作 者 ：王晓英,贺明荣,刘永环,张洪华,李飞,华芳霞,孟淑华
期 刊 ：生态学报 2008年 28卷 2期 页码：685~694
Keywords:winter wheat, interaction of irrigation and N fertilizer, N fertilizer recovery, soil nitrate-N, grain yield,
摘 要 ：在高肥力条件下，大田试验采用裂区设计，主区为不同灌水频次（0～3次），裂区为不同施氮量（0～240 kg/hm2），结合15N微区示踪技术，研究了水氮耦合对冬小麦氮肥的吸收利用及生育后期土壤硝态氮累积迁移的影响。结果表明，在一定氮肥水平下，不灌水处理的氮肥利用率高于各灌水处理，各灌水处理的氮肥利用率随灌水次数增加呈上升趋势；增加灌水次数，氮肥耕层残留量和残留率显著降低，氮肥损失量和损失率则明显增加。在一定的灌溉水平上，随施氮量（0～240 kg/hm2）增加，植株总吸氮量、氮肥吸收量、氮肥耕层残留量、氮肥损失量以及损失率均呈上升趋势，而氮肥利用率和耕层残留率呈下降趋势。氮肥水平一定时，在灌0至灌2水范围内，籽粒产量随灌水次数增加呈上升趋势，灌3水处理中施氮处理（N168、N240）的籽粒产量较灌2水处理显著降低；灌水生产效率随灌水次数增加显著下降。在一定灌溉水平上，施氮量由168 kg/hm2增至240 kg/hm2，氮素收获指数和氮肥生产效率显著降低，各灌水处理的生物产量、籽粒产量和籽粒蛋白质含量均无显著变化，不灌水处理的生物产量、籽粒产量显著降低。灌水促进了施氮处理（N168，N240）中土壤硝态氮向下迁移，从开花到收获0～100 cm土层中部分硝态氮迁移到了100～200 cm土层。灌水次数是导致收获期0～100 cm土层残留NO-3-N累积量变化的主导因素；水氮互作效应是决定收获期100～200 cm土层残留NO-3-N累积量变化的主导因素，且灌水效应大于施氮效应。
Abstract:The problem of NO-3-N induced groundwater pollution is common in globe including China. The content of NO-3-N in groundwater is seriously affected by excess nitrogen application and irrigation through intensive agricultural practice. However, it has been unclear about the integrated effects of irrigation and nitrogen application on NO-3-N movement across soil profile under high yield condition. In this study, we have designed a special experiment to test different irrigation and nitrogen regimes on the fate of N fertilizer, productive efficiency, and the leaching of NO-3-N from anthesis to harvest of winter wheat in a high fertile soil. The experiment was carried out in a split-plot design, with 4 frequencies of irrigation being in the main plot and 3 doses of nitrogen representing in the subplot. The four irrigation frequencies were arranged as none, once (at elongation stage), twice (before winter and at elongation stage), thrice (before winter, at elongation stage and anthesis stage). The three doses of nitrogen was 0kg/hm2, 84kg/hm2(basal)+84kg/hm2(topdressing at elongation stage), 120kg/hm2(basal)+120kg/hm2(topdressing at elongation stage). The basal nitrogen was applied together with 105kgP2O5/hm2 and 105 kgK2O/hm2 before sowing. Each treatment had 3 replicates, with a plot of 4.5 m×30 m. In one of the three replicates, microplots of 15N tracing experiments were set with the area of 15 cm×44.5 cm, and isolated with a 30 cm high iron frame. Each 15N microplot had 2 replicates, which was added 10.13 atom % 15N -urea as basal application (before sowing) or topdressing. The rates of N application and irrigation frequency in the microplots were the same to these in the field plot. Jimai 20（a winter wheat cultivar with strong gluten）was sowed on 4 October 2003 and harvested on 18 June 2004.
The N fertilizer recovery rate of non-irrigation treatments was found to be higher than those of irrigation treatments. It was noted that irrigation treatments increased the recovery rate along with increased irrigation frequency. Both N fertilizer residual amount and residual rate in plough soil（0-25 cm）layer decreased with increased irrigation frequency, while N fertilizer loss amount and loss rate increased. N recovered by wheat plant, N fertilizer uptake by wheat plant, N fertilizer residual amount in plough soil layer, N fertilizer loss amount as well as loss rate all increased，and N fertilizer recovery rate and soil residual rate both decreased when N fertilizer application amount ranged from 0 to 240 kg/hm2. Grain yield had increased with irrigation frequency which ranged from none to twice, however, it was noted to be decreased in thrice irrigation treatment compared with twice irrigation treatment. Water productive efficiency also decreased with increased irrigation frequency. Biomass and grain yield in non-irrigation treatments, N harvest index and N fertilizer productive efficiency all significantly decreased as N fertilizer application increased from 168 to 240 kg/hm2, nevertheless, there were none significant difference in biomass, grain yield and grain protein content among the irrigation treatments. Irrigation accelerated NO-3-N leaching in N fertilizer application treatments (N168，N240). Dimensionally, the leaching of NO-3-N happened from upper soil (0-100 cm) to deeper soil (100-200 cm) during anthesis to harvest of wheat croping. Our findings suggested that the irrigation frequency was crucial to influence the residual NO-3-N accumulation in 0-100 cm soil profile at harvest. The coupling effect of nitrogen fertilizer and irrigation accessed the process of residual NO-3-N accumulation in 100-200 cm soil at harvest while irrigation played greater role in nitrate movement compared with N fertilizer application.
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