Atributos físicos do solo e características agronômicas da soja em sistemas de sucessão e rotação de culturas

Abstract

Among the challenges of current agriculture, it has become increasingly necessary to identify management systems that preserve and improve the physical attributes of the soil, combined with high productivity. This study aimed to evaluate crop succession and rotation systems regarding the production of straw and biomass of species cultivated in autumn/winter, the physical attributes of the soil and the agronomic characteristics of soybean. The experiment consisted of eight treatments, using three succession systems (soybean/fallow, soybean/corn and soybean/corn+brachiaria) and five crop rotation systems in the winter period (millet, millet + Crotalaria ochroleuca, white oat , vetch and forage radish). The experimental design was randomized blocks with four replications. In 2018 and 2019, the production of dry biomass and the respective residue (straw) left in the soil in each system and the agronomic characteristics of soybeans in the 2018/19 and 2019/20 harvests were evaluated. The macroporosity; microporosity; total porosity; Soil density and soil penetration resistance were evaluated in layers 0-10, 10-20, 20-30, 30-40 and 40-50 cm in soybean pre-sowing in the 2018/19 crop. The evaluations regarding soil aggregation, geometric mean diameter and organic matter were carried out only in the 0- 10 and 10-20 cm layers in the 2018/19 harvest. Among the systems studied, the intercropping between corn and Brachiaria was highlighted in the 2018/19 and 2019/20 harvests, producing the highest amounts of dry biomass of the aerial part. The highest amounts of straw in soybean pre-sowing were found in the rotation systems with the cultivation of millet + C. ochrouleuca in the 2018/19 harvest, and in the soybean/corn+brachiaria succession and rotations with vetch and forage radish in the harvest 2019/20. The highest levels of macroporosity, total porosity and lowest values of soil density and soil penetration resistance were found in the soybean/corn+brachiaria succession systems and in the treatments that involved crop rotations. With the exception of soybean in monoculture, all crop rotation or succession systems influenced the increase in soil organic matter contents and, consequently, a better state of soil aggregation. The highest soybean yields were obtained in treatments that involved crop rotations.