ABSTRACT
O sistema de plantio direto (SPD) tem contribuído para melhorias nos solos agrícolas, dentre elas o aumento da concentração de nutrientes no solo. No entanto, tem se verificado que este aumento ocorre principalmente na camada superficial do solo, o que contribui para que ocorram perdas de nutrientes através de enxurradas, com danos econômicos e ambientais. Este trabalho avaliou a concentração total dos nutrientes potássio (K), cálcio (Ca), magnésio (Mg) e cobre (Cu) e do K nas formas solúvel e particulado, na enxurrada ocasionada por chuvas simuladas com diferentes intensidades aplicadas sobre solo manejado por cinco anos sob SPD, após aplicação superficial de adubo orgânico ou mineral. Os adubos não afetaram a concentração dos nutrientes estudados, exceto na condição da chuva mais intensa e solo sob adubação orgânica, onde a enxurrada apresentou maior concentração de K solúvel e K total. Independente do tipo de adubo utilizado, a chuva de maior intensidade ocasionou maior concentração de todos os nutrientes e formas estudados, evidenciando os benefícios econômicos e ambientais da adoção de práticas de contenção da enxurrada, mesmo em áreas cultivadas sob SPD.
The no-tillage system, has contributed to improvements in agricultural soils, among them the like increases in nutrient concentrations.of mineral elements in soil. However, it has been found that this increase concentration occurs mainly in the first few centimeters of the superficial top layer and so risks of nutrient losses by runoff, and associated of the soil, which concurs for losses of mineral elements through of runoff, with economic and environmental damages, are high. This study evaluated the total concentration, in runoff, of mineral elements potassium (K), calcium (Ca), magnesium (Mg) and copper (Cu) in total form and the soluble and particulate concentration form of K, in runoff caused to simulated rainfall of different intensitiesy applied over soil under no-till system and submitted to simulated after application of organic or mineral fertilizers in no-till soil. The fertilizers did not affect the concentration of mineral elements studied nutrients in runoff, except in condition of more high intense rainfall and soil under after organic manure application, which promoted runoff with showed the higher highest concentration of soluble and total K. Independent Irrespective of the type of fertilizers utilized type, the rainfall of higher intensity resulted in higher concentrations of all the mineral elements and forms studied, either in total, soluble or particulate form, evidencing the economic and environmental benefices, risks and suggesting that with the adoption of practices for runoff contention of runoff practices must be adopted , even in tilled croplands areas managed under no-till system.