Ammonia emission from sandy loam soil amended with manure compost and urea

Urea is a renowned nitrogen (N) fertilizer widely used in plant N nutrition owing to its high N concentration (46%). The effect of the N application rate on ammonia (NH3) emission into the environment and soil properties is yet to be unraveled. The rate of NH3 emission from sandy loam soil amended with manure compost (T1: 5000 kg ha(-1)) and urea at different application rates (100, 200, and 400 kg N ha(-1) designated as T2, T3, and T4, respectively) with 3 replications was evaluated in an incubation experiment. Ammonia emission was rapid at the early stage of the experiment followed by an equilibrium decrease that tends toward zero at the end of the incubation. Ammonia emissions of 16.50, 52.15, and 75% of applied N in T2, T3, and T4 were observed on day 49. Ammonia emission increased linearly (y = 0.7823x-32.169, R-2 = 0.95**) in response to N application rates. T1 conserves more NH4+ (20.79 mg kg(-1)) in the soil, followed by T2 (11.8 mg kg(-1)) and T3 (11.7 mg kg(-1)). T2 and T3 reduced the soil pH to optimal for microbial activities and nutrient availability, while T4 promoted soil acidity. A balanced combination of compost and urea mitigates NH3 volatilization and improves soil fertility. In conclusion, applying compost (5000 kg ha(-1)) with urea at 100 kg N ha(-1) or 200 kg N ha(-1) is recommended for NH3 volatilization mitigation, nitrification inhibition, and efficient NH4+ retention in the soil.

Automated summary

The effect of different nitrogen application rates on ammonia emissions and soil properties was evaluated. The study recommends applying 100 kg or 200 kg of urea on a compost base for reducing ammonia volatilization, inhibiting nitrification, and improving NH4+ retention in the soil.