Intervalo hídrico ótimo e compactação do solo com cultivo consorciado de milho e braquiária.

O cultivo consorciado entre a espécie forrageira e a cultura produtora de grãos garante a produção de forragem no outono-inverno, além de palha para cobertura do solo em sistema semeadura direta. O aporte de matéria seca radicular no perfil do solo possibilita a melhoria da qualidade estrutural do solo. Objetivou-se com este experimento verificar as alterações nos atributos físicos e físicohídricos do solo com o cultivo de milho solteiro e consorciado com Brachiaria brizantha. O experimento foi conduzido na Fazenda Experimental Lageado (UNESP, Botucatu-SP), entre os anos agrícolas de 2002/2003 e 2003/2004. Foram coletadas amostras com estrutura preservada de solo, por meio de anéis volumétricos, nas camadas de 0 a 20 e 20 a 40 cm de profundidade, em trincheiras abertas em parcelas cultivadas com milho e mantidas em pousio na entressafra, bem como em parcelas cultivadas com milho consorciado com B. brizantha na linha de semeadura, mantendo a forrageira para pastagem após a colheita do milho. A partir dessas amostras, foi avaliado o Intervalo Hídrico Ótimo (IHO), por meio de curvas de resistência à penetração e de retenção de água, em amostras com diferentes densidades do solo. O cultivo solteiro de milho na safra de verão é suficiente para melhorar as características físicas e estruturais do solo na camada de 0 a 20 cm. O cultivo de braquiária em consórcio com o milho por dois anos consecutivos melhora as condições físicas e estruturais do solo na camada de 20 a 40 cm, com redução da resistência mecânica à penetração e aumento da densidade crítica do solo

Manejo de espécies forrageiras em consórcio com milho safrinha.

O propósito deste documento é fornecer algumas informações sobre o cultivo consorciado de milho com espécies forrageiras dos gêneros Urochloa e Panicum, de forma a proporcionar maiores subsídios na tomada de decisão quanto à adoção deste sistema visando a sustentabilidade de sistemas produtivos de grãos e de carne/leite, pela utilização do componente forrageiro em duplo propósito para fornecer forragem no período de maior escassez de alimento e, ainda, viabilizar o SPD pelo resíduo depositado na superfície do solo.Editado por: Germani Concenço, Gessi Ceccon

Manejo de espécies forrageiras em consórcio com milho safrinha.

O propósito deste documento é fornecer algumas informações sobre o cultivo consorciado de milho com espécies forrageiras dos gêneros Urochloa e Panicum, de forma a proporcionar maiores subsídios na tomada de decisão quanto à adoção deste sistema visando a sustentabilidade de sistemas produtivos de grãos e de carne/leite, pela utilização do componente forrageiro em duplo propósito para fornecer forragem no período de maior escassez de alimento e, ainda, viabilizar o SPD pelo resíduo depositado na superfície do solo.Editado por: Germani Concenço, Gessi Ceccon

Evaluation of the recovery 15n-ammonium nitrate in capim-Marandu grass pasture and corn cultivated in a crop-livestock integration.

The study aimed at evaluating the total nitrogen accumulation and the nitrogen accumulated in the intercropping corn and B. brizantha evaluating the total nitrogen concentration from the fertilizer ammonium nitrate under different rates (15NH4NO3) applied in the forages plants after corn harvest, and the residual effect of this practice in the following corn crop in the next growing season

Physical fractions of soil organic matter as affected by cover crops and no-till system.

The objective of this study was to evaluate the effect of cover crops on total organic carbon and physical fractions of soil organic matter in soil under a no-tillage system and a conventional tillage system (CTS, one plowing and two disking)

Cover crops species as affecting soil aggregation, aggregate stability, organic carbon concentration and soil bulk density in different soil aggregate fractions.

The objectives of this study were to elucidate the effects of crop rotation with cover crop species in the soil aggregation, total organic carbon concentration in the whole soil and in the soil aggregates fractions and soil bulk density of the cultivated soil under no-tillage system and conventional tillage system (one plowing and two disking)

Evaluation of the recovery 15n-ammonium nitrate in capim-Marandu grass pasture and corn cultivated in a crop-livestock integration.

The study aimed at evaluating the total nitrogen accumulation and the nitrogen accumulated in the intercropping corn and B. brizantha evaluating the total nitrogen concentration from the fertilizer ammonium nitrate under different rates (15NH4NO3) applied in the forages plants after corn harvest, and the residual effect of this practice in the following corn crop in the next growing season

Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization.

The grain yield of upland rice under no-tillage has been unsatisfactory and one reason could be the nitrate/ammonium balance in the soil. Cover crops and nitrogen fertilization can be used to change the nitrate/ammonium relation in the soil and improve conditions for the development of upland rice in the no-tillage (NT) system. The aim was to study the effect of cover crops and nitrogen sources on grain yield of upland rice under no tillage. The study was carried out on the Fazenda Experimental Lageado, in Botucatu, State of São Paulo, Brazil, in an Oxisol area under no-tillage for six years. The experiment was arranged in a randomized block split-plot design with four replications. The plots consisted of six cover crop species (Brachiaria brizantha, B. decumbens, B. humidicola, B. ruziziensis, Pennisetum americanum, and Crotalaria spectabilis) and the split-plots of seven forms of N fertilizer management. Millet is the best cover crop to precede upland rice under NT. The best form of N application, as nitrate, is in split rates or total rate at topdressing or an ammonium source with or without a nitrification inhibitor, in split doses. When the cover crops C. spectabilis, B. brizantha, B. decumbens, B. humidicola, and B. ruziziensis preceded rice, they induced the highest grain yield when rice was fertilized with N as ammonium sulfate source + nitrification inhibitor in split rates or total dose at topdressing

Management impacts on soil organic matter of tropical soils.

Increased soil organic matter (SOM) improves the cation exchange capacity of tropical weathered soils, and liming is required to achieve high yields in these soils. Despite a decrease in SOM in the short term, liming may increase SOM with time by improving cation chemical bonds with soil colloids. Soil C may also be increased in high dry matter input cropping systems. We evaluated C changes in a Typic Rhodudalf as affected by four production systems with increasing residue inputs, with or without limestone or silicate. Soil use intensification by increasing the number of species in rotation as well as acidity remediation resulted in higher plant residue production. Introducing a green manure or a second crop in the system increased plant residue by 89% over fallow, but when a forage crop was used, plant residues more than doubled. Soil acidity amelioration increased plant residue deposition by 21% over the control. The introduction of a forage crop increased labile SOM and C contents in the particulate fraction, and lime or silicate application led to increases in the more stable SOM fraction. High amounts of plant residues (>70 Mg ha?1 in 5 yr) are effective in raising soil labile C, but the alleviation of soil acidity results in increased soil stable C irrespective of crop rotations in tropical weathered soils, and in this case plant residue deposition can be lower. Lime and silicate are equally effective in alleviating soil acidity and increasing soil C, probably due to the formation of cation bridges with soil colloids