Microbiological attributes in Oxisol cultivated with sugarcane in savanna region of Central Brazil

ABSTRACT The contribution of plant residues throughout the sugarcane cycles favors the increase of organic matter and the activity of microorganisms in the soil, especially in the surface layers. Soil texture also has an important effect on ecological processes and soil quality. In this context, the objective of this study was to evaluate soil biological attributes in different sugarcane cultivation cycles under mechanized harvesting in an Oxisol in the Savanna region of Central Brazil. The study was conducted in commercial areas under sugarcane cultivation during the 2018/2019 season, which were considered homogeneous in terms of soil and climatic conditions, with the source of variation among the areas being the cultivation cycles (C1: one cultivation cycle; C3: three cultivation cycles; C7: seven cultivation cycles) and a savanna vegetation area selected as a reference. Microbiological variables were determined in two layers, 0-0.1 and 0.1-0.2 m. The variables related to microbial biomass and texture were subjected to principal component analysis. Areas with longer sugarcane cultivation cycles show higher proportion of microbial biomass carbon in the total organic carbon in subsurface layers (microbial quotient). The performance of the soil microbial community, as expressed by total organic carbon and microbial biomass nitrogen indicators, was associated with higher presence of clay and silt, i.e., soil particles smaller than 0.02 mm. RESUMO O aporte de resíduos vegetais ao longo dos ciclos da cana-de-açúcar favorece o incremento de matéria orgânica e atividade de microrganismos no solo, especialmente nas camadas superficiais. A textura do solo também tem um efeito importante nos processos ecológicos e na qualidade do solo. Nesse sentido, o objetivo desta pesquisa foi avaliar atributos biológicos do solo em diferentes ciclos de cultivo de cana-de-açúcar sob colheita mecanizada, em um Latossolo da região de cerrado do Brasil Central. O estudo foi realizado em áreas comerciais de cultivo de cana-de-açúcar na safra 2018/2019, consideradas homogêneas em termos de condições edafoclimáticas, tendo como fonte de variação entre as áreas os ciclos de cultivo (C1: um ciclo de cultivo; C3: três ciclos de cultivo; C7: sete ciclos de cultivo) e uma área de vegetação de cerrado selecionada como referência. Foram determinadas variáveis microbiológicas nas camadas de 0-0,10 e 0,10-0,20 m. As variáveis relacionados à biomassa microbiana e textura foram submetidos à anál