Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2000. / Includes bibliographical references.

Orientador: Carlos Alexandre Costa Crusciol / Coorientador: Gustavo Pavan Mateus / Banca: Juliano Carlos Calonego / Banca: Denizart Bolonhezi / Resumo: O oeste paulista é caracterizado por solos de textura arenosa, alta demanda evapotranspirativa e períodos de défice hídrico durante a estação chuvosa. Além disso, nas reformas dos canaviais, é comum ocorrer preparo convencional do solo que aliado a prática de pousio no período chuvoso pode proporcionar problemas com erosão do solo, além de baixa produtividade e longevidade do canavial. O presente trabalho foi desenvolvido no Pólo Regional do Extremo Oeste, em Andradina-SP, com o objetivo de avaliar o efeito da sucessão de culturas combinado com diferentes sistemas de manejo do solo. O experimento foi instalado em esquema fatorial 3X6, consistindo nos tratamentos preparo do solo (convencional, preparo reduzido e plantio direto) e 6 espécies utilizadas em sucessão, sendo uma associação de Crotalaria juncea L. e Dolichos lablab L.; amendoim, soja, milho, sorgo sacarino e pousio. Antes de implantar as culturas, realizou a dessecação da cana com glifosate, na dose de 2160 g ha-1 60 dias após o corte. Foram analisados os sistemas radiculares das culturas de sucessão, pousio e cana de açúcar, componentes de produtividade e produtividade das culturas comerciais e cana, biomassa seca da parte aérea, teores foliares de nutrientes, teor de nutrientes no solo e resistência mecânica do solo a penetração. Não houve efeito do manejo do solo sobre o sistema radicular das culturas em rotação. O preparo de solo e a rotação de culturas não influenciaram os teores de nitrogênio no solo nas cultu... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The west of São Paulo is characterized by sandy soils, high evapotranspirative demand and periods of water deficit during the rainy season. In addition, in the sugarcane renew, conventional tillage is common, which, together with the rainin season, can lead to problems with soil erosion, as well as low productivity and longevity of the cane field. This work was developed at the "Polo Regional do Extremo Oeste" in Andradina, SP, Brazil, with the objective of evaluating the effect of crop succession combined with different soil management systems. The experiment was installed in a 3X6 factorial, consisting of soil tillage treatments (conventional, low-tillage and no-tillage) and 5 species used in succession, being an association of Crotalaria juncea L. and Dolichos lablab L .; peanuts, soybeans, corn, sorghum, and fallow. Before planting the crops, the sugar cane was eliminated with glyphosate at the dose of 2160 g ha-1 60 days after cutting. The root systems of crop rotation, fallow and sugarcane crops; yield and yield components of crop rotation and sugarcane crops; dry shoot biomass, nutrient leaf content, soil nutrient content and soil penetration resistance were analyzed. There was no effect of soil management on the root system of rotating crops. Soil tillage and crop rotation did not influence soil nitrogen contents in succession crops and in sugarcane. As a result, it observed the low productivity of succession cultures due to the water deficit in the vegetative and rep... (Complete abstract click electronic access below) / Mestre

Orientador: Newton La Scala Junior / Coorientador: Carolina Fernandes / Coorientador: Daniel De Bortoli Teixeira / Resumo: Concomitantemente ao desenvolvimento agrícola brasileiro surge a preocupação com os impactos ambientais causados pelo setor, dentre esses, as emissões de CO2 oriundas de práticas de cultivo e manejo dos solos nos sistemas produtivos. Neste estudo, objetivou-se investigar a variação temporal da emissão de CO2 e atributos físicos do solo sob influência do processo de reorganização das partículas do solo após as atividades de preparo do solo. O estudo foi conduzido em três áreas adjacentes medindo 10 × 3 m cada, nas quais foram conduzidos dois sistemas de preparo do solo: (i) enxada rotativa + grade niveladora convencional, representando um preparo intenso do solo (PI); (ii) grade aradora + niveladora, caracterizando um preparo reduzido (PR), e a terceira área envolvida no estudo foi mantida sem revolvimento do solo caracterizando o sistema semeadura direta (SD). Foram realizadas avaliações diárias da emissão de CO2 do solo (FCO2), temperatura e umidade do solo, distribuição de classes de poros, densidade do solo, resistência do solo à penetração, porosidade livre de água, diâmetro médio ponderado, índice de estabilidade de agregado, carbono orgânico total e carbono orgânico particulado, durante um período de 29 dias após o preparo do solo. No primeiro dia após preparo, a FCO2 foi 87% superior na parcela PI (3,86 µmol m-2 s-1) quando comparado a PR(2,06 µmol m-2 s-1) e 147% superior quando comparado a parcela sem distúrbio (1,56 µmol m-2 s -1). A densidade e a resistência do sol... