控释肥对土壤氮素迁移转化的阻控和调节机制研究

The controlled-release urea has excellent controlled release performance, and plays an important role in regulating the supply of nitrogen in the root layer, reducing nitrogen loss, and improving the nitrogen use efficiency. The core effect of controlled-release technology is to regulate the transfer and transformation of fertilizer nitrogen in soil. However, how it regulates the release of soil nitrogen and the related mechanism were not still understood until now. In this study, we try to quantify the disturbing activity of applying controlled release urea on soil nitrogen pools, the capacity of applying controlled release urea on inhibiting soil nitrogen loss flux, and the spatio-temporal coupling relationship between the controlled release urea and soil in soil nitrogen migration transformation process as compared with the urea. Soil nitrogen primary transformation rate and the nitrogen loss flux are measured by using 15N isotope tracer, the spatio-temporal distribution of nitrate in fertilizer microsites are measured by using mid-infrared attenuated total reflection spectroscopy, and conventional methods are used to determine the content of nitrogen in soil after fertilization. Comprehensive analysis will be done to quantify the nitrogen transformation process of fertilizer in the soil. The aim of this project is to clarify the impact of controlled release urea on soil nitrogen transformation process and the nitrogen balance, to explore the influence of controlled release technology on the matching mechanism of fertilizer-soil-plant and their coupling relationship no matter in time and space, The mechanism of the effects of controlled release urea on soil transfer conversion process will be revealed for the controlled release urea production, and to provide theoretical support for the production and use of controlled-release fertilizer.

控释氮肥能简化根层定量调控施肥技术，在调节氮素供应、损失和提高肥效等方面有着重要作用。控释技术的核心作用是调控肥料氮在土壤中的迁移转化过程，但控释行为对土壤氮素的阻控、调节作用的强度并不清楚。为此，本研究以土壤氮素迁移转化过程为对象，在施用控释尿素和普通尿素两种情况下，开展控释氮肥对土壤氮库容扰动、氮素损失阻控及其与植物-土壤氮素耦合关系的研究。拟采用15N同位素示踪技术研究土壤氮素初级转化速率和土壤氮素损失通量、中红外衰减全反射光谱研究硝态氮在肥际的时空分布，常规方法研究施肥后土壤氮素形态含量，将控释和非控释行为下的土壤氮素转化过程定量化。并通过比较两种施肥方式下的土壤氮素特征，阐明控释氮肥对土壤氮素迁移转化和氮素平衡的扰动作用，对土壤氮素损失的阻控作用，肥料氮-土壤氮-植物氮在时空上的匹配与耦合关系。揭示控释肥料对土壤氮素迁移转化过程的影响机制。为控释肥的生产使用提供理论支撑。

控释尿素能够控制养分释放满足作物全生育期的养分需求，促进作物养分吸收，并且减少环境污染，是肥料研发的热点。但控释尿素对土壤氮素调控的作用强度、对土壤氮素迁移的调节机制还不清楚。为了阐明控释技术在土壤-植株系统中所发挥的作用机制，科学评价控释尿素在玉米上的田间应用效果，本研究在河北省曲周县开展了两年的玉米田间试验，研究了施用控释尿素对不同时期土壤无机氮及植株氮素吸收动态、土壤无机氮时空分布、农田氨挥发和N2O排放损失、土壤-植株氮平衡、产量、及经济效益的影响。主要的研究结果如下：.施用控释尿素能够维持不同玉米生育时期耕层无机氮含量，提高收获后0-40 cm无机氮含量，普通尿素处理的0-20 cm、20-40 cm土壤无机氮含量低于控释尿素处理39.7%、41.6%。一次性施用控释尿素能够满足玉米整个生育期的氮素需求。普通尿素处理在施肥后1-2周内，快速水解释放，在施肥中心附近呈现较高的无机氮浓度，控释尿素能够控制氮素养分的释放，施肥后不会引起施肥点周围无机氮浓度在短时间内快速升高。.施用控释尿素能够减少基肥后氨挥发量54.4%、追肥后氨挥发量57.4%；在玉米整个生育期内减少N2O排放量68.8%。土壤-植株氮平衡结果表明施用控释尿素可提高植株氮素吸收9.9%，减少活性氮素损失35.5%，减少氮素盈余量13.0%。施用控释尿素能够优化土壤-植株氮平衡。.两年平均结果来看，施用控释尿素提高了玉米产量8.0%，提高了氮肥利用率10.6%。CRU90处理的氮肥农学效率、氮肥偏生产力分别高于U处理28.5%、9.6%。CRU90处理氮肥利用率显著高于SF处理11.7%。CRU90处理是本研究最优的处理。通过一次施用控释尿素，可节约劳动力成本，获得了较高的产量效益，每公顷增加净收益2514.6元。.综上所述，控释尿素能够以特定释放规律释放氮素养分，促进氮素供应与作物氮素养分吸收相协调，减少对无机氮库的扰动作用，将更多的氮素阻控在土壤-植株系统内，减少活性氮素损失，由此促进了玉米氮素吸收，提高玉米产量和净经济效益。施用控释尿素可以作为一种有效的氮素管理措施解决氮素管理中的问题，协调作物高产和环境污染这对矛盾。