Effects of Nitrogen and Phosphorus with Different Levels on Grains Yield and Absorption and Utilization of Fertilizers' Nutrient in Nansihu Basin

For determining reasonable paddy fertilizer inputs including nitrogen and phosphate in Nansihu basin while reducing the loss risk of nitrogen and phosphorus,it was studied that paddy yield,absorption and utilization of fertilizer in paddy with different levels of nitrogen and phosphorus.The results showed that treatment without N,P fertilizer application declined N and P content while reducing grains production significantly.Treatment with reducing N and P fertilizer application by 30% enhanced utilization efficiency of N and P fertilizer prominently.Meanwhile,it also decreased grains production obviously.Excessive N and P fertilizer application could not promote grains production obviously.Furthermore,it increased amount of top soil nitrate nitrogen significantly,and decreased use efficiency of N and P fertilizer obviously,and promoted the nitrogen accumulation of rice obviously while had no obvious effect on the phosphorus accumulation of rice.Nitrogen and phosphorus accumulation of grains were obviously higher than rice straw,and nitrogen content of grains and rice straw increased with N and P fertilizer application.The use efficiency of N and P fertilizer presented a trend of decrease with the increasing N and P fertilizer application.Treatment with reducing N and P fertilizer application by 15% influenced soil N and P content and grains production scarcely,while the use efficiency of nitrogen and phosphorus fertilizer achieved 43.17% and 48.00% respectively,and decreased the loss risk of nitrogen and phosphorus greatly.Meanwhile,it reduced economic cost,so it's a better model of N and P fertilizer application in rice field of Nansihu basin.