Reduction in Ammonia Loss by Applying Urea in Combination with Phosphate Sources

A laboratory experiment was carried out to study the influence of 100 mg phosphorus pentoxide (P2O5) kg–1 soil from various phosphate sources on ammonia losses from soils amended with urea at 200 mg nitrogen (N) kg–1 soil. Irrespective of soil type, ammonia (NH3) loss was significantly greater from untreated soil (control) than from the soil treated with phosphorus (P) sources. A maximum decrease in ammonia loss (56%) was observed by applying phosphoric acid followed by triple and single superphosphate. Ammonia losses were significantly greater from sandy clay loam than from clay. Rate of ammonia volatilization was maximum during the first week of incubation and became undetectable for both soils at 21 days after incubation. The addition of phosphate sources significantly decreased pH in the sandy clay loam, but in the clay a significant decrease was observed only with the phosphoric acid addition. Addition of phosphate fertilizers was beneficial in reducing NH3 losses from urea.