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The development of the Brazilian agricultural sector necessarily implies a greater concern with diverse environmental impacts caused by the sector, among them the CO2 emissions from soil and crop management in the production systems. This study aimed to investigate the CO2 emission associated to physical properties in the short term after soil management submitted to different intensities. The study was conducted in three adjacent areas, measuring 10 × 3 m each, in which two soil tillage systems were performed: (i) rotary hoe + conventional harrow representing a much more intense soil tillage (PI); (ii) disc plowing + disc harrowing, characterizing a reduced soil tillage (PR), and in the third area was no-tillage (SD), without disturbance. They were carried out daily evaluations of soil CO2 emissions (FCO2), temperature and soil moisture, bulk density, soil resistance to penetration, water-free porosity, mean weight diameter, stability indices of soil aggregates, total organic carbon and particulate organic carbon, over a period of 29 days. On the first day after management, FCO2 was 87% higher in PI (3.86 μmol m-2 s-1) when compared to PR (2.06 μmol m-2 s-1) and was 147% higher when compared to area without disturbance (1.56 μmol m-2 s-1).The physical soil attributes: bulk density, resistance to penetration; showed lower variation from day 12 after soil management, this effect was considered in this study as a natural process of soil consolidation, and this process may also have influenced the temporal variation of soil CO2 emission. However, future studies involving a longer period of time are necessary in order to establish more concrete relationships. However, future studies involving a longer period of time are necessary to fortify the interrelations observed in this study. The distribution of pore cla... (Complete abstract click electronic access below) / Mestre

Orientador: Carolina Fernandes / Resumo: A escarificação somente na linha de plantio é um tipo de preparo mínimo do solo que vem sendo utilizado na reforma de canaviais, e o seu impacto sobre a qualidade física do solo necessita ser avaliado. O objetivo neste trabalho foi avaliar a qualidade física de Argissolo, submetido à escarificação para o plantio de cana-de-açúcar. Os tratamentos avaliados foram: escarificação do solo somente na linha de plantio (ELP) e escarificação em área total (EAT). O experimento foi realizado no município de Monte Alto, SP, próximos as coordenadas 21º 15’ S e 48º 25’ W, altitude média 735 m. Foram avaliadas quatro épocas de amostragem: após o preparo do solo com escarificação, após o plantio da cana-de-açúcar, seis meses após o plantio e após a colheita mecanizada da cana-de-açúcar. Amostras de solo foram coletadas nas camadas de 0,00-0,10 m, 0,10-0,20 m, 0,20-0,40 m e 0,40-0,60 m de profundidade em dois locais de amostragem (linha e entrelinha de plantio). Determinaram-se os teores de areia, silte e argila, e os atributos físicos: densidade do solo (Ds), resistência mecânica à penetração (RP), macroporosidade (MaP), microporosidade (MiP). A partir do conjunto de dados obtidos, realizou-se uma análise fatorial multivariada com extração dos fatores pelo método da análise de componentes principais. Dois fatores foram extraídos e explicaram 76% da variação total. O primeiro fator, responsável por 44 % da variância total pôde ser interpretado como a resposta da formação de microporosidade do... