不同水氮处理对棉田氮素平衡及土壤硝态氮移动的影响

 【目的】探讨不同水氮管理策略对高产棉田氮素平衡及氮素移动的影响。【方法】设置田间小区试验,研究了常规灌水＋常规施氮、优化灌水＋优化施氮、常规灌水＋优化施氮、优化灌水＋优化施氮、常规灌水+不施氮处理条件下的棉田氮素平衡和土壤硝态氮动态。【结果】在常规水氮管理条件下,收获后表观损失量高达163—294 kg?hm-2,60—200 cm土层中硝态氮含量较播前有大幅增加,增量与表观损失的比值达到0.39—0.69;优化水氮管理条件下表观损失量仅为19—87 kg?hm-2;常规水氮处理不同层次土壤剖面上均呈现出硝态氮的积累,而且随灌水量加大累积峰下移,优化水氮管理土壤剖面硝态氮累积程度较小。【结论】在常规施氮体系中氮素的表观损失率达52%—68％,氮素随水移动到根层以下是重要的损失途径之一;本试验中采用的优化水氮管理方法显著减少了硝态氮的淋移损失。

Effect of Different Irrigation and Fertilization Strategies on Nitrogen Balance and Soil Nitrate Movement of High-Yield Cotton System

【objective】 It is of great importance to study the effect of different water and nitrogen management strategies on the nitrogen balance and nitrate movement in soil profile. 【Method】 In a field experiment, the nitrogen balance and nitrate movement in soil profile of conventional irrigation + conventional N application, optimized irrigation + conventional N application, conventional irrigation + optimized N application, optimized irrigation + optimized N application were studied. 【Result】 The result showed that the optimized irrigation and fertilization strategy based on soil nitrate quick testing and soil moister measurement could dramatically reduce N losses from 163-294 kg?hm-2 to 19-87 kg?hm-2. Under conventional treatment, nitrate accumulation were greatly increasing in 60-200 cm soil profile after harvesting, and the ratio of nitrate accumulation amount to apparent N losses within 0.39-0.69. According to the results of nitrate movement process, nitrate accumulation become evident in soil profile of conventional N application, but not evident in optimized one. 【Conclusion】 Apparent N losses can be 52%-68% in conventional N application system, nitrate leaching out of root layer is one of important loss way. Optimized N application system in this experiment can dramatically reduce nitrate leaching.