Descompactação do solo e seus efeitos nos atributos químicos e físicos e produtividade de grãos

Abstract

Currently in many areas under no-tillage system (SPD), two harvests have been carried out per year, reaching in some situations up to three crops per year, for example, in systems with summer corn, followed by beans and, later, oats or wheat. With this, the traffic of machines in the areas has increased greatly, being able to appear soils with compacted layers. The objective of this study was to evaluate the practice of subsoiling, as well as the application of correctives in subsurface, aiming to improve soil chemical and physical conditions, and its effects on crop productivity in a production system with annual crops. For this, an area under SPD was selected ten years ago and a field experiment was installed with the following treatments: SPD - areas under no-tillage; SB2 = area under deep subsoiling every two years; SB3 - area under deep subsoiling every three years; SBC - deep and underwater subsoil area of 1440 kg ha-1 limestone (30% MgO, 60% CaO, 175% PRNT and 183% PN). In the average of all treatments, the highest Ca and Mg values were observed in the 0 to 20 cm layer compared to the other layers. When considering the depths 0 to 20, 20 to 40 and 40 to 60 cm, V% values were higher in the treatment with limestone (SBC), compared to SPD, after two years of the application of the corrective. When evaluating the resistance to penetration it is verified that no values higher than 2,0 MPa were found, in this sense, there was no physical restriction to the development of the cultures. The decomposition forms varying the time and limestone did not promote significant increases in productivity in relation to the SPD treatment.