Decomposition and N dynamics of grain-corn residues were investigated in a field study in southwestern Quebec, with particular reference to the roles of different plant parts (stems, leaves etc.) in determining overall residue mass loss and N content. A litterbag study was conducted, with surface and buried placements in plots under three tillage systems (no-till, reduced tillage, and conventional tillage, established five years before litterbag placement). Residue mass loss and N content were monitored over a two-year period. Separate data were obtained for leaves, stems, husks, and cobs. Net values for all residues combined were calculated taking into account initial proportions of each plant part at harvest. Overall estimates were made based on residue depth-distribution typical of each tillage system. A spreadsheet-based model of surface residue mass loss was developed, incorporating litterbag mass and other surface-residue data, in order to determine how well litterbag results predicted surface residue mass loss in the field, and to test alternative assumptions regarding residue decomposition and/or burial. Buried residues lost mass more quickly than surface residues, as expected. Thus residue breakdown would be fastest in a conventional system, slowest under no-till, and intermediate with reduced tillage. Substantial decreases in mass and residue N content occurred between fall placement and first sampling in spring, despite low temperatures for much of this period. Mass loss in the first period was substantial for stems as we as husks and leaves. Cobs decomposed most slowly throughout. Nitrogen dynamics, including effects of depth on residue N content, differed greatly by residue type. All the lower-N residues (cobs, husks, stems) immobilized N at some point. However, during the two-year study, N immobilization by one or more residue types was always counterbalanced or exceeded by N release by other residue, at least for the sampling intervals included. Pa

Thesis (MSc)--Stellenbosch University, 1955. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

O pisoteio dos animais favorece o processo de compactação do solo em áreas de Integração Lavoura Pecuária. Essa compactação apresenta efeitos negativos, dificultando o desenvolvimento de raízes, a disponibilidade de nutrientes, água e aeração, ocasionando perdas na produção, tornando-se indispensável à avaliação dos atributos físicos do solo para o monitoramento da qualidade do solo. A matéria orgânica do solo pode ser utilizada para avaliar a qualidade do solo, por apresentar relação com os atributos químicos, físicos e biológicos do solo. Sistemas de manejo conservacionistas com o plantio direto, juntamente com sistemas de integração entre lavoura e pecuária estão sendo utilizados para manter e até mesmo aumentar os teores de matéria orgânica do solo. Para avaliar estas questões está instalado na cidade de Guarapuava, PR, desde 2006, um experimento de integração lavoura – pecuária com ovinos, sob um Latossolo Bruno álico com textura argilosa, sob um clima classificado como Cfb. O estudo teve objetivo avaliar os atributos físicos do solo e quantificar o estoque de carbono orgânico do solo e sua compartimentalização em sistema submetido a quatro doses de N (0, 75, 150 e 225 kg ha-1) na pastagem de inverno, formada pelo consórcio de aveia preta (Avena strigosa) e azevém comum (Lolium multiflorum) e o efeito do pastejo (com e sem). As avaliações de densidade, porosidade total, macroporosidade, microporosidade, agregação e estoques de carbono foram realizadas em duas fases: Fase pecuária (após a saída dos animais da área) e fase lavoura (após o cultivo de milho). As coletas das mostras de solo foram realizadas nas camadas de 0-0,5, 0,05-0,10, e 0,10-0,20 m. Os dados foram submetidos à análise de variância e as hipóteses testadas pelo teste F (p<0,05). Para os dados de efeito quantitativo foram realizadas análises de regressão e os de efeito qualitativo utilizou-se o teste de médias. Nas regressões não significativas utilizou-se a média dos tratamentos e o desvio padrão. O pisoteio animal ocasionou um aumento na densidade do solo na camada de 0,10-0,20 m. A dose de 225 kg de N ha-1 na pastagem de inverno aumentou a porosidade total do solo em 8% em relação a dose 0 kg de N ha-1 na fase lavoura. O pastejo não influenciou na macroporosidade do solo. O Diâmetro médio geométrico dos agregados na fase após pastejo na camada superficial foi prejudicado pelo pastejo. As doses de nitrogênio aplicadas na pastagem de inverno e o pastejo não influenciam nos estoques de carbono orgânico total (COT) e que também não é influenciado pelas doses de nitrogênio aplicadas na pastagem. O pastejo aumenta o estoque de carbono orgânico particulado (COP) na camada de 0,10-0,20 m na fase pecuária e causa no estoque de COP na camada de 0-0,5 m na fase lavoura. O carbono associado aos minerais (CAM) não é influenciado pelas doses de N aplicadas na pastagem, nem pelo pastejo. / The animal trampling favors the soil compaction process in sheep raising and crop production integrated systems. This compression has negative effects, hindering the development of roots, the availability of nutrients, water and aeration, causing production losses, making it essential for the assessment of soil physical attributes for monitoring soil quality. Soil organic matter can be used to assess the quality of the soil, due to its relationship with the chemical, physical and biological soil properties. Conservation management system with tillage, along with systems integration between crops and livestock are being used to maintain and even increase the levels of soil organic matter. For that, a field experiment was carried out over a Oxisol clayey Alic in Guarapuava, PR, from de 2006 one. experiment sheep raising and crop production integrated systems The climate classified as Cfb .. The study was to evaluate the soil physical properties and quantify the stock of soil organic carbon and its compartmentalization in system integration crop - livestock with sheep under four nitrogen rates (0, 75, 150 and 225 kg ha-1) in the winter pasture, formed by the consortium oat (Avena strigosa) and ryegrass (Lolium multiflorum) and the effect of grazing (with and without). The soil samples blades density evaluations, total porosity, macro and micro, aggregation and carbon stocks were held in two phases: Phase livestock (after removal of the animals of the area) and phase crop (after maize cultivation). The collection of soil samples were carried out in layers of 0-0.5, 0.05-0.10, 0.10-0.20 and m. Data were subjected to analysis of variance and the hypotheses tested by the F test (p <0.05). For the quantitative effect data regression and the qualitative effect used the test medium. In non-significant regressions used the average and standard deviation treatments. The animal trampling caused an increase in bulk density in the 0.10-0.20 m layer. The dose of 225 kg N ha-1 in winter pasture increased total soil porosity at 8% compared to dose 0 kg N ha-1 in the crop stage. The grazing had no effect on soil macroporosity. GMD of aggregates in the phase after grazing the surface layer was damaged by grazing. Nitrogen rates used in the winter pasture and grazing not influence the total organic carbon stocks. The TOC is not influenced by nitrogen fertilization on grassland. The grazing increases the stock of POC in the 0.10-0.20 m layer livestock phase and cause the stock of POC in the 0-0.5 m layer in the crop stage. The MAC is not influenced by N rates applied in the pasture or by grazing.

