Effects Of Different Amounts Of Pesticide And Agronomic Practice On Yield And Nitrogen Use Efficiency Of Rice

The average N application rate for rice production in China is180t ha-1, which is about75%higher than the world average. Excessive utilization of nitrogenous fertilizer will not only lead to a lower nitrogen use efficiency, but also cause many environmental problems. Excessive application of pesticides will also cause many big environmental problems, and will be potentially harmful to the farmers. Therefore, increase nitrogen use efficiency and reduce application of pesticides are two major task for rice production in China.The experiment was conducted in two experimental sites (zhougan and zhangbang village, Wuxue city) with the same treatments. The main plots were two pesticide treatments (CK and PDT), and the sub-plots were six agronomic management practices (N0, FP, OPT1, SHY, OPT2, HFF). In this study, fertilizer and cropping systems management were integrated into a comprehensive management framework, and both N efficiency and rice yield were investigated. The main results are as followings;(1) In the CK pesticide treatment of zhougan village, the grain yield of HFF, SHY, and OPT1treatments were10.08,9.84and9.61t ha-1, respectively, and were significant higher than other treatments. Compared with FP treatment, they were increased by13.1%,10.9%and8.8%, respectively. In the CK pesticide treatment of zhangbang village, the grain yield of HFF treatment was the highest (9.67t ha-1), which was increased by11.2%compared with FP treatment.(2) In the PDT treatment of zhougan village, the grain yield of HFF, SHY, and OPT1treatment were9.57,9.14and9.14t ha-1, respectively, and were also significant higher than other treatments. Compared with FP treatment, they were increased of13.1%,10.9%and8.8%, respectively. In the PDT pesticide treatment of zhangbang village, the grain yield of HFF treatment was also the highest, reaching9.41t ha-1.(3) In the CK treatment, the agromonic nitrogen use efficiency of HFF treatment in zhougan village and zhangbang village were66.4%and53.1%higher than the corresponding FP treatment. The recovery nitrogen use efficiencies of HFF treatment in the zhougan and zhangbang villages were78.8%and77.3%, respectively, and were significantly higher than other treatments. In the PDT pesticide treatment, the AEN and REN of HFF treatment in the two sites were also the highest.(4) In the CK and PDT pesticide treatment, the spikelets (m-2), newly assimilated dry matter during ripening, and the N content (g m-2) of maturity in HFF treatment in the two sites were much higher than other treatments. These were attributable to the ability of HFF to gain much more grain yield and higher N use efficiency than other treatments.(5) Compared with the two pesticide treatments in the two sides, we found that the average grain yield of PDT treatment was4.2%lower than CK treatment in zhougan village and5.2%lower in zhangbang village. We also found that the AEN of PDT treatment was26.2%lower than CK treatment in zhougan village and17.6%lower in zhangbang village.