Soil mineral N and soil water content at planting, biomass accumulation, yield and grain quality parameters (hectolitermass and protein percentage) were measured on an unfertilized and recommended-N-application treatment during two consecutive growing seasons (1997-1998). The trials were planted in a fallow-wheat-wheat cropping system at three representative localities in the summer rainfall region of South Africa. High levels of available soil water and mineral N were measured following the fallow period preceding the start of the trials in 1997. For example, soil water content was 81.7%, 69.6%, and 78.2% of DUL at Bethlehem, Kroonstad and Petrusburg respectively. Although comparable total soil profile water contents to 1997 were measured in 1998 at all three sites, the cultivation zone (0-400 mm) had a substantially lower soil water content. This was due to erratic rainfall distribution during the fallow period, which prevented effective soil cultivation management, subsequent soil water conservation and residue decomposition. Undecomposed residue in the cultivation layer at planting appeared to affect availability of soil mineral N to the growing crop. At planting in 1998, undecomposed crop residue amounted to 53.6% at Bethlehem, 32.5% at Kroonstad and 46.9% at Petrusburg of that added at harvest in 1997. Soil mineral N was lower at planting in 1998 compared to 1997 due to decomposing residue (C:N ratio of above 73) in the cultivation zone immobilizing soil mineral N. This reduced initial growth, N accumulation, yield, and grain protein percentage without additional fertilizer N. Distribution of soil mineral N showed notable amounts in the 600-1200 mm soil layers, with limited changes over the trial period. This was linked to low root exploration of these soil layers (10-15% of total root distribution). The ratios of soil mineral NH(4+):N0(3)- for the different soil layers indicated similar values over the trial period. Climatic data for the localities indicated differences in the amount and distribution of rainfall and temperatures during the study period, which influenced crop development, yield and grain protein percentage. At Bethlehem above average in-season rainfall was measured during 1997, at Kroonstad average rainfall and at Petrusburg below average in-season rainfall. Response to applied N at the localities varied in magnitude during 1997. Nitrogen application significantly increased N concentrations of plant components, N uptake, yield and grain protein percentage, although values for all these parameters were lower in 1998 than in 1997. Indeed higher yields were produced in 1997 (mean=1.838 t ha(-1)) compared to 1998 (mean=0.980 t ha(-1)). A significant yield response to applied N was measured at the two higher yielding localities in both cropping years, but there was no significant response at the lower yielding locality. The limiting factors appeared to be the availability of soil water and residual soil mineral N. From the calculated response functions, the variables soil water content at planting, soil mineral N content at planting, in-season rainfall, and added fertilizer N explained the bulk of the variations in grain protein percentage, plant N uptake, and yields. It was concluded that the present fertilizer N recommendation system for dryland wheat production, which is based on fertilizer response curves for specific yield potentials, should be augmented by using initial soil mineral N and water contents in the profile measured prior to planting. / Thesis (M.Sc.Agric.)-University of Natal, Pietermaritzburg, 2002.

In an attempt to investigate the cause of change in the competitive ability between monocots and dicots in a pastureland in Farnham, Quebec under CO2 enrichment, I chose to study the response of Plantago major (dicot) and Poa pratensis (monocot) grown in ambient and elevated CO2 chambers, hypothesizing that a large increase in root biomass of dicots would be observed under elevated CO 2. A transient stimulation of root biomass of Plantago major was found during the first month of CO2 exposure but disappeared later. / The second objective of this study was to examine the effect of 5 years of CO2 enrichment both on root biomass and on total C and N content of roots and soil in the pasture. The largest belowground growth was recorded for Taraxacum officinale. Plantago major responded by achieving the highest aboveground growth. / N content of CO2 enriched roots was reduced. This change in the elemental composition of root tissues might negatively affect the process of decomposition and therefore, the nutrient availability to soil microbes and plants. The observed reduction of NO3 in CO2 enriched soil maybe due to greater N immobilization caused by the expected increase in microbial populations.