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Soil chiseling conducted only in the planting row is a type of minimal-disturbance soil management practice to prepare fields for planting of sugarcane plantations, and its impact on soil physical quality needs to be evaluated through agricultural experimentation. The objective of this study was to evaluate the physical quality of an Ultisol that was submitted to chiseling as part of sugarcane plantation management. The treatments consisted of soil chiseling only in the planting row (CPR), and chiseling in the total area of the soil of the plantation (CTA). The experiment was carried in Monte Alto, SP, near the coordinates 21º 15 'S and 48º 25' W, average altitude 735 m. Four sampling periods were evaluated. Four periods were evaluated: after soil chiseling, after sugarcane planting, six months after planting, and after mechanized sugarcane harvest. Soil samples were collected within and between planting rows in depths 0.00-0.10, 0.10-0.20, 0.20-0.40, and 0.40-0.60 m. Soil texture was determined along with the following soil physical indicators: bulk density (BD), mechanical penetration resistance (PR), total porosity (TP), macroporosity (MaP), microporosity (MiP). A multivariate factorial analysis was conducted with factor extraction done by the method of principal components analysis. Two extracted factors explained 76% of the total variation. The first factor responsible for 44% of the total variance could be interpreted as the response of soil microporosity formation infl... (Complete abstract click electronic access below) / Doutor

Submitted by DANIEL PEREIRA PINHEIRO (daniel_pinh@hotmail.com) on 2018-10-05T16:59:04Z No. of bitstreams: 1 TESE DEFINITIVO_04-10-2018 PRONTA IMPRIMIR.pdf: 1108350 bytes, checksum: 6cd437d78b4e85fca11fc1396fd5f9c0 (MD5) / Approved for entry into archive by Neli Silvia Pereira null (nelisps@fcav.unesp.br) on 2018-10-08T17:55:49Z (GMT) No. of bitstreams: 1 pinheiro_dp_dr_jabo.pdf: 1108350 bytes, checksum: 6cd437d78b4e85fca11fc1396fd5f9c0 (MD5) / Made available in DSpace on 2018-10-08T17:55:49Z (GMT). No. of bitstreams: 1 pinheiro_dp_dr_jabo.pdf: 1108350 bytes, checksum: 6cd437d78b4e85fca11fc1396fd5f9c0 (MD5) Previous issue date: 2018-07-11 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A escarificação somente na linha de plantio é um tipo de preparo mínimo do solo que vem sendo utilizado na reforma de canaviais, e o seu impacto sobre a qualidade física do solo necessita ser avaliado. O objetivo neste trabalho foi avaliar a qualidade física de Argissolo, submetido à escarificação para o plantio de cana-de-açúcar. Os tratamentos avaliados foram: escarificação do solo somente na linha de plantio (ELP) e escarificação em área total (EAT). O experimento foi realizado no município de Monte Alto, SP, próximos as coordenadas 21º 15’ S e 48º 25’ W, altitude média 735 m. Foram avaliadas quatro épocas de amostragem: após o preparo do solo com escarificação, após o plantio da cana-de-açúcar, seis meses após o plantio e após a colheita mecanizada da cana-de-açúcar. Amostras de solo foram coletadas nas camadas de 0,00-0,10 m, 0,10-0,20 m, 0,20-0,40 m e 0,40-0,60 m de profundidade em dois locais de amostragem (linha e entrelinha de plantio). Determinaram-se os teores de areia, silte e argila, e os atributos físicos: densidade do solo (Ds), resistência mecânica à penetração (RP), macroporosidade (MaP), microporosidade (MiP). A partir do conjunto de dados obtidos, realizou-se uma análise fatorial multivariada com extração dos fatores pelo método da análise de componentes principais. Dois fatores foram extraídos e explicaram 76% da variação total. O primeiro fator, responsável por 44 % da variância total pôde ser interpretado como a resposta da formação de microporosidade do solo influenciada pela natureza textural, uma vez que, as variáveis relevantes neste fator foram MiP, areia e argila. Esse fator representou o indicador intrínseco do solo. O segundo fator, responsável por 32 % da variância remanescente pôde ser interpretado como a resposta do processo de alteração na relação massa-volume do solo, uma vez que, as variáveis relevantes nesse fator foram MaP, Ds e RP. Esse fator remanescente, representou o indicador do manejo do solo. Após a extração dos fatores, com base nos valores de escores fatoriais obtidos, determinou-se um índice de qualidade física do solo (IQFS) que, conjuntamente com os dois fatores extraídos, auxiliaram na avaliação da qualidade física do solo. Após o preparo da área, as linhas de plantio submetidas à escarificação apresentaram qualidade física melhor que as entrelinhas de cultivo, em função do maior volume de poros e menor RP e Ds. Porém, o efeito benéfico da escarificação do solo não foi persistente em função do fenômeno da reconsolidação do solo, desaparecendo logo após o plantio e estendendo-se após a colheita da cana-de-açúcar, cujas linhas e entrelinhas de cultivo apresentaram qualidade física do solo semelhante para as duas áreas avaliadas. / Soil chiseling conducted only in the planting row is a type of minimal-disturbance soil management