Efeito da profundidade sobre a atividade de enzimas de solo com culturas agrícolas em Goiás

Abstract

The state of Goiás is the Brazilian federation unit that most represents the Cerrado biome in its area, although its remnants have dwindled dramatically with the intensification of agriculture and livestock. Even considering the economic advantages of agricultural activities, it is known that they cause changes in the chemical, physical and biological properties, affect the dynamics of soil functioning, which depends on the organic matter transformation mechanisms mediated by microorganisms and extracellular enzymes. The objective of this study was to understand the dynamics of soil functioning by analyzing the influence of depth, using the monitoring of enzymatic activity in annual and perennial cultivation areas in comparison to native Cerrado areas. The samples were collected at depths of 0-10 cm, 10-20 cm, 20-50 cm and 50-100 cm in 12 municipalities in the state of Goiás. The soils collected were analyzed chemically for the determination of the organic matter content, carbon and total organic nitrogen, as well as nutrients and cation exchange capacity. The activities of the glycine aminopeptidase, alpha and beta glycosidase, acid phosphatase, protease and urease enzymes were also measured. The data were analyzed by analysis of variance (ANOVA Three-way and Two-way), multivariate analysis (MANOVA) and analysis of main components (PCA) and the means were compared and tested a posteriori (Tukey test, p <0.05). The chemical properties were less efficient in the detection of changes from soil management systems. The α-glycosidase enzyme showed no activity for any of the soils sampled. The enzymes glycine aminopeptidase, β-glycosidase and acid phosphatase presented lower activities for the agricultural areas in relation to native Cerrado soil, and when evaluated individually, the highest activity occurs up to 20 cm depth. Protease and urease enzymes showed significantly similar activity values between cultures in relation to the native Cerrado. However, when the enzymes were evaluated together, with increasing soil depth there was a decrease in their activity. Thus, the evaluation of several enzymes related to the mineralization of different soil components can be an efficient tool in monitoring their quality.