Agronomic performance of maize and cover crops using composted sewage sludge to supply phosphorus

The application of composted sewage sludge (CSS) in crop production offers a sustainable solution for nutrient recycling and reducing reliance on mineral fertilizers. This study evaluated the residual effects of CSS on phosphorus (P) bioavailability and agronomic performance of maize and cover crops in P-fixing soils of the Brazilian Savannah (Cerrado). A field experiment was conducted over three cropping cycles (third, fourth, and fifth season), applying CSS at rates of 0, 5, 7.5, 10, and 12.5 Mg ha- 1 (wet basis) alongside conventional mineral fertilizer. The results showed that CSS significantly enhanced P uptake and maize (Zea mays L.) yield, with linear increases in plant height and grain yield (up to 28%) in the third season. Marandu grass (Urochloa brizantha (A. Rich.) T.Q. Nguyen cv. Marandu) growth responded positively to CSS, while a cover crop mix showed no response. Soil available P increased linearly with CSS rates, though climatic variability influenced outcomes. This work shows CSS demonstrates potential as a sustainable P source, but its efficacy depends on management practices and environmental conditions.