Potassium fertilization and bioactivators on the soybean yield and soil microbiota

Soil microorganisms are of paramount importance for crop yield. This study aimed to evaluate the effect of potassium chloride doses associated with two bioactivation sources on soybean yield and soil microbial activity. The experimental design was randomized blocks, arranged in a 5 x 2 factorial scheme, with four replications, being the first factor potassium doses (0, 30, 60, 90 and 120 kg ha-1 of K2 O), using potassium chloride as a source, and the second factor soil bioactivation products: Penergetic (250 g ha-1) and Efficient Microorganisms (EM) (1:250), with 250 L ha-1 of spray volume. The KCl doses affected the soil microbial activity, while the soil bioactivating sources with the potassium chloride doses did not show significance for the leaf potassium content and soybean yield. K2 O doses higher than the maintenance dose for the soybean crop with EM negatively influenced the soil microbial biomass. The EM bioactivator associated with the maintenance dose of K for the soybean crop (60 kg ha-1) is the most appropriate treatment for soil microbial activity, as it is the condition that presents the most stable environment and the highest microbial efficiency.