Effects Of Reduction Application Of Controlled-release Nitrogen Fertilizer On Yield,Nitrogen Use Efficiency And Nitrogen Loss In Paddy Soil

Long-term plot experiment was carried out to study the effect of controlled-release fertilization reduction on yield, nitrogen uptake and four main nitrogen loss ways in paddy field. The results are as follows:?1? Controlled release urea has a big advantage over conventional urea in increasing rice yield, the yield of early rice of the same amount of controlled release urea treatment was significantly higher than conventional urea treatment, the yield of the late rice of the same amount of controlled release urea and controlled release urea nitrogen application reduction of 10% treatment was significantly higher than the same amount of controlled release urea treatment, difference of the early and late rice yield between conventional urea treatment with other treatments of the controlled release urea were not significant, indicating that the controlled release urea application reduction of 30% will not lead the yield to a significant reduction.?2? Compared with conventional urea treatment, controlled release urea can significantly increase rice nitrogen use efficiency and nitrogen agronomic efficiency, rice nitrogen use efficiency of the same amount of controlled release urea application reduction of 10%,20%,30% respectively increased 36.78,33.15,35.53 and 45.04 percent points,and late rice increased 36.95,60.19,48.07and39.79 percentage points; rice nitrogen agronomic efficiency of the same amount of controlled release urea reduction of 10%,20%,30% treatments respectively increased 1.41,1.75,2.12 and 2.54 kg/kg, late rice increased 1.42, 2.12,3.34 and 4.73 kg/kg.?3? Compared with conventional urea treatment, controlled release urea reduction treatment in particular the reduction of 30% can significantly reduce nitrogen loss in paddy field, TN runoff loss decreased 30.56%, NH₄⁺-N runoff loss decreased 23.41 percent, NO₃^--N runoff loss decreased 18.64%; TN leakage loss reduced by 28.53%, NH₄⁺-N leakage loss decreased 34.17%, paddy NO₃^--N leakage loss reduced 29.51%. During early growth nitrogen runoff loss was mainly in the form of NH₄⁺-N; while during late growth mainly in the form of NO₃^--N in paddy field. Nitrogen leakage loss is mainly in the form of NO₃^--N, accounting for 74%?92% of TN leakage loss amount in paddy field. Runoff and seepage loss amounts are the biggest in paddy field of the early maximum fertilization, therefore, to prevent the huge loss of nitrogen fertilizer in early is the key to reduce the amount of nutrient loss.?4? Release urea can significantly reduce the ammonia volatilization losses, with the reduction of controlled release nitrogen fertilize use, ammonia volatilization loss is also reduced. Compared with conventional urea treatment, the same amount of controlled release urea and reduction of 10%,20%,30% treatments,early rice ammonia volatilization loss respectively reduced 39.03%,43.19%,48.93% and 55.96%.;late rice decreased 31.48%, 50.61%,67.36% and 73.81%.?5? Compared with conventional urea, N₂O emissions from rice season the year of the equal amount of controlled release, controlled release urea reduction 10%,20%,30% treatments decreased 16.91%,44.60%,64.04%,76.86%, and difference of the N₂O emissions between nitrogen treatments reached significant levels. Compared with the same amount of controlled release urea, N₂O emissions by the year season rice of the controlled release urea reduction of 10%,20%,30% treatment decreased by 33.32%,56.72%,72.15%.?6?The nitrogen loss ways were mainly in the form of ammonia volatilization, leakage and runoff losses followed. Of all nitrogen application treatment, ammonia volatilization reached 32.76-97.30 kg/hm²; runoff loss reached 18.04-25.98 kg/hm²; leakage loss reached 39.07-54.81 kg/hm²; N₂O-N emissions stand in a relatively small amount, only 0.76-0.46 kg/hm².