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.

Made available in DSpace on 2016-03-07T19:20:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-09-08. Added 1 bitstream(s) on 2016-03-07T19:24:01Z : No. of bitstreams: 1 000859313.pdf: 21076207 bytes, checksum: a9c6ff7a00a20dda6fe0ac75d76184c4 (MD5) / O planejamento da sucessão de culturas aliada a cultivos de plantas de cobertura na entressafra e a descompactação mecânica são opções para minimizar a compactação na camada superficial do solo bem como proporcionar melhorias nos atributos do solo em sistema plantio direto (SPD), contribuindo para a sustentabilidade do sistema de produção. Assim, objetivou-se quantificar o efeito da descompactação mecânica do solo, no desenvolvimento e produtividade das plantas de cobertura na primavera em SPD, e também no crescimento e produtividade das culturas do arroz de terras altas e feijão de inverno em sucessão, além das alterações nos atributos químicos e físicos do solo, após cada cultivo das culturas anuais. O trabalho foi desenvolvido em Selvíria, MS em 2012/13 e 2013/14, em um Latossolo Vermelho de Cerrado, textura argilosa, com delineamento em blocos casualizados disposto em esquema fatorial 5x2 para o arroz e o feijão, com quatro repetições. Os tratamentos foram constituídos pela combinação de cinco plantas de cobertura (pousio (controle), Cajanus cajan, Crotalaria juncea, Urochloa ruziziensis e Pennisetum glaucum) com e sem escarificação mecânica do solo. A espécie de Pennisetum glaucum, independente do solo escarificado em SPD promoveu maior produtividade de matéria seca e acumulo de macronutrientes na parte aérea bem como maior persistência de resíduos vegetais; o solo escarificado em SPD e o cultivo anterior de Cajanus cajan proporcionaram maiores produtividades do arroz, no primeiro ano, todavia não influenciaram na produtividade do arroz no segundo ano; os cultivos antecessores de Crotalaria juncea e Pennisetum glaucum com escarificação, seguida de cultivo do arroz, proporcionaram incrementos na produtividade do feijão de inverno em sucessão; a entressafra de Pennisetum glaucum, Crotalaria juncea e Urochloa ruziziensis independentes da... / The planning succession allied cover crops in the off-season and sporadic mechanical decompression are options to minimize compaction soil surface under, as well as directly providing improvements in soil attributes in no-tillage system (NTS) deployed in the Savannah South Mato Grossense, advocating the sustainability of the production system. The objective was to evaluate the mechanical soil decompression, development and yield of cover crops in the spring in NTS, and also in the growth and yield of rice crop upland and common bean winter in succession, in addition to changes in chemical and physical attributes of the soil, after each cultivation of annual crops. The study was conducted in Selvíria, MS, in 2012/13 e 2013/14, in a Savannah South Mato Grossense, Oxisol, clayey, in a randomized block design arranged in a factorial design 5x2 for rice and common bean, with four replications. The treatments were a combination of five cover crops (fallow (control), Cajanus cajan, Crotalaria juncea, Pennisetum glaucum and Urochloa ruziziensis) with and without mechanical soil scarification. The species of Pennisetum glaucum, regardless of chiseling in NTS promoted greater dry matter yield and accumulation of macronutrients in the shoot as well as greater persistence of plant debris; the chiseling in NTS and the previous cropping Cajanus cajan provided higher yields of rice in the first year, but did not influence the rice yield in the second year; crops predecessors Crotalaria juncea and Pennisetum glaucum with scarification, followed by rice cultivation, provided increases in bean commun yield winter in succession; the off-Pennisetum glaucum, Crotalaria juncea and Urochloa ruziziensis independent of scarification Urochloa ruziziensis provided improvements more frequently in chemical attributes in the soil profile; the chiseling in NTS promoted greater porosity, and reduced the density and soil ...

