Effects Of Organic-mineral Cimpond Coated Urea On Nitrogen Utilization Efficiency

In this study, we determined the amounts of NH3 volatilization, nitrate leaching and residual urea from 3 newly created controlled release ureas(CRU) in sandy soil and black soil in laboratory, and investigated their effects on nitrogen utilization efficiency(NUE), on yields of soybean and rice, as well as on quality of soybean by ?N tracing pot culture and plot experiment. The main results obtained are as following: 1. All of the 3 controlled release urea(referred as CRU1, CRU2 and CRU3) decreased the amount of NH3 volatilization in sandy soil and black soil, and the decrease ranges for CRU 1, CRU2 and CRU3 were 33.3%, 2.5% and 15.13% compared with common urea in sandy soil, and 42.6%, 37.3% and 39.9%, respectively in black soil; 2. The N losses through nitrate leaching were reduced markedly in sandy soil by application of controlled release ureas compared with common urea, and the reduced percentages for CRU1, CRU2 and CRU3 were 36.06%, 15.49% and 30.03%, respectively; 3. Incubation experiment in the laboratory showed that there was more urea which was kept in CRU treated soils than in common urea treated soils, and the highest residual urea occurred in CRUI treated soils. The amount of residual urea was higher in black soil than in sandy soil; 4. The nitrogen utilization efficiency was improved by application of CRU. The NUE of CRU in soybean was increased by 11.33%, 3.06% and 5.59% compared with common urea treated soybean. The corresponding values were 3.64%, 19.92% and 10.53% in rice. For soybean, CRU 1 was the best, and for rice, CRU2 gave the best results; 5. CRUs significantly increased the 100-grain weight of soybean and 1000-grain weight of rice, and therefore increased the yield of soybean and rice. In pot culture experiment, the yield increases in CRU treated soybean were 49.22%, 37.48% and 22.56% compared with CK, F=23.90>F001=6.99 In plot experiment with soybean, the yield increased by 15.8%, 6.83 % and 6.63 % compared with CK, F=7.73 >F005 =4.76 In pot cultured rice, the yield increases were 34.59%, 18.56 % and 8.66 % compared with CK, F88.49 >F001 6.99; 6. CRU application increased the protein content of soybean as well, F=9.88>F001=6.99 indicating that CRU can improve soybean quality.