漫灌和喷灌条件下土壤养分运移特征的初步研究

用非饱和土壤溶质运移的对流扩散方程及其解析解，联系大田漫灌、喷灌的入渗实际，在室内试验的基础上，研究了漫灌、喷灌入渗条件下，土壤养分运移的特征。研究结果表明，阳离子Ｋ^＋，由于土壤颗粒的吸附作用，流动性差，入渗结束后，Ｋ^＋浓度集中分布在土表０～２０ｃｍ土层内。阴离子ＮＯ₃^-，流动性强，入渗方式对ＮＯ₃^-离子运移影响大。漫灌入渗条件下，孔隙水流速度大（是喷灌的３．５倍），ＮＯ₃^-运移快，机械弥散作用是喷灌的１１．６倍，入渗结束后，ＮＯ₃^-浓度集中分布在土壤深层的作物主根区之外，不利于作物吸收利用，并容易造成地下水污染。而在喷灌入渗条件下，供水强度低，孔隙水流速度小，ＮＯ₃^-运移慢，弥散作用弱，入渗结束后，ＮＯ₃^-浓度的峰值迁移浅，ＮＯ₃^-浓度集中分布在土壤表层作物主根区内，有利于作物吸收利用。这正是喷灌节水、保肥的内在机理。

Preliminary Study on Soil Solute Transport Under Sprinkler and Flood Irrigation

Based on the unsaturated soil solute transport equation-the Convection Dispersion Equation, and its analytical solution and lab experiment, the characteristics of soil solute transport was studied under sprinkler irrigation and flood irrigation. The result showed that the main concentration of K⁺ was distributed within 20 cm of soil surface with flood and sprinkler irrigation because of the soil adsorption. Under flood irrigation, the pore water velocity was great,NO₃^- transported quickly, the dispersion strong and NO₃^- concentration mainly distributed out of root zone after irrigation, which was not convenient for crop uptake and eased to pollute under grounder water. Under sprinkler irrigation, the intensity of water supply was low, the pore water velocity small, the dispersion weak and NO₃^- transport slowly, which leaded to NO₃^- distribution within surface soil and convenient for crop root uptake. It is the key reason why sprinkler irrigation saves water and keep on fertilizer.