Made available in DSpace on 2014-06-11T19:35:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-23Bitstream added on 2014-06-13T20:06:57Z : No. of bitstreams: 1 nakayama_ft_dr_ilha.pdf: 450316 bytes, checksum: 082c50b94e8da5be2360a3aaf96e6438 (MD5) / Universidade Estadual Paulista (UNESP) / A semeadura direta vem a cada ano ampliando sua área agrícola no cerrado e é imprescindível a manutenção da palhada para o sucesso desta tecnologia, devendo respectivamente atender à necessidade da cultura e promover a conservação do solo. Desta forma, este trabalho teve por objetivo avaliar os efeitos do consórcio de plantas utilizadas como coberturas vegetais no desenvolvimento e produtividade do algodoeiro bem como sua contribuição no condicionamento químico e físico do solo. O delineamento experimental empregado foi o de blocos ao acaso com quatro repetições no esquema fatorial 4x4 compreendendo os fatores: 1. Dicotiledôneas: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- “sem dicotiledônea”; 2. Monocotiledôneas: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- “sem monocotiledônea”. Foram realizadas avaliações de fitomassa seca e cobertura do solo nas coberturas vegetais e a influência na química e física do solo sendo analisadas a porosidade e resistência à penetração. Após o manejo da palhada foi semeada a cultura do algodão nas parcelas experimentais no qual foram avaliados os aspectos agronômicos da cultura. De acordo com os resultados obtidos, os consórcios entre monocotiledôneas e dicotiledôneas ou ao cultivo exclusivo de monocotiledöneas apresentam maiores percentagens de cobertura do solo se comparado ao cultivo isolado de dicotiledôneas. As maiores produtividades de fitomassa seca de plantas de cobertura foram proporcionadas pelo cultivo exclusivo de milheto e milheto associado ao guandu. A aveia preta proporcionou os menores valores de resistëncia a penetraçäo para as camadas superficiais do solo (0-15 e 15-30 cm); e os tratamentos dicotiledonares destacando- se o nabo forrageiro proporcionaram uma diminuição... / The practice of no tillage are expanding year why year in Cerrado and is essential the crop residues maintenance for success of this technology, respectively meet the needs of culture and promote soil conservation. The objective work was to evaluate the effects of the consortium of cover crops in the development and yield of cotton as well as his contribution to the chemical and physical conditioning of the soil. The experimental design was a randomized block design with four replicates in a 4x4 factorial factors including: 1. Dicotyledons: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- “no dicotyledons”; 2. Monocotyledons: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- “no monocotyledons”. Were evaluated vegetation cover, dry matter and the influence on chemical and physical soil being analyzed porosity and penetration resistance. After handling of the cover crop was sown cotton in the experimental plots in which we evaluated the agronomic aspects of culture. According to the results obtained, the consortium between monocots and dicots or monocots unique culture have higher percentages of soil coverage as compared to isolated from dicotyledons. The highest yield of dry biomass of cover crops were provided exclusively by the cultivation of Pennisetum glaucum and Pennisetum glaucum associated with Cajanus cajan. The Avena strigosa provided the lowest values of penetration resistance to the soil surface layers (0-15 and 15-30 cm) and dicots treatments distinguished Raphanus sativus provided a decrease in penetration resistance for layers 30 -45 and 45-60 cm. Pennisetum glaucum provided the highest values for total porosity and macroporosity in the 0-20 cm layer. Treatments isolated Raphanus sativus, Raphanus sativus associated Brachiaria ruziziensis or until Pennisetum glaucum sown in the month of July provided the highest yield for Deltaopal cotton in the Cerrado conditions

Made available in DSpace on 2014-06-11T19:35:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-22Bitstream added on 2014-06-13T19:24:49Z : No. of bitstreams: 1 arf_mv_dr_ilha.pdf: 1018011 bytes, checksum: 793b0adf130926442132cbb33f18d33f (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A produtividade média das culturas de milho, feijão e trigo no Brasil é considerada atualmente baixa, uma vez que, utilizando técnicas mais adequadas de cultivo, existe possibilidade, de em curto prazo, aumentar a produtividade dessas culturas. O objetivo deste trabalho foi estudar o efeito do consórcio de Brachiaria ruziziensis e Crotalaria spectabilis no desenvolvimento e produtividade do milho cultivado na primeira safra e, restos culturais dessas culturas e doses de nitrogênio no desenvolvimento e produtividade do feijoeiro “de inverno” e trigo em sistema plantio