practice to prepare fields for planting of sugarcane plantations, and its impact on soil physical quality needs to be evaluated through agricultural experimentation. The objective of this study was to evaluate the physical quality of an Ultisol that was submitted to chiseling as part of sugarcane plantation management. The treatments consisted of soil chiseling only in the planting row (CPR), and chiseling in the total area of the soil of the plantation (CTA). The experiment was carried in Monte Alto, SP, near the coordinates 21º 15 'S and 48º 25' W, average altitude 735 m. Four sampling periods were evaluated. Four periods were evaluated: after soil chiseling, after sugarcane planting, six months after planting, and after mechanized sugarcane harvest. Soil samples were collected within and between planting rows in depths 0.00-0.10, 0.10-0.20, 0.20-0.40, and 0.40-0.60 m. Soil texture was determined along with the following soil physical indicators: bulk density (BD), mechanical penetration resistance (PR), total porosity (TP), macroporosity (MaP), microporosity (MiP). A multivariate factorial analysis was conducted with factor extraction done by the method of principal components analysis. Two extracted factors explained 76% of the total variation. The first factor responsible for 44% of the total variance could be interpreted as the response of soil microporosity formation influenced by the textural nature, since the relevant variables in this factor were MiP, sand and clay. This factor represented the soil intrinsic indicator. The second factor, responsible for 32% of the remaining variance, could be interpreted as the response of the alteration process in the soil mass-volume relationship, since the relevant variables in this factor were MaP, Ds and RP. This remaining factor represented the indicator of soil management.. After factor extraction and using the factorial scores, the index of soil physical quality was determined (SQI), which, together with two factor, aided in the evaluation of soil physical quality. After soil preparation, the planting rows that were submitted to chiseling had better soil physical quality than did the area between the rows that did not receive chiseling in site preparation due to greater pore volume and lower PR and BD. However, the beneficial effect of chiseling did not persist due to subsequent soil reconsolidation, and disappeared soon after the planting of sugarcane, and remained this way up to the post-harvest period wherein the areas within (CPR) and between (CTA) the planting rows had equal soil physical quality. / 2014/14490-2

Although most vegetables are grown using conventional tillage (CT) practices, no-tillage (NT) is becoming more prominent in vegetable production due to growers gaining more understanding of the economic and ecological benefits associated with the NT production system. Nitrogen (N) fertility management in NT systems is important to maximize yield productivity, but there is little available information on N fertilizer recommendations for vegetable crops grown in this production system. Therefore, two field studies were conducted at a grower location in southern Illinois to determine the effect of N application rates in NT zucchini squash and cucumber production following the herbicide burn-down of a wheat cover crop in early spring. Results indicated that the maximum total squash fruit yield was achieved when 30 to 120 lb N/acre was sidedress applied [or a range of 125 to 210 lb total N (pre-plant, soil, and applied N)/acre]. Although squash plant growth was maximized when 180 lb N/acre was sidedressed (or a range of 264 to 273 lb total N/acre), the overall yield was less compared to the 30 to 120 lb N/acre rates. Cucumber results indicated that maximum total fruit yield was achieved again at 30 to 120 lb N/acre sidedress rates (or a total N rate range of 114 to 208 lb/acre). Cucumber plant growth was maximized at a sidedress application of 120 to 180 lb N/acre, although yield decreased at the 180 lb N/acre sidedress rate (or 260 to 270 lb total N/acre). It appears that if cucurbit vegetables have high amounts of N available in the soil through over application of N fertilizer, the excess N will be used for plant vegetative growth rather than for fruit production. These studies indicated that when too much N is applied in both NT cucumbers and zucchini squash, these high N rates will stimulate vegetative growth (as indicated by high plant vigor and leaf chlorophyll content) while reducing fruit yields.

