Efeito da época de dessecação da braquiária sobre a microbiota do solo e desenvolvimento e produção da soja

Abstract

The cultivation of soybean (Glycine max L. Merrill) has been increasingly promising and relevant to Brazilian agriculture. Technologies and studies aimed at the production of soy drive higher yields at each harvest. Conservation techniques stand out in this regard, including the use of mulch in the soil, which brings benefits such as protection against erosion, reduced runoff, increased infiltration and soil moisture, increased microbial activity and increased agricultural production. There are a number of forage species recommended for use in the off-season of the grains, in order to provide a favorable environment after desiccation for the next harvest. However, there is a window for carrying out this procedure that interferes in the system and in the management of the crop. In view of these gaps, the experiment was carried out in the experimental area of the Federal University of Mato Grosso do Sul, Campus of Chapadão do Sul with four times of desiccation of Urochloa ruziziensis, delineated in strips: 45 Days Before Sowing (DAS), 30 DAS, 15 DAS and 0 DAS, with subsequent planting of soybean to analyze the effects of material decomposition and interference with soil microbiota and crop productivity. The microbiological evaluation of the soil was carried out in three distinct periods: Pre-planting, Flowering and Post-harvest, by extracting the total DNA of the soil and later quantifying the abundance of the 16S rRNA gene from Bacteria. The evaluation of the decomposition of vegetable residues was carried out using litter bags at 30, 60, 90 and 120 days after desiccation. At the end of crop development, the production components and soybean yield were analyzed. From the results, it was concluded that 45 days before sowing soybean is the ideal time, among the alternatives evaluated, to carry out the desiccation management of brachiaria. During this period, greater abundance of bacteria in the soil and less decomposition of crop residues was revealed, and these variables were interrelated in order to provide the soybean crop with a more favorable environment for its development, allowing it to express its maximum productive potential.