direto. Os experimentos foram conduzidos no município de Selvíria – MS, durante os anos agrícolas 2010/11 e 2011/12 em Latossolo Vermelho distrófico álico típico argiloso (20° 20’ S e 51° 24’ W, com altitude de 340 m). Foram estabelecidos 40 tratamentos com quatro repetições em blocos casualizados resultantes da combinação entre coberturas vegetais (milho, milho em consórico com Brachiaria ruziziensis, milho em consórcio com Crotalaria spectabilis, Brachiaria ruziziensis e Crotalaria spectabilis) e doses de N (0, 40, 80 e 120 kg ha -1 – fonte Ureia) nas culturas de feijão e trigo de inverno. Os efeitos de cobertura vegetal foram analisados pelo teste de Tukey e de dose pela análise de regressão. Os consórcios não interferiram no desenvolvimento e produtividade da cultura do milho; tanto o feijão quanto o trigo apresentaram resposta linear à adubação nitrogenada em ambos os anos agrícolas; o feijoeiro quando semeado sobre restos culturais de B. ruziziensis e C. spectabilis e o trigo sobre restos culturais de B. ruziziensis e milho, apresentaram maiores produtividades / The average productivity of maize, common bean and wheat in Brazil is currently considered low, since using more appropriate cultivation techniques, there is possibility of short-term, increase the productivity of these crops. The aim of this work was to study the effect of the consortium Brachiaria ruziziensis and Crotalaria spectabilis in the development and productivity of maize grown in the first crop and crop residues of these crops and nitrogen levels in the development and productivity of winter common bean and wheat in no tillage. The experiments were conducted in Selvíria - MS, during the years 2010/11 and 2011/12 in an alic typical clayey Oxisol (20 ° 20 'S and 51 ° 24' W, with an altitude of 340 m). We established 40 treatments with four replications in a randomized block design resulting from the combination of cover crops (corn, corn consorptium with Brachiaria ruziziensis, maize intercropped with Crotalaria spectabilis and Crotalaria spectabilis and Brachiaria ruziziensis) and N rates (0, 40, 80 and 120 kg ha-1 - source Urea) in crops of winter common bean and wheat. The effects of vegetation were analyzed by Tukey test and N doses by regression analysis. Consortia not interfere with the development and productivity of maize, both the corn and the wheat showed linear response to nitrogen fertilization in both years; the common corn when sown over residue of B. ruziziensis and C. spectabilis and wheat crop over B. ruziziensis and maize, showed greater productivity

Made available in DSpace on 2018-07-27T17:13:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-08-28. Added 1 bitstream(s) on 2018-07-27T17:16:38Z : No. of bitstreams: 1 000888008.pdf: 1516512 bytes, checksum: c2886eec72130443d7b85dc6efbd87dd (MD5) / A aplicação de práticas conservacionistas visa não só a manutenção e/ou melhoria da qualidade do solo, mas também minimizar significativos impactos ocasionados ao ambiente. O objetivo deste trabalho foi verificar a influência da decomposição de plantas de cobertura no desenvolvimento e produtividade da cultura da soja e milho em sucessão, na região do Cerrado. O experimento foi conduzido nos anos agrícolas de 2010/11 e 2011/12, nas áreas de pesquisa da Fundação Chapadão em Chapadão do Sul -MS, 18° 41' S e 52° 40' W, sendo implantadas com um delineamento em blocos ao acaso, com oito tratamentos e quatro repetições. Os tratamentos foram assim constituídos: 1- milho (Zea mays); 2- milho (Zea mays) + Urochloa ruziziensis; 3 - sorgo (Sorghum bicolor); 4 - Crotalaria spectabilis; 5 - Urochloa bryzantha; 6 - nabo forrageiro (Raphanus sativus) L.; 7 - milheto (Pennisetum americanum) e 8 - pousio. O milho em cultivo solteiro ou em consórcio com U. ruziziensis propiciam satisfatória cobertura, pela manutenção de palhada sobre a superfície do solo; os restos culturais de Raphanus sativus e U. bryzantha proporcionaram maior incremento de produtividade na cultura do milho cultivado na primeira safra na região do Cerrado; os restos culturais de milho, C. spectabilis e Sorghum bicolor proporcionaram maior incremento de produtividade na cultura da soja de verão / The application of conservation practices aims not only the maintenance and / or improvement of soil quality, as well as the organization and the occupation of the productive areas of the landscape in order to ensure the establishment of the main ecological and hydrological processes and minimize significant impacts caused to the environment . The objective of this study was to evaluate the effect of cover crops grown in the off season and in the development of cultivated maize grain yield in the first crop and soybean tillage system in the Cerrado region. The experiment was carried out in 2010/11 and 2011/12 crop years the Foundation