Impacto de sistemas de culturas em atributos do solo e produção de soja em plantio direto

Abstract

The search for understanding the effect of agricultural systems on the quality of the agro ecosystem is fundamental for the definition of efficient production systems from a social, economic and environmental point of view. Crop rotation is characterized as a strategy to improve the physical, chemical and biological attributes of the soil, making agricultural systems more sustainable. The objective of this work was to evaluate the dry biomass and the chemical composition of the straw of crops in the second harvest, the chemical, physical and microbiological attributes of the soil and the productive components of soybean in crop rotation and succession systems in a long-term experiment. The experiment was implemented at the Agrarian Sciences Experimental Farm of the Federal University of Grande Dourados (UFGD), in the municipality of Dourados, MS. The experimental design used was randomized block, with six treatments composed of two successions (soybean / corn and soybean / corn + brachiaria) and four crop rotations (millet, white oat, niger and sunnhemp) in winter, associated with soybean and the corn alternated in the summer. We evaluated the dry mass of the plants in the autumn / winter and the nutrient content in full flowering, the straw on the soil in the pre-sowing of soybean, the chemical (nutrient content) and physical soil characteristics (macroporosity, microporosity, density and penetration resistance) in the 0-10 and 10-20 cm layers. Biomass and microbial activity were also evaluated in the 0-10 cm layer. The consortium between corn + brachiaria and millet are great options for dry mass production, the sunnhemp absorbs the highest nutrient contents. The succession treatments promoted lower potassium content in the 0-10 cm layer and the single cultivated corn lower phosphorus content in the 10-20 cm layer. The cultivation of single corn led to lower soil macroporosity and corn intercroppered with brachiaria higher penetration resistance values. Higher microbial biomass and efficiency in the use of carbon were observed in treatments containing crop rotation in relation to succession, especially containing sunnhemp. The treatments involved in crop rotation provided higher soybean productivity, with the sequence involving white oat standing out.