Enhancing soil security in Brazilian Cerrado: composted sewage sludge as a sustainable conservation agriculture strategy

Oxisols in the Brazilian Cerrado are intensively cultivated due to their strategic importance in producing a range of commodities exported worldwide. To achieve high productivity, a large amount of conventional mineral fertilizer (CMF) must be used, which raises multiple concerns. Composted sewage sludge (CSS) is a promising organic fertilizer that enhances soil health while increasing agricultural sustainability. The objective of this study was to monitor soil chemical quality at two depths (0–0.1 m and 0.1–0.2 m) after CSS applications over three agricultural years under a no-tillage system. The experiment was conducted under field conditions by applying and evaluating five rates of CSS (0.0, 5.0, 7.5, 10.0, and 12.5 Mg ha –1 ) vs CMF with four replicates. CSS increased sum of bases (37.07 vs 31.22 mmol c kg⁻¹), base saturation (75% vs 58%), and P (33.50 vs 25.00 mg kg⁻¹), as well as Ca (28.75 vs 22.00) and Mg (37.07 vs 31.22 mmol c kg⁻¹) compared to CMF in the surface horizon. Over the three years, the available concentrations of P, Cu, Mn, and Zn increased in the soil with CSS application. The results indicate that CSS can be utilized as a complement to CMF, enhancing the chemical quality and soil security of tropical Oxisols. When applied at a rate of 10.0 Mg ha⁻¹, CSS can enhance soil chemical quality and the soil’s capacity to support crop production and environmental functions, while fostering a connection between urban waste management and agriculture, thereby ensuring sustainable land management in tropical agroecosystems.