Seasonal Variability of Soil Microbial Indicators in Sugarcane Production System

Objective: To evaluate soil microbial indicators in a dystrophic Red Argisol cultivated with sugarcane under mechanized harvesting in Northwestern Paraná, considering different positions along the hillslope and seasons of the year, with native vegetation as a reference. Theoretical Framework: Soil microbiota responds rapidly to environmental disturbances and is considered an early indicator of changes in soil quality. MBC, BSR, and qCO₂ allow inferences about carbon use efficiency and microbial resilience under agricultural management practices. Method: The study was conducted in Presidente Castelo Branco – PR, in a dystrophic Red Argisol cultivated with sugarcane, with four treatments (three under cultivation and one with native vegetation) in 2-ha plots. Soil samples (0–10 cm) were collected in the summer of 2022 and autumn of 2023 for analysis of microbial biomass carbon (MBC), basal respiration (BSR), and metabolic quotient (qCO₂). Results and Discussion: In 2022, native vegetation showed higher MBC, while in 2023 there was an increase in cultivated areas. BSR and qCO₂ revealed microbial stress in the upper third of the hillslope, followed by recovery associated with straw deposition and favorable environmental conditions. Research Implications: Microbiological indicators proved efficient in detecting management-related changes, reinforcing their importance for monitoring soil quality in sugarcane systems. Originality/Value: This study contributes to understanding microbial dynamics in Argisols cultivated with sugarcane under mechanized harvesting, highlighting the relevance of sustainable management practices for the resilience and efficiency of soil–plant systems.