Bioindicadores de qualidade do solo arenoso com o uso de solubilizadores de fosfato e fonte de fósforo na cultura da soja

Abstract

Brazilian soils, especially sandy soils, are characterized by low fertility and with phosphorus (P) little accessible to plants. One of the strategies for better use of this nutrient is the use of P-solubilizing microorganisms, which contribute to greater productivity and improves the biological quality of the soil. The objective of this work was to evaluate soil quality bioindicators in response to the use of different combinations of phosphate solubilizers in sandy soil cultivated with soybeans. The experiment was carried out in the municipality of Sonora - MS, in a commercial area with the first soybean harvest, in a soil classified as Quartzarene Neosol. The experimental design was in randomized blocks (DBC) with five treatments and five replications, totaling 25 plots which had 24 rows of 5 meters in length spaced 0.45m apart. The treatments were:1) Testemunha - no treatment in the sowing furrow; 2) Padrão Fazenda (PF): Azospirillum brasilense + Bradyrhizobium japonicum + Bacillus methylotrophicus + Trichoderma asperellum; 3) PF + Pseudomonas fluorescens (PF + Pseudomonas); 4) PF + bioestimulante organmineral (PF + orgânico) and 5) PF + fertilizante mineral (PF+ mineral). The variables evaluated were: carbon in microbial biomass (CBM), soil microbial respiration (RMS), metabolic quotient (qCO2) and enzymatic activity of the enzymes β-glucosidase and phosphatase. For the CBM variable, the PF + orgânico treatment presented the highest value (231,48 µg C g-1dry soil). In general, the PF and PF+orgânico treatments were those that provided the highest MBC values, as well as for the enzymes studied, and the lowest RMS and qCO2 values. Therefore, the use of different combinations of phosphate solubilizers improved the microbiological quality of the sandy soil.