Cover crop and deep tillage on sandstone soil structure and microbial biomass

Abstract

ABSTRACTThe aim of this study was to evaluate and quantify structural volumes of dystrophic Red-Yellow Latosol, submitted to localized deep soil tillage in sugarcane crop after cultivation of millet and crotalaria, and verify the effect of these managements on microbial biomass. Three management systems were evaluated: localized deep soil tillage (without cover crop), localized deep soil tillage and millet cover crop, and localized deep soil tillage and crotalaria cover crop. For each management three trenches were dug for crop profile description and carbon and nitrogen of microbial biomass were evaluated. Non-utilized profiles of covering plant submitted to localized deep soil tillage presented soil volumes with more morphologically compact structure and smaller porosity than millet and crotalaria profiles. These structures occupied 53.3% of total area of localized deep soil tillage profiles, which presented roots with a more flattened and tortuous aspect. A higher content of microbial biomass carbon (285 mg kg−1 soil) was found in the volume of cracked soil inlocalized deep soil tillage and millet management while lower contents of microbial biomass carbon (23 mg kg−1 soil) and microbial biomass nitrogen (4 mg kg−1 soil) were obtained in localized deep soil tillage compact and laminar structure. Despite covering plant utilization before localized deep soil tillage, the effect of this practice had consequences to the functionality of sandstone soil.