Qualidade biológica do solo sob pastagem de Brachiaria brizantha em processo de recuperação com cinza vegetal

Abstract

Degradation is caused by processes that result in the reduction or loss of natural resources and ecosystem equilibrium. In order to promote the recovery of a degraded area, it is necessary to find the balance between the biotic and the abiotic means. In this way, the objective was to evaluate the microbial and enzymatic activity of the soil under a pasture area under recovery process with vegetal ash. The experiment was carried out at the Cotton Institute of Mato Grosso, in the municipality of Rondonópolis, MT. Soil samples were collected at a depth of 0-10 cm, in an area that received fertilization management with doses of vegetal ash and forms of application, following a randomized block design, factorial scheme 6x2, corresponding to six doses of vegetal ash (0; 3; 6; 9; 12 e 15 t ha-1) and two treatments of ash (incorporated and non-incorporated), with a striped arrangement, totaling 12 treatments and 4 replicates. As a reference, four soil samples were collected in native forest area. The samples were stored in plastic bags immediately after collection and kept at 4 °C until the beginning of the analysis. Soil microbiological and biochemical attributes such as carbon and nitrogen from microbial biomass, basal respiration, fungi and total bacteria, diazotrophic bacteria and enzymatic activity (Acid Phosphatase, β-glycosidase and Arylsulfatase) were evaluated. The results were submitted to statistical analysis using software R, with analysis of variance, regression test for gray doses and Scott-Knott's test for the application management at a significance level of 5% of error probability. From the analyzes performed, there was a significant interaction between the factors for basal respiration and acid phosphatase enzyme, with the best treatment being the 15 t ha-1 dose without incorporation. For the quantification of diazotrophic bacteria and the enzymes arylsulfatase and β-glycosidase there was an isolated effect only for the gray doses. The use of vegetal ash presents potential for the recovery of degraded pastures, since it maintains the enzymatic activity and the microbial growth of the soil in levels similar to those found in the native forest.