of the experimental area for the Support of Agricultural Research of Plain, located in the municipality of South Chapadão, State of Mato Grosso do Sul, with an altitude of 810 m. The experimental design was a randomized block design with four replications and seven treatments constituted as follows: 1- Zea mays; 2- Zea mays + Urochloa ruziziensis; 3 - Sorghum bicolor; 4 - Crotalaria spectabilis; 5 - U. bryzantha; 6 - Raphanus sativus L., 7 - Pennisetum americanum and 8 - fallow. Corn in single or in consortium with Urochloa ruziziensis cultivation becomes spoiled by cover crops for Direct Planting System, due to its good maintenance of straw on the soil surface; cultural remains of forage turnip and Urochloa bryzantha provided productivity increase in the cultivated maize in the first season in the Cerrado region; the Corn debris, Crotalaria spectabilis and sorghum provided productivity increase in soybean of summer

Orientador: Orivaldo Arf / Co-orientador: Marlene Cristina Alves / Banca: Elcio Hiroyoshi Yano / Banca: Edson Lazarini / Banca: Pedro Marques da Silveira / Banca: Luis Fernando Stone / Resumo: O planejamento da sucessão de culturas aliada a cultivos de plantas de cobertura na entressafra e a descompactação mecânica são opções para minimizar a compactação na camada superficial do solo bem como proporcionar melhorias nos atributos do solo em sistema plantio direto (SPD), contribuindo para a sustentabilidade do sistema de produção. Assim, objetivou-se quantificar o efeito da descompactação mecânica do solo, no desenvolvimento e produtividade das plantas de cobertura na primavera em SPD, e também no crescimento e produtividade das culturas do arroz de terras altas e feijão "de inverno" em sucessão, além das alterações nos atributos químicos e físicos do solo, após cada cultivo das culturas anuais. O trabalho foi desenvolvido em Selvíria, MS em 2012/13 e 2013/14, em um Latossolo Vermelho de Cerrado, textura argilosa, com delineamento em blocos casualizados disposto em esquema fatorial 5x2 para o arroz e o feijão, com quatro repetições. Os tratamentos foram constituídos pela combinação de cinco plantas de cobertura (pousio (controle), Cajanus cajan, Crotalaria juncea, Urochloa ruziziensis e Pennisetum glaucum) com e sem escarificação mecânica do solo. A espécie de Pennisetum glaucum, independente do solo escarificado em SPD promoveu maior produtividade de matéria seca e acumulo de macronutrientes na parte aérea bem como maior persistência de resíduos vegetais; o solo escarificado em SPD e o cultivo anterior de Cajanus cajan proporcionaram maiores produtividades do arroz, no primeiro ano, todavia não influenciaram na produtividade do arroz no segundo ano; os cultivos antecessores de Crotalaria juncea e Pennisetum glaucum com escarificação, seguida de cultivo do arroz, proporcionaram incrementos na produtividade do feijão "de inverno" em sucessão; a entressafra de Pennisetum glaucum, Crotalaria juncea e Urochloa ruziziensis independentes da... / Abstract: The planning succession allied cover crops in the off-season and sporadic mechanical decompression are options to minimize compaction soil surface under, as well as directly providing improvements in soil attributes in no-tillage system (NTS) deployed in the Savannah South Mato Grossense, advocating the sustainability of the production system. The objective was to evaluate the mechanical soil decompression, development and yield of cover crops in the spring in NTS, and also in the growth and yield of rice crop upland and common bean "winter" in succession, in addition to changes in chemical and physical attributes of the soil, after each cultivation of annual crops. The study was conducted in Selvíria, MS, in 2012/13 e 2013/14, in a Savannah South Mato Grossense, Oxisol, clayey, in a randomized block design arranged in a factorial design 5x2 for rice and common bean, with four replications. The treatments were a combination of five cover crops (fallow (control), Cajanus cajan, Crotalaria juncea, Pennisetum glaucum and Urochloa ruziziensis) with and without mechanical soil scarification. The species of Pennisetum glaucum, regardless of chiseling in NTS promoted greater dry matter yield and accumulation of macronutrients in the shoot as well as greater persistence of plant debris; the chiseling in NTS and the previous cropping Cajanus cajan provided higher yields of rice in the first year, but did not influence the rice yield in the second year; crops predecessors Crotalaria juncea and Pennisetum glaucum with scarification, followed by rice cultivation, provided increases in bean commun yield "winter" in succession; the off-Pennisetum glaucum, Crotalaria juncea and Urochloa ruziziensis independent of scarification Urochloa ruziziensis provided improvements more frequently in chemical attributes in the soil profile; the chiseling in NTS promoted greater porosity, and reduced the density and soil ... / Doutor

