk of P and K oversupply and N losses as a result of digestate fertilization. An increased soil water repellency was not found. The soil bacterial community was specifically influenced by digestates regarding its functional, but not regarding its genetic structure. Saprotrophic fungy were reduced by some digestates in comparison to KAS. N availability was considerably lower than of KAS, resulting in yield depressions of forage rye. For silage maize and sorghum, digestates combined with KAS equaled the yield level of KAS. If efficiently applied, digestates have like other organic fertilizers the potential to produce equal yields as KAS whilst enhancing soil fertility. This conclusion is restricted to the specific conditions of experimental site and design and must be verified during a longer experimental period.