Effects Of Controlled-release Fertilizer On Rice Grain Yield And Nitrogen Loss In Paddy Fields

The several field experiments, including different varieties of controlled-release coated urea on the transplanted rice in 2010, controlled-release blending urea (CRBU) on the transplanted rice in 2011 and controlled-release bulk blending fertilizer (CRBBF) on direct seeding rice in 2011 were conducted to investigate the effects of controlled-release fertilizer on rice grain yield and nitrogen loss in paddy fields. The main results were summarized as follows:(1) With 180 kg·hm-2 nitrogen rate, before the flowering stage of the transplanted rice, the application of SPCU (sulfur-polyester resin-coated urea) could reduce the concentration of the total nitrogen, ammonia nitrogen and nitrate nitrogen in the surface runoff and leakagewater, and increase them after the flowering stage compared to PU (prilled urea).(2) With 180 kg·hm-2 nitrogen rate, a higher grain yield of the transplanted rice was obtained when controlled-release coated urea was applied. The highest grain yield occurred after SPCU application, which was 19.7% higher than that in PU fertilizing. The nitrogen use efficiency of SPCU was 39.8%, which showed 22.2% of increment compared with that of PU.(3) With 180 kg·hm-2 nitrogen rate, the grain yield of the transplanted rice with CRBU was 8892.4 kg·hm-2,23.6% higher than PU applied once for all and 14.33% higher than PU applied twice.(4) With 180 kg·hm-2 nitrogen rate, the nitrogen use efficiency of CRBU was 69.96%,49.23% higher than PU applied once for all and 24.20% higher than PU applied twice.(5) The direct seeding rice applied 450 kg·hm-2 CRBBF in seedlings and PU 150 kg·hm-2 after 10-15 days reached highest grain yield of 9071 kg·hm-2.