Orientador: Enes Furlani Júnior / Banca: Salatiér Buzetti / Banca: Marco Eustaquio de Sa / Banca: José Carlos Cavichioli / Banca: Edivaldo Cia / Resumo: A semeadura direta vem a cada ano ampliando sua área agrícola no cerrado e é imprescindível a manutenção da palhada para o sucesso desta tecnologia, devendo respectivamente atender à necessidade da cultura e promover a conservação do solo. Desta forma, este trabalho teve por objetivo avaliar os efeitos do consórcio de plantas utilizadas como coberturas vegetais no desenvolvimento e produtividade do algodoeiro bem como sua contribuição no condicionamento químico e físico do solo. O delineamento experimental empregado foi o de blocos ao acaso com quatro repetições no esquema fatorial 4x4 compreendendo os fatores: 1. Dicotiledôneas: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- "sem dicotiledônea"; 2. Monocotiledôneas: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- "sem monocotiledônea". Foram realizadas avaliações de fitomassa seca e cobertura do solo nas coberturas vegetais e a influência na química e física do solo sendo analisadas a porosidade e resistência à penetração. Após o manejo da palhada foi semeada a cultura do algodão nas parcelas experimentais no qual foram avaliados os aspectos agronômicos da cultura. De acordo com os resultados obtidos, os consórcios entre monocotiledôneas e dicotiledôneas ou ao cultivo exclusivo de monocotiledöneas apresentam maiores percentagens de cobertura do solo se comparado ao cultivo isolado de dicotiledôneas. As maiores produtividades de fitomassa seca de plantas de cobertura foram proporcionadas pelo cultivo exclusivo de milheto e milheto associado ao guandu. A aveia preta proporcionou os menores valores de resistëncia a penetraçäo para as camadas superficiais do solo (0-15 e 15-30 cm); e os tratamentos dicotiledonares destacando- se o nabo forrageiro proporcionaram uma diminuição... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The practice of no tillage are expanding year why year in Cerrado and is essential the crop residues maintenance for success of this technology, respectively meet the needs of culture and promote soil conservation. The objective work was to evaluate the effects of the consortium of cover crops in the development and yield of cotton as well as his contribution to the chemical and physical conditioning of the soil. The experimental design was a randomized block design with four replicates in a 4x4 factorial factors including: 1. Dicotyledons: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- "no dicotyledons"; 2. Monocotyledons: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- "no monocotyledons". Were evaluated vegetation cover, dry matter and the influence on chemical and physical soil being analyzed porosity and penetration resistance. After handling of the cover crop was sown cotton in the experimental plots in which we evaluated the agronomic aspects of culture. According to the results obtained, the consortium between monocots and dicots or monocots unique culture have higher percentages of soil coverage as compared to isolated from dicotyledons. The highest yield of dry biomass of cover crops were provided exclusively by the cultivation of Pennisetum glaucum and Pennisetum glaucum associated with Cajanus cajan. The Avena strigosa provided the lowest values of penetration resistance to the soil surface layers (0-15 and 15-30 cm) and dicots treatments distinguished Raphanus sativus provided a decrease in penetration resistance for layers 30 -45 and 45-60 cm. Pennisetum glaucum provided the highest values for total porosity and macroporosity in the 0-20 cm layer. Treatments isolated Raphanus sativus, Raphanus sativus associated Brachiaria ruziziensis or until Pennisetum glaucum sown in the month of July provided the highest yield for Deltaopal cotton in the Cerrado conditions / Doutor

Master of Agribusiness / Department of Agricultural Economics / Jason S. Bergtold / Cover crops can be used as forage for cattle and other grazing animals. This research investigated the net returns of using cover crops for forage or grazing under four scenarios. These scenarios were: 1) a mixed crop and livestock producer who owns a herd of cattle and has both dry or pregnant cows and weaned calves available to graze corn stover and cover crops; 2) a crop farmer who purchases stocker cattle for the purpose of grazing the cover crop and corn stover; 3) a crop farmer who leases out a corn stover and cover crop field to a livestock producer (and who provides value-added services to the livestock producer for a fee); and 4) an integrated operation with crops and cattle where cover crops are not grown and hay is fed to cattle during the winter