Mobilidade de íons em solo sob sistema de semeadura direta submetido às adubações mineral e orgânica

Abstract

The retention in soil profiles of surface-applied mineral elements is crucial to maintain the water quality and reduce environmental and economic damages. This study evaluated: the mobility of potassium, calcium and magnesium, aluminum and organic matter contents and changes in pH in an Eutroferric Red Latosol under no-tillage, and the chemical oxygen demand (COD) of percolated water. Mobility was assessed in an undisturbed soil column with preserved structure and treated with mineral (100 kg ha-1) and organic (150 m3 ha-1) fertilization. Mineral fertilization increased K, Ca2+ and Mg2+ leaching, although the quantity of K applied was greater in the organic than in the mineral fertilizer. The COD of percolated water under organic fertilizer was significantly reduced. Soil Ca and Mg contents were highest in the 0- 2.5 cm layer, mainly under organic fertilization. Organic fertilizer did not raise the soil organic matter content, but reduced soil pH by one unit and neutralized Al3+ Results of this study show how soil plays the role of a filter of contaminated water, evidencing the economic and environmental benefits in the case of runoff infiltration from croplands.