大棚控制排水对土壤水氮变化的影响

农田排水技术能够解决大棚种植条件下的次生盐渍化问题，因此得到了较广泛的应用。为了分析大棚控制排水条件下的土壤水分和土壤氮素的变化规律，在田间试验的基础上，采用RZWQM（root zone water quality model）模型对不同控制排水处理下的土壤水分含量、土壤氮素含量及氨挥发过程等进行了模拟校正和验证，并利用模型对不同控制排水条件（不同暗管间距和不同控制出口深度）下的水氮变化情况进行了分析。模型在校正阶段的分层含水率模拟均方根误差（RMSE）为0.038～0.050cm3/cm3，验证阶段的分层含水率模拟均方误差（RMSE）为0.040～0.081 cm3/cm3。结果表明：RZWQM模型能够较好的模拟田间水肥变化情况；控制排水对地下水位的控制效果显著但没有对作物的水分利用产生太大影响；不同暗管间距和控制深度下，暗管排水总量、排氮总量和渗漏氮总量都受到了极显著的影响，氮肥利用效率则受暗管间距影响而对控制深度不敏感。

Effects of controlled drainage on soil water and nitrogen changes in greenhouse

The controlled drainage is beneficial to avoiding the secondary salinity in the greenhouse. In order to analysis the soil water and nitrogen dynamics in the greenhouse, the RZWQM (Root Zone Water Quality Model) model was calibrated and validated based on the field experiment and used to analyze the soil water and nitrogen distributions in greenhouse. The root mean standard errors (RMSE) of predicted soil water contents were within the range of 0.038 to 0.050 cm3/cm3 during the calibration and the range of 0.040 to 0.081 cm3/cm3 during the validation. The results indicated that the RZWQM model could be used for the study of water and nitrogen changes in greenhouse field. The controlled drainage had significant effect on the water table depth, the tile drainage volume, tile drainage nitrogen and the seepage nitrogen by the different spacing and depth of underground pipe, on the contrary, the crop uptake was not affected by the controlled drainage.