蓄水坑灌施条件下土壤水氮热耦合效应与机理分析

Water storage pit irrigation is a suitable method for orchard irrigation in arid and semi-arid region of China. Fertilizer will be transported to rhizosphere soil timely and adequately to meet the demands of tree growth while fertilization is combined with water storage pit irrigation, which is of practical significance to improve utilization efficiency of water and fertilizer and protect environment. The transport and distribution characteristics of water and nitrogen in farmland is closely related to soil thermal conditions. Researching the coupled effect and mechanism of soil water, nitrogen, heat under water storage pit fertigation is an important aspect in accelerating the technology development of water and fertilizer coupling and establishing the theory of water storage pit irrigation. Based on the preliminary work, and related to practical situation of orchards in arid and semi-arid region of China closely, experiments on the coupled effect of soil water, nitrogen, heat under water storage pit fertigation will be conducted under conditions with different soil temperature, irrigation water temperature and soil profile temperature gradient. The validity of the coupling effect will be analyzed and the mechanism will be revealed. A mathematical model of the coupled effect of soil water, nitrogen, heat under water storage pit fertigation will be established, and numerical simulation will be carried out usig the model. The results have a significance of scientific value and pratical meaning in developing technology of water and nitrogen coupling, improving fertigation quality, and guiding rational fertigation in orchard.

蓄水坑灌法是一种适合于我国干旱半干旱地区果林灌溉的方法。结合蓄水坑灌溉施（氮）肥，可在灌溉的同时将肥料输送到果树根部土壤，适时适量地供果树生长需求，对于提高水肥资源利用率及保护环境具有重要的现实意义。在灌施条件下农田土壤水氮的运移分布特性与土壤的热状况密切相关，研究蓄水坑灌施条件下土壤水氮热的耦合效应及机理，是加快发展水肥耦合技术、建立蓄水坑灌溉施肥理论的一个重要内容。本项目在前期工作的基础上，紧密结合我国干旱半干旱地区果园实际，拟采用理论分析、试验研究与数值模拟相结合的方法，进行不同土壤温度、灌溉水温、土壤剖面温度梯度条件下蓄水坑灌施的土壤水氮热耦合效应试验研究；蓄水坑灌施条件下土壤水氮热耦合的水氮有效性分析，揭示其耦合机理；建立蓄水坑灌施条件下土壤水氮热耦合作用数学模型并进行数值模拟。研究成果对于发展果园水氮耦合技术、提高灌施质量、指导果园合理灌施具有重要的科学价值和现实意义。

在灌施条件下农田土壤水氮的运移分布特性与土壤的热状况密切相关，研究蓄水坑灌施条件下土壤水氮热的耦合效应及机理，是加快发展水肥耦合技术、建立蓄水坑灌溉施肥理论的一个重要内容。本项目在前期工作的基础上，紧密结合我国干旱半干旱地区果园实际，采用理论分析与试验研究相结合的方法，进行了不同季节果园蓄水坑灌条件下土壤温度的时空变化规律研究，测得不同季节蓄水坑坑内日平均温度变化范围为-5℃～30℃，三个特征时刻（上午8:00，14:00和18:00）土壤温度月平均变化范围为-5℃～35℃；进行了不同土壤温度条件下蓄水坑灌施的土壤水氮热耦合效应试验，研究表明温度是影响土壤水氮运移分布规律的重要因素，试验条件下25℃最有利于铵态氮的硝化。研究成果对于发展果园水氮耦合技术具有重要的科学价值和现实意义。