AN ABSTRACT OF THE THESIS OF Taylor J. Sievers, for the Master of Science degree in Plant, Soil, and Agricultural Systems, presented on May 13, 2016, at Southern Illinois University Carbondale. TITLE: COVER CROP CHARACTERISITICS AND IMPACTS ON AGRONOMIC SYSTEMS IN SOUTHERN ILLINOIS MAJOR PROFESSOR: Dr. Rachel L. Cook Midwestern farmers face the dual challenge of increasing crop production while reducing environmental impacts. Best management practices to decrease nutrient and soil loss in agronomic systems has fueled the resurgence of the cover cropping practice, but many growers are uncertain about the effects that different cover crop species may have in their fields or how combinations of tillage and cover crops may influence yields or soil characteristics. Different cover crop characteristics, such as above and belowground biomass production, nitrogen content, and decomposition may affect both soils and crop yields. Field experiments were conducted across two sites in southern Illinois from 2013 to 2015 to study characteristics of cover crops and the impact of cover crops and tillage on soils, nutrient availability, and agronomic field crop performance. Specifically, these studies 1) determine the effects of cover crops on soil nitrogen, 2) quantify above and belowground biomass production of cover crops, 3) quantify the grain yield and belowground biomass of the following crops of corn (Zea mays L.) and soybeans (Glycine max L. Merr.), and 4) evaluate cover crop decomposition and nutrient release of a leguminous and non-leguminous species. In both field sites, Hairy vetch (Vicia villosa Roth) treatments produced the most biomass and accumulated the most nitrogen of all cover crop treatments. Cover crop establishment was a problem for the 2014−2015 field season. Cover crops, for the most part, did not have an influence on corn or soybean grain yields, except that corn following Hairy vetch treatments tended to be higher in grain yields than corn following Annual ryegrass treatments. Soybeans following Annual ryegrass treatments tended to be higher in grain yield than soybeans following Canola treatments. Root biomass production was higher for cover cropped plots than non-cover cropped plots (weed root biomass), and corn or soybean root biomass was more affected by tillage practices rather than the main effect of cover crop. Tilled treatments were typically higher in soil nitrate and total inorganic nitrogen compared to No-till treatments, and Annual ryegrass treatments were consistently lower in soil nitrogen compared to other cover crop treatments. Hairy vetch and cereal rye (Secale cereale L.) decomposition and nutrient release was monitored over a 16 week period, with litterbag and intact root core collections at 2, 4, 6, 8, 12, and 16 weeks. Decomposition and nitrogen release data were fit to a single exponential decay model with an asymptote. Cereal rye aboveground (k = 0.14) and belowground (k = 0.19) biomass decomposed more gradually compared to hairy vetch aboveground (k = 0.45) and belowground (k = 0.68) biomass. The same trend developed for nitrogen release with cereal rye aboveground (k = 0.07) and belowground (k = 0.19) biomass releasing nitrogen slower and more gradually compared to hairy vetch aboveground (k = 0.61) and belowground (k = 0.61) biomass. Most of the hairy vetch nitrogen was released around Week 2, but the corn crop did not reach the V6 growth stage until Week 8, therefore cover crop nitrogen release and cash crop uptake may have not been synchronized. Plant Root Simulator™ ion exchange resin membrane probes also captured significantly more nitrogen in hairy vetch plots compared to cereal rye plots at weeks 2, 4, 6, 8, and 12, which indicates that hairy vetch could increase the readily plant available total nitrogen (nitrate + ammonium) in the soil throughout the bulk of cover crop decomposition. Farmers should decrease the time between cover crop termination and cash crop planting in order to increase the likelihood of crop synchrony. This research will help farmers develop better management practices regarding inclusion of cover crops into traditional agronomic production systems.

