The Study On Fate Of Fertilizer Nitrogen By Different Ways Of Fertigation

[Object] In this research, the fertilizer N movement in drip irrigation and flooding irrigation was studied, the account and the proportion that the residue of fertilizer N in soil, ammonia volatilization, N uptake and denitrification were measured. The fate of fertilizer N and the N movement in different irrigation system and applied-N level were illustrated.This can provide the theory basis for optimizing fertilizer in drip irrigation in arid area.[Methods] This study adopted soil column for simulating field condition. By using of 15N tracer technique, the residue of fertilizer N in soil and nitrogen content in cotton plants were measured. A set of self-designed equipment were adopted to simulate wind tunnel for pumping ammonia from the column to a collector and then to determine the amount of ammonia volatilization, the amount of denitrification was accounted by N-balance equilibrium.[Results] The main results were as follows:1. The dry matter of cotton was increased with the increase of applied-N amount in different irrigation system. Two-way Analysis of Variance(ANOVA) showed that fertilization and irrigation on cotton dry matter weight was a significantly difference.2. The nitrogen content in cotton plant was increased with the increase of applied-N amount in different irrigation method. In the high applied-N level a significantly higher the cotton 15N fertilizer was found in drip irrigation than in flooding irrigation, but in low applied-N amount was no significantly difference.3. The NUE of cotton was decreased with the increase of applied-N amount in different applied-N levels, the NUE of DN240, DN360, DN480 treatments was respectively 71.61%, 56.16%,48.93%, and the NUE of FN240, FN360, FN480 treatments was respectively 62.63%, 45.80%,43.64%. The NUE of cotton in drip irrigation was higher than flooding irrigation.4. The residue of 15N fertilizer showed low-high-low pattern in 0-100 cm soil profile. In drip irrigation treatments, the residue of 15N fertilizer was the highest in the 0-40 cm, while the residue of 15N fertilizer was deeper distributied in the 60-80 cm in flooding irrigation. And the rate of N residual in DN240, DN360, DN480, FN240, FN360, FN480 treatments is 18.32%, 28.20%,29.52%,35.55%,31.33%,39.58%.5. N loss through ammonia volatilization was a significantly difference in different irrigation systems and it was increased with the increase of applied-N amount as well. During the whole growth period, it was showed decreasing tendency for the amount of ammonia volatilization. The ammonia volatilization loss of fertilizer-N were vibrated between 0.28%to 11.47%.6. Denitrification loss was from 7.89% to 14.86%, and the drip irrigation treaments was lower than the flooding irrigation.7. In the same applied-N level, the NUE of cotton in drip irrigation treatment was higher than flooding irrigation treatment and the residue of 15N fertilizer was lower than flooding irrigation treatment, and the ammonia volatilization was higher than flooding irrigation treatment, while denitrification loss was lower than flooding irrigation treatment. leaching has a higher risk in flooding irrigation than in drip irrigation.