Implicações da adição de fontes de fósforo sob indicadores microbianos e bioquímicos do solo

Abstract

Phosphorus is a vital nutrient for terrestrial organism due to its importance in cellular metabolism. Highly weathered soils have low availability of P in the soil solution due to the adsorption of phosphate in the soil matrix, such as iron and aluminum oxides. The soil microbiota is preponderant in the availability of P in the soil solution due to the dynamics of immobilization and mineralization and rapid cycling. The objective of this work was to evaluate the impact of the addition of different P sources on soil microbial and biochemical indicators (Soil microbial respiration (SMR); Microbial Biomass Carbon (MBC); Soil Metabolic Quotient (qCO₂); FDA; acid phosphatase activity). The work was carried out on a sample of a Oxisoil, collected in Uberlândia, MG. The experiment was installed in a glass flask (600 mL) with 100 g of soil and 300 mg of P kg⁻¹ of soil was added. The treated with four replications were assembled to evaluate the source of P: 1- control, 2- potassium monophosphate (KHPO₄), 3- simple superphosphate, 4- phosphate rock dust, 5- phytic acid, 6- inositol. The results show that phytic acid had a significant increase compared to the other sources, with a lower SMR value being observed in the treatment with KHPO₄ of the phosphate sources. The addition of P, regardless of the source, tends to decrease MBC in the soil compared to the control treatment, leading to an increase in qCO₂ in the treatments with P addition. The addition of P sources significantly affects the FDA activity, with the highest values found in the treatment with the addition of KHPO₄. A lower FDA activity was not found in the phytic acid treatment. Treatments with P did not affect the phosphatase activity in the soil when compared to the control treatment. Concluded that the addition of phosphorus sources differentially alters soil metabolism, but this alteration may be specific to a soil bioindicator.