Potencial de aplicação no solo e aproveitamento agrícola de biossólidos de esgoto sanitário

Abstract

The use of biosolids, residues derived from wastewater treatment plants and agro-industrial processes, has emerged as a sustainable strategy for improving soil fertility, increasing agricultural productivity, and promoting the circular economy. This study aimed to evaluate the effects of applying Class II biosolids, obtained from the Wastewater Treatment Plant (WWTP) of Nova Serrana–MG, on the chemical and physical properties of a Red-Yellow Latosol, as well as on the initial development of maize crops, considering different application rates and incubation periods of the residue in the soil. The research was conducted through a Systematic Literature Review and field experiments, involving the application of biosolid doses to the soil and a bioassay using the proposed doses combined with soil correction. Parameters such as organic matter, organic carbon, cation exchange capacity (CEC), initial growth, accumulated biomass, and nutrient allocation in plants were evaluated. The results demonstrated that the application of biosolids improves soil quality, including increases in organic matter, stable carbon, water retention capacity, and overall fertility. Additionally, it contributes to climate change mitigation and the recovery of degraded areas. The need for monitoring contaminants, such as heavy metals, and for long-term evaluation to ensure environmental safety and economic sustainability was also emphasized. Experimental results indicated positive responses of organic matter and organic carbon to the applied agronomic doses, with a statistically significant maximum effect observed between 100 and 150 t ha⁻¹. The CEC showed a significant increase, particularly for Ca²⁺, Mg²⁺, and K⁺, demonstrating accumulation from initial correction through stabilization. The application range between 80 and 120 t ha⁻¹ was identified as the optimal agronomic dose to maximize the variable from a statistical perspective. The application of biosolids positively influenced root growth, accumulated biomass, and the root-to-shoot ratio. Intermediate doses (20–40 t ha⁻¹), combined with soil correction, yielded the best statistically significant results, whereas higher doses above 120 t ha⁻¹ without correction led to phytotoxic agronomic effects. An increase in organic carbon was observed, serving as an environmental and agronomic indicator of proper biosolid management. In summary, the study confirms that biosolids can be safely and efficiently applied in agricultural systems, promoting agronomic gains, environmental benefits, and contributions to sustainability, provided that recommended doses are followed, contaminants are monitored, and local soil and climate conditions are taken into account.