O pisoteio dos animais favorece o processo de compactação do solo em áreas de Integração Lavoura Pecuária. Essa compactação apresenta efeitos negativos, dificultando o desenvolvimento de raízes, a disponibilidade de nutrientes, água e aeração, ocasionando perdas na produção, tornando-se indispensável à avaliação dos atributos físicos do solo para o monitoramento da qualidade do solo. A matéria orgânica do solo pode ser utilizada para avaliar a qualidade do solo, por apresentar relação com os atributos químicos, físicos e biológicos do solo. Sistemas de manejo conservacionistas com o plantio direto, juntamente com sistemas de integração entre lavoura e pecuária estão sendo utilizados para manter e até mesmo aumentar os teores de matéria orgânica do solo. Para avaliar estas questões está instalado na cidade de Guarapuava, PR, desde 2006, um experimento de integração lavoura – pecuária com ovinos, sob um Latossolo Bruno álico com textura argilosa, sob um clima classificado como Cfb. O estudo teve objetivo avaliar os atributos físicos do solo e quantificar o estoque de carbono orgânico do solo e sua compartimentalização em sistema submetido a quatro doses de N (0, 75, 150 e 225 kg ha-1) na pastagem de inverno, formada pelo consórcio de aveia preta (Avena strigosa) e azevém comum (Lolium multiflorum) e o efeito do pastejo (com e sem). As avaliações de densidade, porosidade total, macroporosidade, microporosidade, agregação e estoques de carbono foram realizadas em duas fases: Fase pecuária (após a saída dos animais da área) e fase lavoura (após o cultivo de milho). As coletas das mostras de solo foram realizadas nas camadas de 0-0,5, 0,05-0,10, e 0,10-0,20 m. Os dados foram submetidos à análise de variância e as hipóteses testadas pelo teste F (p<0,05). Para os dados de efeito quantitativo foram realizadas análises de regressão e os de efeito qualitativo utilizou-se o teste de médias. Nas regressões não significativas utilizou-se a média dos tratamentos e o desvio padrão. O pisoteio animal ocasionou um aumento na densidade do solo na camada de 0,10-0,20 m. A dose de 225 kg de N ha-1 na pastagem de inverno aumentou a porosidade total do solo em 8% em relação a dose 0 kg de N ha-1 na fase lavoura. O pastejo não influenciou na macroporosidade do solo. O Diâmetro médio geométrico dos agregados na fase após pastejo na camada superficial foi prejudicado pelo pastejo. As doses de nitrogênio aplicadas na pastagem de inverno e o pastejo não influenciam nos estoques de carbono orgânico total (COT) e que também não é influenciado pelas doses de nitrogênio aplicadas na pastagem. O pastejo aumenta o estoque de carbono orgânico particulado (COP) na camada de 0,10-0,20 m na fase pecuária e causa no estoque de COP na camada de 0-0,5 m na fase lavoura. O carbono associado aos minerais (CAM) não é influenciado pelas doses de N aplicadas na pastagem, nem pelo pastejo. / The animal trampling favors the soil compaction process in sheep raising and crop production integrated systems. This compression has negative effects, hindering the development of roots, the availability of nutrients, water and aeration, causing production losses, making it essential for the assessment of soil physical attributes for monitoring soil quality. Soil organic matter can be used to assess the quality of the soil, due to its relationship with the chemical, physical and biological soil properties. Conservation management system with tillage, along with systems integration between crops and livestock are being used to maintain and even increase the levels of soil organic matter. For that, a field experiment was carried out over a Oxisol clayey Alic in Guarapuava, PR, from de 2006 one. experiment sheep raising and crop production integrated systems The climate classified as Cfb .. The study was to evaluate the soil physical properties and quantify the stock of soil organic carbon and its compartmentalization in system integration crop - livestock with sheep under four nitrogen rates (0, 75, 150 and 225 kg ha-1) in the winter pasture, formed by the consortium oat (Avena strigosa) and ryegrass (Lolium multiflorum) and the effect of grazing (with and without). The soil samples blades density evaluations, total porosity, macro and micro, aggregation and carbon stocks were held in two phases: Phase livestock (after removal of the animals of the area) and phase crop (after maize cultivation). The collection of soil samples were carried out in layers of 0-0.5, 0.05-0.10, 0.10-0.20 and m. Data were subjected to analysis of variance and the hypotheses tested by the F test (p <0.05). For the quantitative effect data regression and the qualitative effect used the test medium. In non-significant regressions used the average and standard deviation treatments. The animal trampling caused an increase in bulk density in the 0.10-0.20 m layer. The dose of 225 kg N ha-1 in winter pasture increased total soil porosity at 8% compared to dose 0 kg N ha-1 in the crop stage. The grazing had no effect on soil macroporosity. GMD of aggregates in the phase after grazing the surface layer was damaged by grazing. Nitrogen rates used in the winter pasture and grazing not influence the total organic carbon stocks. The TOC is not influenced by nitrogen fertilization on grassland. The grazing increases the stock of POC in the 0.10-0.20 m layer livestock phase and cause the stock of POC in the 0-0.5 m layer in the crop stage. The MAC is not influenced by N rates applied in the pasture or by grazing.