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

Copy of author's previously published work inserted. / Bibliography: leaves 147-189. / xxi, 189 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This project examines the uptake of mineral N from the subsoil after anthesis and its effect on grain protein concentration (GPC) of wheat. The overall objective is to examine the importance of subsoil mineral N and to investigate the ability of wheat to take up N from the subsoil late in the season under different conditions of N supply and soil water availability. Greenhouse experiments investigate the importance of subsoil mineral N availability on GPC of wheat and the factors that contribute to the effective utilisation of N. The recovery of N from subsoil, the effect of split N application on GPC and short term N uptake by the wheat at different rooting densities are also studied. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1997

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.

Submitted by (edna.saturno@ufrpe.br) on 2017-04-11T12:30:28Z No. of bitstreams: 1 Felipe de Araujo Cabral.pdf: 2248759 bytes, checksum: f9bf08b2148a000ef1b3ba7f763e95db (MD5) / Made available in DSpace on 2017-04-11T12:30:28Z (GMT). No. of bitstreams: 1 Felipe de Araujo Cabral.pdf: 2248759 bytes, checksum: f9bf08b2148a000ef1b3ba7f763e95db (MD5) Previous issue date: 2013-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The aim of this study was to evaluate the biomass, chemical composition of the fodder and litter, Morphophysiological response of the plant at different distances from the trees in silvopastoral systems and compare this system with the monoculture (full sun) Zona da Mata of PE. The treatments were: association of Brachiaria decumbens pasture with the following tree legumes: “Sabiá” (Mimosa caesalpiniifolia I.) and gliricidia [Gliricidia sepium (Jacq.) Kunth ex Walp] and two additional treatments B. decumbens in the grassy moccultivo being an exclusive without nitrogen fertilization and another formed by grass fertilized with 60 kg N / ha / year. Response variables were measured at 5 different points (0 , 1.3, 2.7, 4.1 and 5.5 m away from the tree legume row), and randomly in monoculture system. The following responses were measured: percentage of litter, stem, leaf, canopy height, leaf area index (LAI), light interception (LI), herbage mass, N concentration in Brachiaria decumbens, SPAD index, litter mass, litter N, and soil fertility. Triple interaction (distance x grazing cycle x species) occurred for percentage of leaf litter, litter N, and light interception. The remaining variables showed interaction between distance x grazing cycle, except for the percentage of litter that showed significant differences (P <0.05) only among grazing cycles. Soil fertility did not differ (P < 0.05). Generally, there was an increase in the values of canopy height, LAI and LI with increasing distance from trees. Forage and litter N as well as SPAD index were higher near the tree double rows. In different periods of evaluation shows the contrast (P = 0.0001) than in silvopastoral systems N content in Brachiaria decumbens was higher when compared to monoculture with and without fertilizer, except in September 2010 and February 2011, Brachiaria decumbens in monoculture receiving N fertilization showed higher concentrations of N (1.02 and 1.7%, respectively) compared to silvopastoral system; Brachiaria intercropped with ‘Sabiá’ showed 0.9 and 1.64% for the months of September 2010 and February 2011, respectively. In silvopastoral system, there are influences of the tree component on most of the characteristics of the pasture according to the distance from the row of trees. The presence of trees in silvopastoral system promotes greater deposition of N via litter may contribute to long-term sustainability of the system. / O objetivo deste estudo foi avaliar a biomassa, teor de N da forragem e da serrapilheira, resposta morfofisiológica da planta, em diferentes distâncias das árvores dentro dos sistemas silvopastoris e comparar esse sistema com o sistema de monocultivo (a pleno sol) na Zona da Mata de PE. Os tratamentos experimentais consistiram na associação da gramínea Brachiaria decumbens Stapf. com as leguminosas sabiá (Mimosa caesalpiniifolia Benth) e gliricídia [Gliricidia sepium (Jacq.) Kunth ex Walp] e mais dois tratamentos da B. decumbens em monocultivo sendo um a gramínea exclusiva sem adubação nitrogenada e outro formado pela gramínea adubada com 60 kg N/ha/ano. As amostragens foram realizadas na fila dupla de leguminosas arbóreas e em quatro diferentes pontos que se distanciavam da fileira dupla das leguminosas, ou seja, 1,375; 2,75; 4,125 e 5,5 m, e de forma aleatória em sistema de monocultivo. Foram avaliadas as seguintes variáveis: porcentagem de material morto e de folha, altura do dossel, Índice de Área Foliar (IAF), índice SPAD, massa de forragem, teor de N na Brachiaria decumbens, teor de N da serrapilheira. Os teores de N na forragem foram menores a 5,5 m de distância das árvores, variando entre os diferentes períodos de avaliação entre 1 a 1,63%. A maior massa de forragem foi de 8376 kg MS/ha verificada a 4,125 m das árvores. Nos diferentes períodos de avaliação o contraste mostra (P=0,0001) que em sistemas silvipastoril o teor de N na Brachiaria decumbens foi maior, quando comparado ao monocultivo com e sem adubação, com exceção dos meses de setembro de 2010 e fevereiro de 2011 onde a Brachiaria decumbens em monocultivo, recebendo adubação nitrogenada, apresentou maiores teores de N, sendo de 1,02 e 1,7%, respectivamente, quando comparado ao sistema silvipastoril apenas no tratamento da gramínea consorciada com o Sabiá, que apresentou 0,9 e 1,64 % nos meses de setembro de 2010 e fevereiro de 2011, respectivamente. O menor teor de N na serrapilheira observado em sistema silvipastoril foi ao mês de maio de 2011, onde tanto o consórcio com a Gliricidia quanto a Sabiá em Ssp apresentaram 1% no teor de N na serrapilheira. Em sistema silvipastoril há influência do componente arbóreo sobre a maioria das características do pasto, conforme o distanciamento da fileira das árvores. A presença de árvores em sistema silvipastoril promove uma maior deposição de N via serrapilheira, podendo, a longo prazo contribuir para sustentabilidade do sistema. A fração leve da matéria orgânica, em monocultivo, foi menor em 62, 68 e 53% da observada em sistema silvipastoril para as profundidades 0-10, 10-20 e 20-40 cm, respectivamente.

