基于贝叶斯模型平均方法的设施田间土壤氮素运移转化过程研究

The sustainable development of modern agriculture is relied on the high-quality and high-efficiency cultivation in protected field, but is also facing the problems from inappropriate field management and excessive fertilization. The nitrogen enrichment in soil of protected field has been found as a big problem, and is serious threat to the environment of agricultural areas.The key of solution is to throw into the dynamic and spatial characteristics of nitrogen changes in the field, which has also been vital to choose the fit control measures, improve the field nitrogen efficiency, and reduce the pollute to water environment in agricultural areas. This proposal was focused on the study of nitrogen transport process in saturated-unsaturated soil by investigating on the effects from different treatments of irrigation, drainage, and fertilizer in the field, then by the numerical modeling study based on bayesian modeling averaging (BMA) method.The main steps could be described as: Firstly, a physical based model was suggested to build from the existed model and verified by field experiment data; secondly, the dynamic characteristics of model parameters and the weights of processes were studied by the dynamic identifiability analysis (DYNIA) method; after that, the uncertainty of parameters, model structure and data was suggested to investigate by BMA method; lastly, the data-worth of the measured data was suggested to take into account of the simulation of BMA method. After those steps, this proposal will try to give a reliably framework of the modeling of nitrogen process in protected field and make an improve performance on the field modeling of nitrogen conditions. The results are believed to establish theoretical guides to reduce the agricultural pollution and provide an ideal tool in the modeling of nitrogen.

高产高效的设施种植模式为现代农业优先发展方向，但不当田间管理和过量施肥等因素导致了设施田间氮素累积，形成了对农区环境的严重威胁。了解和掌握设施田间土壤氮素状况及其时空变化特征是选择适宜田间调控措施、提高氮素利用效率和减少对农区地表地下水环境污染的关键。本课题主要研究设施环境内灌溉、排水、施肥等田间处理措施对土壤氮素运移过程和转化速率的影响，通过室内外试验研究获取田间土壤主要氮素过程的连续监测数据，建立并验证基于物理机制的设施田间土壤氮素运移转化模型，揭示设施环境内土壤氮素运移转化过程的时变特性与演化规律，深入研究田间土壤氮素模拟的数据、参数及模型结构误差对模型预测的影响，在此基础上提出基于贝叶斯模型平均方法的田间土壤氮素可靠模拟模式。研究成果将对有效评价设施土壤田间氮素状况、合理选择最优田间管理措施和保障设施农业可持续发展提供理论基础和实用工具。

高产高效的设施种植模式为现代农业优先发展方向。设施土壤氮素问题是设施农业可持续发展的重要问题，同时能否有效提高土壤氮素利用效率、减少其对水环境的影响等都是现代农业中日益广泛和迫切需要解决的研究难题，了解和掌握设施土壤氮素运移转化过程是解决设施田间氮素问题的关键。本项目围绕关键科学问题和严格执行研究计划要求，前往武汉大学开展室内人工模拟降雨径流试验和湖北省鄂州市节水灌溉示范基地开展田间试验布置，通过补充完善氮素过程监测数据，深入分析田间灌排条件下水量平衡和氮素运移过程，探索环境影响因子和氮素影响因素对氮素迁移转化过程的影响机理，针对设施耗水量和田间参数等关键影响因素开展了研究，主要取得了以下进展：①项目采用水量平衡分析和田间氮素模拟等方法，针对田间氮素的影响因素和氮素转化子过程开展研究，揭示了氮素转化过程中主要影响变量和模拟参数相互间的影响规律，为设施田间氮素分析提供理论参考；②基于氮素过程和影响因素分析，项目提出了两步制的敏感性分析方法、基于多目标优化框架的氮素模拟模型结构和参数分析法和基于贝叶斯模型平均方法的田间参数分析方法，形成了一套能有效提高田间土壤氮素分析的方法和可靠模式；③研究结果中发现设施耗水量和田间参数对氮素过程影响较大，同时氮素模拟模型中各因素间的相互作用较为明显，因此有必要在对田间因素的分析过程中合理考虑因素相互间影响，同时加强对设施耗水规律的研究；④通过项目研究开发了土壤质地分类工具，可供其他研究者在研究中借鉴；项目中针对作物需水量的分形特征、估算模型的信息特征和模型比较等研究都为该领域的进一步研究提供了新的思路；同时本项目中的环境因子和太阳辐射间的相互关系分析非常深入，有利于其他领域研究者应用。