温室土壤硝态氮积累的温度、水分、施氮量耦合效应

Effects of moisture, temperature and nitrogen supply rate on NO_3^-N accumulation in greenhouse soil

为了探讨温室作物生产水肥管理和土壤温度对土壤硝态氮累积的影响,本文选取使用5年的温室土壤样品进行培养试验,研究温度、水分、施氮量及其耦合效应对温室土壤硝化作用和硝态氮累积的影响。试验结果表明:温室土壤硝态氮累积量可用"S"曲线进行定量描述,硝化过程中最大硝化速率、延迟期和最大可能累积量是参数土壤温度,含水率和NH4-N含量的函数;通过正交回归分析得出影响最大硝化速率的因素主次顺序依次为温度、含水率、温度与含水率的交互作用、水肥的耦合作用以及施氮量;影响延迟期的因素主次顺序依次为土壤水分、土壤温度、施氮量以及水肥耦合作用;最大可能累积量与温度、含水率及施氮量呈指数关系,其中施氮量影响最大,土壤温度次之,而这3个因素之间的交互作用对最大可能累积量没有明显的影响。利用回归模型,可为不同温度环境及水肥条件下硝态氮累积量及氮利用的有效性预测提供依据。

In order to ascertain that the soil water, fertilizer and temperature management affect on the NO3^- -N accumulation of soil in greenhouse crop production, an incubation experiment was conducted to determin the changes of NO3^- -N accumulation with time during the process of nitrification under various soil moisture（W）, soil temperature（T） and nitrogen supply rate（N0） for 5 years greenhouse soil. The results indicated that equation Δ（NO-3）=e（a＋b/τ） could be used to express the NO3-N accumulation with time. The maximal rate of nitrification, delay period and maximal NO3^- -N mass of accumulation were derived from the equation, and used to characterize quantitatively the nitrification process in different soil conditions. The effect on maximal rate of nitrification Kmax was a descending order of soil moisture, soil temperature, interaction of temperature and moisture, interaction of moisture and nitrogen supply rate, and nitrogen supply rate, and the effect on delay period was a descending order of soil moisture, soil temperature, nitrogen supply rate and interaction of moisture and nitrogen supply rate. Maximal NO3^- -N mass of accumulation depended on nitrogen supply rate, moisture and temperature, and did not affect significantly by their interactions. In greenhouse production systems, where moisture and temperature can be controlled, this model can be used to predict NO3-N accumulation and the effectiveness of N in the fertilizer management that considers both nitrogen supply rate and soil environment.