Canals surrounding the Everglades carry enriched and polluted water high in minerals and nutrients. These enriched waters impact adjacent marsh habitats, altering flora and fauna species and abundance. Multiple studies have found gradients in nutrient levels as a function of distance from canals and emphasize the sensitivity of some organisms to these changes in water chemistry. Florida apple snails, Pomacea paludosa Say, are just one of many Everglades species sensitive to changes in water chemistry. They serve as an important staple in the diets of many Everglades predators including turtles, crayfish, limpkins and most importantly the endangered snail kite, Rostrahamus sociabilis which feeds almost exclusively on the apple snail. To examine potential effects of water chemistry on apple snail breeding patterns, we observed snail egg size, egg number per clutch, and carbon and nitrogen contents along water chemistry gradients and among snail breeding months at the Arthur R. Marshall Loxahatchee National Wildlife Refuge. Egg number per clutch and egg diameters were greatest in the most impacted zones and lowest in the pristine, interior zone. Carbon contents of eggs were highest in the interior and east side of the Refuge and lowest in the west side. Nitrogen contents of eggs were highest in the interior and west side of the Refuge, and lowest in the east side. Significant, albeit weak, positive trends were found between N content and egg diameter, C content and egg diameter, and between egg number per clutch and egg diameter, but only among specific zones and months. Results from this study suggest that snails in areas of the Refuge that are influenced by canal-water may produce greater numbers of apple snail offspring with greater egg diameters than those in less impacted areas. However, we do not know if this translates into higher hatchling success and survival.

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