基于15N示踪技术的不同灌水方案玉米追肥氮素去向研究

为了揭示不同灌水方案下玉米对追肥氮素的吸收利用情况，利用15N示踪技术，以大田试验数据为基础，研究了不同灌水方案下成熟期玉米对追肥氮素的吸收利用率以及在地上部各器官中的分配状况，同时研究了玉米收获后追肥氮素在土壤中的残留情况和最终的损失率。结果表明：不同灌水方案下玉米地上部分氮素总积累量的8.14%~13.21%来自于追肥氮素，各处理之间差异显著（P<0.05），其中籽粒中追肥氮素积累量占植株积累追肥氮素总量的47.90%~74.40%。不同处理下成熟期玉米植株追肥氮素吸收率为19.16%~64.72%，其中籽粒的追肥吸收率为11.29%~47.17%。植株积累的追肥氮素在各器官中的分配比例差异较大，其中，47.95%~74.40%分布在籽粒中，10.50%~27.73%分布在叶片中，3.02%~9.48%分布在茎秆中，5.22%~15.53%分布在穗轴中，苞叶中仅占0.53%~2.35%。在玉米生育前期灌水量过大而后期缺水会对植株吸收追肥氮素以及氮素向籽粒中再分配产生不利影响，同时单次灌水量过大产生氮素的淋溶损失，造成资源的浪费和环境的污染。玉米收获后有8.81%~24.89%的追肥氮素残留在土壤中，随灌水次数的减少，单次灌水量增加，追肥氮素残留率逐渐减小。综合考虑产量和追肥氮素利用率，得出符合研究区玉米节水、高产、高效要求的灌水方案为全生育期灌溉定额800m3/hm2，灌水次数为4次（苗期、拔节期、抽雄期、灌浆期），研究结果可为东北地区玉米生产提供理论支持及数据参考。

Fate of Maize Topdressing Nitrogen under Different Irrigation Schemes Based on 15N Tracer Technology

In order to reveal the absorption and utilization of topdressing to maize under different irrigation schemes, 15N tracer technology was used based on field test data, the ratio of absorption and utilization to topdressing was analyzed and the distribution of fertilizer nitrogen in the upper parts of maize under different irrigation schemes, and the residue in the soil and final loss rate of nitrogen after harvest were studied. The results showed that 8.14%~13.21% of total nitrogen accumulation in maize aboveground parts came from topdressing under different irrigation schemes, there was a significant difference between the treatments (P<0.05). Among them, topdressing nitrogen accumulation in the grain accounted for 47.90%~74.40% of the total topdressing accumulation. The nitrogen recovery rate of top dressing was 19.16%~64.72% under different treatments, and the recovery rate of grain topdressing was 11.29%~47.17%. The proportion of topdressing nitrogen in different organs was different, the distribution of 47.95%~74.40% was in grain, 10.50%~27.73% was in leaves, 3.02%~9.48% was in stem, 5.22%~15.53% was in spike axis, and only 0.53%~2.35% was in coating. In the early stage of maize growth, the irrigation amount was too large and the water shortage in the later period would have a negative effect on the absorption of nitrogen in the plant and the redistribution of nitrogen to the grain. At the same time, the amount of single irrigation was too large, resulting in the leaching loss of nitrogen, waste of resources and pollution of environment. After harvest, there were 8.81%~24.89% topdressing nitrogen residue in the soil. With the decrease of irrigation frequency and increase of single irrigation amount, the nitrogen residue rate of topdressing was decreased gradually. Considering yield and fertilizer utilization ratio, the irrigation scheme which met the requirements of water saving, high yield and high efficiency in this area was 800m3/hm2 of irrigation quota and four times of irrigation (seedling, jointing, tasselling and filling), the results can provide theoretical support and data reference for maize production in Northeast China.