Melhoria dos atributos químicos do solo pelo uso de corretivos, condicionador e fertilizantes aplicados em superfície e incorporado com escarificador e a produtividade da soja

Abstract

Brazil is the second largest producer of soybeans worldwide, however, the improvement of soil chemistry through liming could raise productivity even more, especially in years of water deficit. In this context, the work had as objective to evaluate the response of the soybean crop under different sources of calcium and magnesium applied on surface and incorporated and its effect on the chemical characteristics of the soil. The experimental design was through randomized blocks with three replications, in commercial area in the city of Julio de Castilhos-RS. The treatments were as follows: control (T0); correction with dolomitic limestone for ½ SMP according with the recommendation of the CQFS RS/SC (2004) (T1); T1 incorporated (T2); 1 SMP (T3); T3 incorporared (T4); correction to balance the bases: Ca 60% Mg 15% e K 3% (T5); T5 incorporated (T6); T5 with addition of 2 Mg ha-1 of agricultural gypsum and T8 with 200kg of calcite. Soil samples were stratified at depths of 0,0-0,10 m, 0,10-0,20 m and 0,20-0,40 m at two sampling times (9 and 21 months). The yields of the soybean crop (two harvests) were evaluated. There was improvement in pH H2O in the surface layer in all treatments, and in the subsurface layer in the second collection, but the treatment 5 in the first collection presented the lowest level of Al+3, and higher relative productivity accumulated. The planned Ca/Mg ratio was not achieved, but there was a chemical improvement in the soil profile with increase in Ca+2 and Mg+2 compared to the control. As for the application method, superficially was economically viable, moreover, the improvement in nutrient contents proved to be more important than the relation between nutrients.