Effects Of Nitrogen Release From Controlled Release Fertilizer On Yield And Nitrogen Use Efficiency Of Wheat And Maize

In this study, the relationship between nitrogen release of controlled release nitrogen fertilizer for wheat and maize in water at 25 ? and in soil, factors that influence the release under field conditions, and whether nitrogen release from controlled release fertilizer and nitrogen(N) demand of wheat and Maize can be synchronized and its influencing factors was studied. Thus, the theoretical reference for the synchronization of nitrogen release from controlled release fertilizer and nitrogen demand of wheat and Maize, and scientific basis for the technological innovation of slow controlled release fertilizer and the efficient use of economy were provided.Experiments were conducted at Agricultural Experiment Station of Shandong Agricultural University from October 2011 to June 2012,winter wheat- summer maize double cropping was selected, and cultivars of wheat Jimai22 and maize Zhengdan 958 were used. The treatments were no N fertilizer(CK), common urea 100% base used(U1), common urea 50% base+50% jointing stage(U2), base application of the polyolefin-coated urea(PCU), base application of polymer/sulfur coated urea(PSCU), and base application of 50% coated urea+50% common urea(CRU). Effects of application of controlled release fertilizer in maize and wheat rotation on N release, soil N contents, crop N uptake and yield of maize and wheat rotation were studied. The results show as following.Wheat:When equal amount of fertilization used, in the whole wheat growing period, the nitrogen uptake of U2 is 9.01% higher than U1. During the growth period, U2 fertilization treatment on the surface of the soil nitrate and ammonium nitrogen in overall is the highest, the conventional fertilization treatment is the lowest. N release of slow controlled release fertilizer in soil show that the release rate of PCU release rate was slow at the early stage, then released quickly from 40 days after used, and released over 90% on 112 days after used. The release rate of PSCU entered the rapid release period after applied to the soil for 10 days, and released more than 80% on 80 days. The release rate of PSCU is faster than PCU. N fertilization could significantly increase wheat yield, U2 yield was 24.68% higher than CK. The highest yield of U2 was significantly different from other treatment. The N utilization efficiency of U2 treatment was the highest. Two controlled release urea treatments were lower than other treatment. Thus, the N release of controlled release fertilizer was not good enough for wheat than U2.Maize: the N content of maize increased gradually with the growth stage based on the equal nitrogen content in the different fertilization methods. The amount of N accumulation of U2, PCU and PSCU is higher, but that of CK and U1 is lower. The contents of nitrate nitrogen and ammonium nitrogen in the soil were the highest in the U1 treatment before flowering, but those under U2 treatment was the highest after flowering. During the growth period of maize, the cumulative release rates of PCU, PSCU and the nitrogen uptake of maize were linear correlated, and the coefficients reached 0.7727 and 0.7881, respectively, which reached the very significant level. The soil N contents of PCU, PSCU and the nitrogen uptake of maize were also linear correlated, and the coefficients reached 0.7114 and 0.7739, respectively. The yield of PSCU was16.59% higher than CK. The N use efficiency of PCU was 50% and 19% higher than that of common urea U1 and U2 treatment, respectively. The N use efficiency of PSCU was 56% and 27% higher than that of common urea U1 and U2 treatment, respectively.