months. Each of these scenarios had different budgets, risks, and profit potentials. The research aimed to address the risks and profit potentials for each scenario. The stocking density was initially set at three cows and 31 steers for a period of 90 days, and alternatively, three cows and 25 steers for a period of 120 days. Two sets of cattle pricing data were used: the average historical prices from 1992 to 2011 and reported prices from a regional stockyard for the period of November 2016 to March 2017. The results showed that the initial stocking densities used for scenarios one and two were too low to provide profitable net returns regardless of pricing data used. Net returns for scenario three were also not profitable based on the services rendered and the management fee charged. Scenario four was profitable on one occasion. November steers with a 500 lb. average starting weight fed hay and concentrate for 120 days resulted in a positive net return of $375. A second analysis was done using stocking rates of 50, 75, or 100 steers to determine if increasing stocking density would result in a positive net return using only the 2016/2017 pricing data and only evaluating net returns on 2.0 and 2.5 lbs. of average daily gain. Positive net returns were achieved at various start weights and average daily gain rates at stocking rates of 75 and 100 animals. No positive net returns were realized at the stocking rate of 50 animals/100 acre field. The management fee charged for providing management services under scenario three was adjusted based on stocking densities to determine if a positive net return could be achieved at the set fee rate of $0.875/head/day. At that rate, no stocking rate resulted in a positive net return. Using the cost data, less the $900 field lease income, a breakeven pricing point for the management fee was determined for each stocking density and grazing duration within the scenario. Management of cost factors to achieve greater chances of profitability and additional research needs are discussed.

Intensive tillage and monoculture cropping practices reduce soil C accumulation hence increasing soil vulnerability to chemical, physical and biological degradation. This study focussed on enhancing biomass production of wheat and oat winter cover crops as a means of increasing C sequestration in the low organic C soils of the central part of Eastern Cape Province. The specific objectives were (i) to evaluate the short-term effects of no till and cereal-fallow based crop rotations on; soil organic matter related parameters, pH and electrical conductivity, (ii) soil bulk density, water retention and aggregate stability, (iii) soil microbial biomass C and N, mineralizable N, soil respiration, and dehydrogenase enzyme activity, (iv) grain yield, soil nutrient concentration (N, P and K) and their uptake by maize, and (v) to identify soil parameters with high sensitivity to tillage under maize-fallow-maize, maize-wheat-maize and maize-oat-maize rotational cover cropping practices. The experiment was laid out as a split-plot arrangement in a randomized complete block design with 4 replicates. Tillage treatments (CT and NT) were applied on the main plots which measured 8 × 18 m while crop rotation treatments were applied in the subplots which measured 8 × 6 m. The rotation treatments were maize-fallow-maize (MFM), maize-wheat-maize (MWM) and maize-oat-maize (MOM). Weed control in NT plots involved preplant application of glyphosate to control mainly the grass weeds while post emergence weed management was done using Atrazine (485 atrazine and 15 g l-1 triazines). Initial weed control in CT plots was achieved through ploughing to a depth of 20 cm followed by disking while post emergence weed iii management was done by hand hoeing. Soil parameters measured were; (i) particulate organic matter (POM), soil organic carbon (SOC), total nitrogen (TN), pH and electrical conductivity (EC), (ii) soil bulk density (b), moisture at field capacity (FC), aggregate mean weight diameter (MWD) determined by fast wetting (FW), slow wetting (SW), mechanical breakdown by shaking (MB) and the stability index (SI), (iii) soil microbial biomass C (MBC) and N (MBN), mineralizable N (MN), soil respiration (SR), and dehydrogenase enzyme activity (DHEA). No-till increased POM and TN compared to CT in Lenye and Burnshill, respectively. The MWM and the MOM rotations increased TN relative to the MFM rotation in Lenye. The MWM and MOM rotations enhanced SOC relative to MFM in all sampled soil depths at Burnshill and similar observations were made under MOM rotation in the 5-20 cm depth in Lenye. The MWM and MOM rotations tended to depress soil pH relative to the MFM rotation in both sampled soil depths in Lenye while NT reduced soil pH relative to CT on the surface soil layer in Burnshill. Soil