Plantas de cobertura melhoram a disponibilização do fósforo e micorrização da soja?

Abstract

Cover crop cultivation improves soil fertility and benefits subsequent crops, in addition to promoting nutrient cycling, especially phosphorus. In this sense, the objective of this study was to evaluate the changes promoted by cover crops in soil chemical attributes, glomalin production, mycorrhization rate, soil phosphorus sorption, and nutritional attributes and agronomic characteristics of soybean. For this purpose, the study was developed in the experimental area of the School Farm of the Federal Institute of Mato Grosso do Sul, Naviraí Campus. The experimental design was randomized blocks, with six treatments and four replicates, totaling 24 experimental units. The treatments consisted of: Treatment 1- Soybean/Fallow; Treatment 2-Soybean/Millet; Treatment 3- Soybean/Crotalaria (Crotalaria ochroleuca); Treatment 4-Soybean/Forage radish; Treatment 5- Soybean/Second-crop Corn and Treatment 6- Soybean/Second-crop Corn + Brachiaria (Urochloa ruziziensis). Soil samples were collected before soybean cultivation, at flowering and after crop harvest. The soil chemical attributes (pH, OM, P, K, Ca, Mg, H+Al, SB, CTC, V% and P sorption), glomalin content, soybean root mycorrhization rate, nutritional attributes and agronomic characteristics of soybean (plant height, population, number of pods, number of grains, weight of 1000 grains and productivity) were evaluated. The data were submitted to analysis of variance (ANOVA) and when significant to the F test and the comparison of means was performed by the Scott-Knott test at 5% probability. In the chemical attributes, crotalaria presented the best results for most of the variables analyzed. Glomalin production was not affected by the treatments, but was influenced by the collection times, with the highest concentrations occurring during flowering and after soybean cultivation. Regarding the mycorrhization rate, crotalaria and fallow presented the highest percentages of mycorrhizal colonization. Cover crops were efficient in reducing phosphorus fixation in the soil (P sorption). Agronomic characteristics were positively affected by cover crops. Therefore, productivity was enhanced by the presence of cover crops, together with the chemical attributes and other parameters evaluated.