Degree of dispersion, microbial biomass and organic carbon of an oxisol cultivated with soybean under conventional and no-tillage in the cerrado (savannah) of the west of Bahia, Brazil

Abstract

Anthropogenic action on soil commonly results in degradation of this natural resource, largely due to inadequate agricultural practices. Therefore, it is imperative to adopt alternatives to mitigate soil degradation, given its close relationship with the management used. In this context, the objective of this study was to evaluate the quality of a sandy loam Oxisol cultivated with soybean under conventional (CT) and No-tillage system (NT_S) in the Cerrado (Savannha) of the western region of Bahia, Brazil. For the evaluation, water dispersed clay (WDA), flocculation degree (FD), degree of dispersion (DD), total organic carbon (TOC), microbial biomass carbon (MBC) and the microbial quotient (q Mic) were used as indicators of soil quality. The study was developed in an experiment conducted in the Experimental Station of the Fundação de Apoio à Pesquisa e Desenvolvimento do Oeste Baiano, municipality of Luís Eduardo Magalhães, Bahia, Brazil. The treatments consisted of soybean plots cultivated under conventional and No-tillage system. As a reference, soil samples were collected in an area of ​​Cerrado native (CN) with phytophysiognomy of dirty field, adjacent to the experimental area. The CT_S treatment promoted increase in WDC and soil DD values, while FD, TOC, MBC and qMic values ​​were reduced. In contrast, in NT_S, WDC and soil DD levels were reduced, while FD, TOC, BMC and qMic were promoted, evidencing the ability and importance of NT_S to favor soil quality. Soil FD is positively related to TOC, which is reduced under conventional tillage, evidencing the importance of no-tillage as a system capable of promoting flocculation, biology and soil quality.