Evaluation Of Nitrogen Loss Way, Water And Nitrogen Use Efficiencies In Winter Wheat And Summer Maize Rotation Syste Under Different Fertilizer N Managements

Using field experiment combined water and nitrogen (N) management model (WNMM), the nitrogen loss, the eco-environmental effect, the soil water and nitrogen behaviors under six kinds of nitrogen fertilizer management practices in high yield production area of Huantai County in Shandong province were systematically studied. The objectives of the paper were to evaluate the agronomic and environmental effects under different management practices and to determine the optimal N management practice. The main results are as follows: The yield for CRF was 8632 kg hm^-2 and was the highest in the maize growth season .The order of the yield under the other treatments was following as: OPT >CRFM >FP >OPTM. The yield for CRFM was 6369 kg hm^-2 and was the highest in the wheat growth season .The order of the yield under the other treatments was following as: OPT >FP >OPTM >CRF. The OPT and CRT treatments both could increase grain yield, and the difference among the six fertilizer treatments was not significant.Soil water storage of in 1.8 m-soil profile on the end of the wheat growth season was lower than that on the beginning of the maize growth season. The difference among different fertilizer treatments was not significant.The accumulative nitrate in 1.8 m-soil profile after wheat harvest in 2010 was lower than that of before maize sowing in 2009, except for CRFM. During the maize growth season, the substantial amount of NO₃^--N under FP accumulated in soil layer of 70cm to 160cm, especially 120-140cm; the amount of NO₃^--N under OPT and OPTM accumulated in soil layer of 100cm to 160cm, especially 110-130cm; the amount of NO₃^--N under CRFM and CRF accumulated in soil layer of 60cm to 180cm. During the wheat growth season, the amounts of NO₃^--N under OPT, OPTM and CRF reduced to 35%, 59% and 70% of FP.Based on field experiment, water and N management model (WNMM) was calibrated and validated, the results indicated that the simulated soil water content and nitrate content were both agreed well with the measured values. Thus, the model could be used to simulate the soil water and N transport in the study area.During the maize growth season, the main sources of water loss were evapotranspiration and leakage, the difference of evapotranspiration among the six fertilizer treatments was not significant and the leakage of water under OPT was the lowest; The results indicated that the ratio of nitrate leaching and NH3 volatilization accounting of fertilizer N ranged from 6% to 18% and 5% to 34%, respectively, and the amount of N leaching under OPT was 14.5 kg hm^-2, was the lowest in all treatments, but the amount of NH3 volatilization under CRT were 7.6 kg hm^-2, respectively, was the lowest in all treatments. During the wheat growth season, the main source of water loss was evapotranspiration, and the results indicated that the ratio of NH3 volatilization accounting of fertilizer N ranged from 7% to 16%. The order of total N loss under six treatments was following as: FP > OPT >OPTM >CRFM >CRF>CK.The OPT and CRT treatments both are the best management practices considering their high grain yield, water and nitrogen use efficiencies, and environmental protection.