Subsurface drainage has recently become common for agriculturally productive soils and key to maintain and improve crop production in poorly drained, frigid clay soils. The first study was conducted for four years (2014-17) at Casselton, ND to determine best combination of drainage, tillage and crop rotation for higher corn yield. Our finding suggested corn yield was highest with no drainage, CS and CH combination in years with drought conditions. The second study was conducted for three years (2015-17) to evaluate subsurface drainage spacing (9, 12, and 15m) and depth (0.9 and 1.2m) combination on corn, soybean and sugarbeet yields and residual soil nitrate-nitrogen (NO3-N) contents. Results indicated that 9 m drain spacing produced highest corn and soybean yield when average across three years in contrast with drain depth that has no effect on corn and soybean yield except for sugarbeet where the 1.2m depth yielded higher than the 0.9m depth. / North Dakota Corn Council / North Dakota Soybean Council / North Dakota Water Resources Research Institute

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Successful renovation of wastewater and sludge via land application depends upon sludge-induced soil changes associated with carbon (C) and nitrogen (N) cycles within the soil/plant system. The C, N, and hydrologic cycles within a soil/sludge system receiving a year-round, daily application of paper mill sludge were studied. Soil samples were collected from three locations on a land application site in the Piedmont of Virginia that had received papermill sludge applications for six, two, and no prior years. The average application rate was 4.4 cm/wk, each week of the year, with a N loading of 700 kg N ha⁻¹yr-⁻¹. The column study showed that C and N were still accumulating on the land application site after 6 years, but at a decreasing rate. Based on this study, C accumulation will level out after 13 years of application, but N will continue to accumulate for almost 30 years. As application period increased, soil bulk density increased in the O, A, and B horizons, the percentage of non-capillary porosity fell below 10% in the A horizon and approached zero in the B horizon, and there was a dramatic decrease in the soil's hydraulic conductivity in both the A and B horizons. Nitrogen leaching is expected to increase with time due to high amounts of N in the papermill sludge, a continued narrowing of the C:N ratio, a high percentage of nitrification, and low denitrification rates. Experimental timing and rates of sludge additions were imposed to alter the aerobic/anaerobic properties of the soil system to determine the conditions under which optimum C and N mineralization, nitrification, and denitrification would occur. Application rates were factorially arranged for single or multiple doses on a daily or alternating schedule. The C decomposition and N mineralization processes were both optimized with an increase in the length of cycle; they were maximized with an alternating 9 days on/9 off application schedule. The nitrification potential also increased with the length of cycling, with an average nitrification rate of 96%. Denitrification was minimal in all treatments, with an average denitrification rate of 16%. This was primarily attributed to movement of nitrate-N below the most biologically active zone in the soil column. Sludge renovation will ultimately depend upon the excess N being sequestered in plant biomass or denitrified. Proper management of these processes will ensure that wastes decompose, and that N is stored or evolved as a benign gas rather than leached at unacceptable levels. / Master of Science