No abstract

(4) RESUMO Dados de perdas de água e solo obtidos em estudos de erosão hídrica são necessários nos planos de conservação do solo. Mesmo com o advento do sistema de semeadura direta, difundido no Brasil a partir dos anos de 1970, ainda se fazem necessárias práticas conservacionistas para o efetivo controle da erosão hídrica, como o uso do cultivo em contorno e o terraceamento, especialmente em regiões com altos volumes de chuva. Outra opção para o controle da erosão é o uso de culturas protecionistas do solo. O objetivo deste trabalho consistiu em quantificar as perdas de água e solo por erosão hídrica, em um solo cultivado com soja e milho sob semeadura direta, nas direções da pendente e em contorno ao declive. O experimento foi realizado em um Cambissolo Húmico alumínico léptico, no período de 2010-2011, sob a aplicação de quatro testes de chuva simulada. Estudaram-se cinco tratamentos, com duas repetições, sendo eles: semeadura de soja no sentido do declive (SD); semeadura de soja no sentido da curva de nível (SC); semeadura de milho no sentido do declive (MD); semeadura de milho no sentido da curva de nível (MC); e testemunha -solo sem cultivo e descoberto (T). Os cultivos foram implantados sobre resíduo cultural de trigo, no sistema de semeadura direta. A semeadura da soja em contorno foi mais eficaz no controle das perdas de solo do que a semeadura dessa no sentido do declive. A cultura do milho foi mais eficaz no controle das perdas de solo do que a soja, independentemente da forma de semeadura, e ambas foram mais eficazes do que a testemunha. As perdas de água

SUMMARYWater erosion is the major cause of soil and water losses and the main factor of degradation of agricultural areas. The objective of this work was to quantify pluvial water erosion from an untilled soil with crop rows along the contour, in 2009 and 2010, on a Humic Dystrupept, with the following treatments: a) maize monoculture; b) soybean monoculture; c) common bean monoculture; d) intercropped maize and bean, exposed to four simulated rainfall tests of on hour at controlled intensity (64 mm h -1 ). The first test was applied 18 days after sowing and the others; 39, 75 and 120 days after the first test. The crop type influenced soil loss through water erosion in the simulated rainfall tests 3 and 4; soybean was most effective in erosion control in test 3, however, in test 4, maize was more effective. Water loss was influenced by the crop type in test 3 only, where maize and soybean were equally effective, with less runoff than from the other crops. The soil loss rate varied during the runoff sampling period in different ways, demonstrating a positive linear relationship between soil and water loss, in the different rainfall tests.Index terms: water losses, soil losses, simulated rainfall. RESUMO: EROSÃO HÍDRICA EM SOLO NÃO PREPARADO CULTIVADO EM CONTORNO COM USO DE SISTEMAS DE CULTIVO SOLTEIRO E EM CONSÓRCIO

Water erosion in soil is influenced by several factors, including rain, relief, cover, and management and conservation practices. Also, erosion is affected by pig slurry (PS) applied to the soil as a fertilizer. The objectives of this research were i): to evaluate water erosion in a Humic Cambisol cultivated with Zea mays L., Avena strigosa, Glycyne max L., and Raphanus sativus in rotation after PS dispersal under different tillage treatments, namely: no-tillage (NT), minimum tillage (MT), rotation tillage (RT) and conventional tillage (CT) , and ii): to compare erosion before and after PS application in a single dose of 50 m3 ha-1 in each crop, soon after the germination of the crops. NT had lower soil and water loss, which were reduced by 81 and 13%, respectively, in relation to CT. Differences in soil and water losses were lower between MT and RT, than between other treatments. The contents of phosphorus (P) and potassium (K) in the superficial layers of the soil were higher under NT than under CT. The contents of P and K in the sediments were higher in the NT than in the CT treatment. Also, the contents of P and K were significantly higher in sediments than in water, especially under NT. The application of a single PS dose on the soil surface increased soil P and K contents and decreased water erosion compared to the 19-year historical series that preceded this research in different soil management systems without PS application.