Variabilidade horizontal da deposição de resíduos pós-colheita de soja e sua influência na ciclagem de fósforo e potássio

Abstract

Brazil is a world leader in the production and export of soybeans. In addition, the country holds this role with high environmental sustainability in production, through practices such as the No Till System, where the distribution of plant residues plays a major role in the uniform cycling of nutrients such as phosphorus and potassium into the soil. This study aimed to evaluate and quantify the horizontal variability of post-harvest soybean deposition, verifying the influence of this phenomenon on the cycling and availability of phosphorus and potassium nutrients in the soil, investigating the effects of this variability on the biomass production of the successor crop of forage turnip. For this purpose, an experiment was implemented during the 2019/2020 agricultural year in a commercial soybean crop located in the municipality of Cândido Godói - RS, where after the harvest 4 sequential collection points were arranged across the direction of the harvester displacement, called treatments T1: allocated in the strip corresponding to the center of the harvester passage, T2: arranged in the strip adjacent to the left side of the harvester passage, T3: designated in the strip between crossings of the harvester platform, and T4: allocated in the strip corresponding to the right side of the passage of the harvester, which were subjected to 10 replications, totaling 40 points of collection of post-harvest soybean residues and 40 collections of fresh forage turnip mass, both of which were vegetable materials subjected to dry matter mass quantification. The data referring to nutrients were obtained from the consulted literature. The dry matter values were subjected to analysis of variance and the averages compared to each other by the Tukey test at the level of 5% probability. The deposition of post-harvest soybean residues showed horizontal variability, with a greater amount of dry matter in the central passage of the harvester. This poor distribution of waste caused unevenness in the supply of phosphorus and potassium to the soil in the different deposition ranges, and the production of turnip biomass implanted in the sequence presented a positive correlation with the residue, however it was not significantly influenced by the variability of deposition of waste.