Leaching and transforming characteristics of different nitrogen fertilizers added by fertigation

Soil column was used to study the characteristics of the movement, transformation, and leaching of different kinds of nitrogen fertilizers in soil added by fertigation. The result shows that the amount of nitrogen leaching was in the decrease order of NO3--N fertilizer>urea>NH4+-N fertilizer, and the main form of N leaching was the N-fertilizers added. The amount of nitrogen leaching in sandy loam soil exceeded in clay loam soil. Applying NH4+-N fertilizer significantly increased the content of NH4+-N in soils, and as the processing of nitrification the content of NH4+-N was reduced, and NO3--N was increased gradually. After applying the urea, the content of NH4+-N in soils reached up to the peak at the fifth day, and then began to decrease because of the occurring of the nitrification. The content of mineral nitrogen content (NH4+-N + NO3--N) decreased during the incubation period after applying NH4+-N fertilizer and urea. It might be related to the occurrence of NH4+-N fixation and volatilization.