Atividade biológica em um latossolo sob pastagem de Brachiaria brizantha adubada com cinza vegetal

Abstract

In the state of Mato Grosso, agriculture is the main economic activity, as it contributes strongly to the development of the region. The agricultural sector continues to expand and the use of new technologies to promote a balance between production and soil quality becomes increasingly necessary. Thus, the objective was to evaluate the biological and enzymatic activity in a soil under a pasture area in the process of implantation and fertilized with wood ash. The experiment was installed in the experimental field of the Federal University of Rondonópolis, Rondonópolis-MT, under pasture that was established in 2018, with a randomized block design, 5x2 factorial scheme, consisting of 5 doses of wood ash (0, 8, 16, 24 and 32 t ha-1 ), two forms of application of wood ash (incorporated and non-incorporated), arranged in strips, totaling 10 treatments, with four replications. Soil samples, classified as Dystrophic Red Latosol, were collected at a depth of 0-0,10 m and in two periods (dry and rainy), in the first year of pasture implantation. Four soil samples referring to the native forest were collected to use as a reference, as it is a preserved environment. The evaluation of microbial activity and soil quality were measured using biological attributes such as: carbon and nitrogen from microbial biomass, basal respiration, metabolic quotient, diazotrophic bacteria and the enzyme acid phosphatase. Data were subjected to statistical analysis using the R computer program, with F test for analysis of variance, regression test for gray doses and Tukey test for application management at 1%, 5% and 10% significance levels. The results showed a significant interaction for the metabolic quotient in both periods, showing better results with the doses of ash corresponding to 0 and 8 t ha-1 with non-incorporated management, and diazotrophic bacteria, specifically the NFb and JNFb mediums for the dry period, with the dose of 8 t ha-1 of ash incorporated into the soil. The acid phosphatase showed better results for non-incorporated management, with doses below 24 t ha-1 of ash. Biomass carbon and diazotrophic bacteria present in the the JMV culture medium showed an isolated effect for the doses of wood ash, while biomass nitrogen and basal respiration showed an isolated effect for the applied management. The use of wood ash showed a positive effect on soil quality, increasing soil microbial biomass and acid phosphatase enzyme activity.