Corn (Zea mays L.) and soybean (Glycine max L.) production in the Midwest US can result in significant nutrient leaching to groundwater and surface waters, which contributes to eutrophication and hypoxia in the Gulf of Mexico. A promising strategy to control nutrient leaching and sediment runoff loss during winter fallow period is the use of cover crops (CCs). In southern Illinois, CCs are not widely adopted by farmers due to economic constraints and the lack of scientific data that supports benefits of incorporating CCs into the corn-soybean rotation. Therefore, this doctoral dissertation addresses the critical question of the feasibility of the use of CCs in southern Illinois and is divided into three overarching research studies with different objectives divided into six research chapters. Research study 1 was a field experiment conducted from 2013 to 2017 to examine the effect of CCs (CC vs noCC) under two tillage systems [(no-tillage (NT) and conventional tillage (CT)] on aboveground plant attributes [dry matter yield, C:N ratio and nitrogen uptake (N uptake)], crop yields, available soil N content and N leaching in the vadose zone. The experimental layout was a randomized design with three rotations including corn-noCC-soybean-noCC [CncSnc], corn-cereal rye (Secale cereale L.) –soybean-hairy vetch (Vicia villosa R.) [CcrShv], and corn-cereal rye-soybean-oats+radish (Avena sativa L. + Raphanus sativus L.) [CcrSor] and two tillage systems. Soil samples collected after corn or soybean harvest and CC termination were analyzed for standard soil fertility parameters. Pan lysimeters installed below the ‘A’ horizon with depth varying from 22 to 30 cm were used for measuring soil solution nutrient concentration on weekly or biweekly basis depending on the precipitation. In NT system, the corn yield was 14% greater with CcrShv compared to CncSnc, whereas no significant difference existed in corn yield due to CC treatments within CT. Both CC treatments under NT reduced soybean yield by 24 to 27% compared to noCC. The rotations CcrShv and CcrSor with hairy vetch and oats+radish as preceding CCs resulted in 89% (37.73 vs 19.96 kg ha-1) and 68% (33.46 vs 19.96 kg ha-1) more nitrate-N (NO3-N) leaching than the CncSnc during cash crop season 2015. During the CC season in spring 2016, cereal rye CC in CcrShv and CcrSor reduced the NO3-N leaching by 84% (0.68 kg ha-1) and 78% (0.63 kg ha-1) compared to the CncSnc, respectively, under the CT system. Overall, our results indicated that the CT system had greater N leaching losses compared to NT system due to higher N availability in the tilled soil profile. The goal of the second research study was to understand the mechanisms of N cycling by CCs. Therefore, we applied 15N labeled urea fertilizer (9.2% atom) to corn that followed hairy vetch and noCC in May 2017 to evaluate the contribution of fertilizer and soil organic matter to N leaching and quantify the 15N content of surface runoff after storm events. During the 2017 corn season, repeated soil samples were collected and analyzed for 15N fertilizer recovery in soil at three depths. 15N recovery was higher in the corn that had hairy vetch as the preceding CC than the corn that had noCC by 13.13 and 3.68 kg ha-1 on soil sampling events of 7 and 21 days after planting of corn, respectively, at the depth 15-30 cm. Overall, the cumulative loss of 15NO3-N during corn season 2017 was <2% of the applied fertilizer. The contribution of NO3-N from soil organic matter to leaching was 61% higher for the corn rotation with hairy vetch CC compared to corn rotation with noCC (1.12 vs 0.69 kg ha-1). Research study 3 evaluated the effects of CCs (cereal rye and hairy vetch) and topography (shoulder, backslope, footslope) on corn-soybean production, soil and water quality, nutrient and sediment export in agricultural headwater streams in a paired-watershed experimental design. The crop rotation followed in the CC-watershed was corn-cereal rye-soybean-hairy vetch whereas the rotation in the noCC watershed was corn-noCC-soybean-noCC. Use of hairy vetch CC increased N uptake at shoulder, backslope and footslope positions by 110.90, 85.02, and 44.89 kg ha-1, respectively, when compared to noCC treatment. The corn yield at the shoulder position was increased by 69% in CC-watershed compared to noCC watershed in 2017 likely by providing large N additions following decomposition. Cereal rye increased soybean yield by 17% and 8% at the shoulder and backslope position, respectively in 2016. Additionally, the effects of topography and CCs on soil N levels and N leaching in the watersheds were also evaluated. The NO3-N concentrations measured using suction cup lysimeters in CC-watershed were reduced by 2.54 mg L-1 (67%) when compared to noCC watershed. During the hairy vetch CC season, the reduction in NO3-N concentrations in soil solution was only seen at the footslope position. The excessive N at footslope positions may have been immobilized or denitrified due to soil waterlogging from higher water availability at the footslope. Forty-two and 18 storm events were collected during a 4-yr calibration period and CC-treatment period, respectively. Predictive regression equations developed from the calibration period were used for calculating TSS, NO3-N, NH4-N, and DRP losses of surface runoff for the CC-treatment watershed. The CCs reduced TSS and discharge by 33% and 34%, respectively in the CC-watershed during the treatment period. However, EMCs for NO3-N, NH4-N, and DRP did not decrease. Overall, CCs are a recommended conservation practice for farmers who want to enhance the long term profitability of their production systems, while building soil health and protecting downstream water quality. The CCs have the potential to reduce nutrient leaching, peak/total discharge, improve soil quality and crop yields. However, reduction in leaching will depend on the type of CC (legume vs non-legume crops) used in rotation, the time of termination of CCs, cover crop establishment and number of years under CCs. Synchronizing N availability from CCs to N uptake by cash crop is important for reducing nitrate leaching and increasing crop yields.

