| A series of experiments on the effect of rice yield,quality and ammonia volatilization losing,the fate of nitrogen fertilizer on different N-application rates,different nitrogen regimes and with different use methods in Changshu, Jiangsu province. The main purpose was to find out the feasible amount and manage method of nitrogen fertilizer in paddy field for the area. The main results were as follows:1. The yield and yield formation of rice were regulated significantly by N-application rates,different nitrogen regimes,different use methods . it had defined that the high yield mode of nitrogen using in Tai Hu region was that the appropriate amount of nitrogen fertilizer of Suxiangjing 1 was 200kg/ha～250kg/ha, and could get the rice yield of 9000kg/ha and or so; the appropriate amount of nitrogen fertilizer of Wuyunjing 7 was 225kg/ha～262.5kg/ha, and could get the rice yield of 9000kg/ha and or so; The improved method of apply fertilizer,which broadcast N onto and then incorporation with drained soil before transplanting and broadcast N carried by water into soil for top dressing could increase the rice yield.2. Rice quality showed that the brown rice ratio,milled rice ratio and head rice ratio were also increased with the N-application rate. At the same N-application level, while the ratio of nitrogen applied at the earlier stage was larger, the brown rice ratio descended, but the milled rice ratio and head rice ratio increased, and the milling quality was better. According to the result, the milling quality and most indexes of the appearance quality were better with the N-application rate increased, but some indexes of the appearance quality and cooking quality were worse. The effects of N-application rate on pasting traits showed that with N-application rate, the breakdown increased at first and then descended, but the setback descended at first and then increased, and when the N-application rate was between 200kg/ha～250kg/ha, the rice quality was better. The effects of different nitrogen application on rice quality were that the brown rice ratio,milled rice ratio,head rice ratio and chalk ratio,chalkiness were all descended with the N-application rate increased, the rice quality was better at the treatment 6:4~5:5. The quality had no obviously varied trend with the nitrogen use method.3. The effects of N-application rate on nitrogen use efficiency of rice showed that the total N the rice absorbed increased with the N-application rate, but the nitrogen use efficiency descended. More N-application also reduced the nitrogen agronomy efficiency,physiological efficiency and dry matter accumulation production efficiency,rice production efficiency. Optimized method of apply fertilizer, especially at high N-level, could improve the yield of rice and nitrogen use efficiency. From the result of 15N micro-area experiment, the rate of nitrogen fertilizer absorbed in paddy field was 21.68%-31.92%. And it became lower if more nitrogen fertilizer was used, there was 56.10%-72.03% nitrogen fertilizer losing in paddy field. The remained N in soil distributed mainly in 0-40cm deep, and almost 70% N remain in 0-20cm deep soil.4. The relationship between ammonia volatilization losing and the apply amount of nitrogen fertilizer was linearity relation. And in rice field, the ammonia volatilization losing lasted shorter time, which took place almost in a week after fertilizing, the ammonia volatilization losing was 7.34±1.28% with optimization method and 9.65±1.48% with conventional method,almost 40% of total ammonia volatilization losing took place during the base fertilizer stage, in the district with ratio of nitrogen applied was 4:6, while the N-application was higher during the panicle fertilizer stage which wasunder higher temperature, the ammonia volatilization losing was more and more, this showed that we should reduce the N-application during that stage. The improved method of apply fertilizer could obviously reduce the ammonia volatilization loss.No matter the optimized method or conventional method, the results of three years all showed that the concentration of NH4+-N reach its max value in three days after fertilized, and then decreased with the time go; the concentration of N03--N and NH4+-N took a mutual ebb and flow dynamic in one week after fertilized, and the concentration NH4+ had a obviously positive relation with ammonia flux. The concentration of each kind of nitrogen in field surface water is relative higher in one week after fertilized, and it increase with the increasing of nitrogen fertilizer, the each kind of nitrogen in field surface water with the improved method is lower than that with conventional method, so the key period of surface water manage in paddy field is a week just after fertilized.Take the environment effect, agrinomy effect after nitrogen fertilizing into account, in Taihu basin, the appropriate amount of nitrogen should be limited about 200kg/ha～250kg/ha, nitrogen applied at the earlier and middle-later stages in a ratio of 5:5~6:4 would be suitable, and the improved method of apply fertilizer could increase the rice yield, quality, nitrogen use efficiency and reduce the nitrogen loss in this area.
|
PDF Full Text Request