Effects of Water Retaining Agent on Ammonia Volatilization and Nutrient Leaching Loss from N, P and K Fertilizers

Static adsorption and soil column leaching methods were used to study the effect of water retaining agent (WRA) in soils on ammonia volatilization from urea and nutrients leaching loss from urea, monoamonium phosphate and potassium chloride. The results showed that WRA strongly restrained ammonia volatilization. The amount of ammonia volatilization obviously decreased with the increase of WRA application level. The decrease of the amount of ammonia volatilization was closely related to soil water content, soil urease activity and pH value. When the soil water content was higher, the soil urease activity and pH value were lower, the amount of ammonia volatilization was fewer. When the soil water content were 75% and 100% of field water capacity with 0.05%~0.80% WRA applied, the total accumulated amount of ammonia volatilization decreased by 8.97%~47.65% and 16.78%~72.40% compared with that of the controls, respectively. Applying WRA into soils also could reduce leaching loss of N, P and K nutrients. For N and K nutrients, the leaching loss amount significantly decreased with the increase of WRA application level, but for P nutrient, it did not. When the application level ranged from 0.05% to 0.2%, the total accumulated amount of leaching loss of N, P and K decreased by 13.60%~39.62%, 28.31%~16.96% and 6.76%~24.55% compared with that of the controls, respectively.