EC and pH varied with depth across tillage practices but both parameters remained within the ideal range for successful crop production over the study period. Soil stability index (SI) and aggregate MWD determined by FW, SW and MB were higher in Lenye compared to Burnshill. The MOM rotation enhanced the SI relative to MFM and MWM rotations at both sites. Scanning electron microscope (SEM) showed that more organic C was incorporated into the soil under NT and MOM rotation compared to CT and MFM rotation which had few organic coatings on the soil particles. Microbial properties varied with plant biomass input as influenced by tillage and type of rotational cover crop at both sites. Like in other past studies, NT showed higher levels of MBC, MBN, NM and SR at the soil surface layer compared to CT in Burnshill. No till increased MN iv relative to CT in both sampled soil depths in Lenye and resulted in higher DHEA compared to CT in Burnshill. The MOM rotation increased MBC, MBN, MN relative to MFM rotation especially within surface soil layer. Similar observations were made with respect to MN and SR in both sampled soil layers at Lenye. By contrast, the DHEA was higher under the MFM relative to the MWM and MOM rotations in Lenye but similar under the MFM and MOM rotations in Burnshill. Maize grain yield was not affected by both tillage and crop rotations but varied with cropping season. Comparable grain yields observed under the two tillage practices with similar fertilizer application rates indicated the advantage of NT over CT in saving on labour costs in maize production without compromising yields. High plant biomass retention under NT relative to CT contributed to high soil N and P levels under the former compared to the latter tillage practice especially on soil surface layer at both study sites. Principal component analysis (PCA) revealed that soil chemical and biological parameters closely linked to organic matter, namely SOC, MN, MBC and MBN showed the highest sensitivity to tillage and crop rotation treatments. Soil aggregate MWD determined by SW and b were the physical parameters which were highly altered by agronomic management practice. The MWM and MOM rotations were clustered together and clearly separated from the MFM rotation and this observed trend only applied to the 0-5 and 5-20 cm depths in Lenye site only. No till, MWM and MOM rotations enhanced POM, SOC and TN relative to CT and MFM rotation suggesting these practices have greater potential to improve soil chemical properties compared to intensive tillage and maize monoculture based production practices. Reduced soil b under MOM rotation and improved SI under NT compared to MFM and CT, respectively v indicate that these practices have the potential to improve degraded soils. Although not significantly different, NT values for MBC, MBN, MN, SR and DHEA were higher compared to CT indicating the potential of the practice to improve soil biotic activity relative to conventional tillage practices. No till enhanced surface soil nitrate N and extractable P compared to CT at both sites revealing the long-term potential of NT in improving the supply of these essential plant nutrients compared to CT. Principal component analysis showed that SOC, MN, K, P, MBC, MBN, soil aggregate MWD determined by SW and b were the most sensitive parameters to tillage and crop rotations. Therefore, these parameters could constitute the minimum data set for assessments of the impact of selected CA practices on soil quality attributes.

<p>Cover cropping is an effective management practice for reducing nitrogen (N) losses to the environment from agriculture fields in the Midwest. Cereal rye (CR; <i>Secale cereale L</i>.) and hairy vetch (HV; <i>Vicia villosa Roth</i>) are two of the most common cover crop species grown in the region. However, limited cover crop adoption in the region is partly due to a dearth of knowledge addressing the effect of cover crops on nitrogen cycling and grain production within corn and soybean conservation cropping systems. The following studies were designed to address knowledge gaps in the current literature regarding the rate, quantity, and timing of cover crop residue C and N release; the fate of CR N following termination; and the effects of cover crops specifically on soybean growth, N assimilation, and yield. Data from this study revealed that growers should be aware that cover crop nutrient release may result in a “tug-of-war” between the soil microbiome and cash crops for soil inorganic-N. Additionally, we observed that CR N is used minimally by the subsequent crop; thus, growers should value CR N as a long-term benefit, such as building SOM. Finally, we found that added pressure from CR during early soybean growth may reduce soybean resilience, and in a wet year result in yield loss.</p>