Made available in DSpace on 2014-06-11T19:31:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-01Bitstream added on 2014-06-13T19:41:53Z : No. of bitstreams: 1 fernandes_jc_dr_botfca.pdf: 1115073 bytes, checksum: 2801ee5f0b4afe076eb6fd7a690f282d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O girassol é uma oleaginosa de reconhecida importância na alimentação animal, humana, sendo, atualmente, uma das principais matérias-prima para produção de biocombustível. Existem poucos estudos relacionados aos sistemas de manejo do solo adotados para esta cultura. Objetivou-se no presente trabalho quantificar e analisar os efeitos dos sistemas de manejo nos atributos físicos e químicos de um Nitossolo Vermelho Distroférrico (NVdf), após a colheita do girassol, em uma área cultivada durante 11 anos sob o sistema de semeadura direta, e identificar a velocidade na operação de semeadura que permite o melhor desenvolvimento do girassol. O experimento foi instalado na Fazenda Experimental do Lageado, pertencente à Faculdade de Ciências Agronômicas da UNESP, localizada no município de Botucatu-SP. O delineamento experimental foi em blocos ao acaso, seguindo o esquema de parcela subdividida, com quatro repetições. Os tratamentos efetuados nas parcelas foram: os sistemas de manejo do solo (semeadura direta com mecanismo sulcador tipo haste- SDh; semeadura direta com mecanismo sulcador tipo disco duplo-SDd; cultivo reduzido-CR e cultivo convencional-CC). Nas subparcelas, as velocidades utilizadas para a semeadura foram de 3; 5; 6 e 8 km h-1. Amostras de solo foram coletadas na camada superficial, após a colheita do girassol e analisou-se a textura do solo, densidades, porosidade, diâmetro médio ponderado, percentagem de agregados, resistência do solo à penetração e análise química do solo. Para o desempenho operacional dos equipamentos de preparos do solo e semeadura, foram analisadas as seguintes variáveis: velocidade de semeadura, patinagem das rodas motrizes, força média de tração na barra, resistência específica operacional, potência média de tração na barra, consumo horário e operacional de combustível, capacidade de campo teórica e área de solo... / The sunflower is an oleaginous plant of recognized importance in the animal and human feeding, being, at present, one of the main raw materials for bio-fuels production. There are few researches to the soil management systems for this crop. It was objectified in the present work to quantify and to analyze the effect of the management systems in the physical and chemical attributes of a Paleudult, after the harvest of the sunflower, in an area cultivated during 11 years under the system of direct sowing, identify the speed in the sowing operation that allows the best development in the productivity of the sunflower. The experiment was installed in “UNESP – São Paulo State University”, in the Experimental Farm of the Lageado of the Agronomic Sciences College- Botucatu-SP. The experimental was in randomized block design in split plot, with four repetitions. The effected treatments in the plots were: the soil management systems (no-till using furrow opener with mechanism type rod-SDh; no-till using furrow opener with mechanism type double disk-SDd record; minimum tillage-CR and conventional tillage-CC). In the sub plots, the used speeds for the sowing were 3; 5; 6 and 8 km h-1. Soil samples were collected in the surface layer, after the harvest of sunflower and analyzed to soil texture, density, porosity, mean weight diameter, percentage of aggregates, soil resistance to penetration and soil chemistry analysis. For the operational performance of equipment for soil preparation and seeding, were analyzed the following variables: speed of sowing, skating wheels driving, the average tensile strength in the bar, resistance specific operational, average power of the traction bar, time consumption and operational fuel, field capacity and theoretical area of soil mobilized. The variables of the culture of sunflower were evaluated: plant population, longitudinal distribution of plants... (Complete abstract click electronic access below)