Ammonia volatilization characteristics and related affecting factors of humic acid urea

Behaviors of humic acid compound urea in soil were studied under laboratory conditions. Results show that compare with common urea, the total ammonia volatilization from four humic acid compound urea fertilizers were decreased by 48.14%, 47.99%, 30.89%and 59.22%, among them the compound urea with water soluble humic acid content being 11.78%decreased most. The ammonia volatilization reduction of humic acid urea correlated significantly with its nutrient-release mode and soil ambient. The total ammonia volatilization correlated significantly with soil urease activity during initial period of incubation, the correlation coefficient between total ammonia volatilization and soil urease activity was 0.825 and 0.808 for the fertilizer incubated for 48 hours and 96 hours, respectively. The correlation coefficient between total ammonia volatilization and N leaching rate was 0.903. The correlation coefficient between total ammonia volatilization and content of NH+4-N was 0.869 at the initial stage of incubation.