不同灌溉制度对根层土壤盐分影响的模拟

以河套灌区沙壕渠灌域为例,采用SaltMod模型探讨了不同灌溉制度对作物根层土壤盐分的影响.利用2008-2010年基础资料对模型进行率定和验证并对研究区的根层土壤盐分进行模拟和预测.结果表明:在现有灌排条件下,沙壕渠灌域的盐渍化程度基本达到较为稳定的水平,且有轻微脱盐趋势,未来10 a后作物根层土壤盐分降低3%.生育期土壤水盐垂直交换运动强烈,对于控制土壤盐分而言,灌水量越小越好;作物根层土壤盐分随冬灌灌溉定额的增大而减小,不同冬灌灌溉定额对应的根层土壤盐分最初的增加量均较大,但增加的趋势随时间逐渐降低.根据当地作物种植结构,综合考虑节水灌溉、作物产量和根层土壤水盐环境,建议研究区较优的作物生育期综合净灌溉定额为2 700~3 500 m³/hm²,冬灌净灌溉定额为2 700 m³/hm².

Modeling effects of different irrigation managements on root-zone soil salinity

Taking Shahao canal irrigation region in Hetao irrigation district as an example, effects of different irrigation management on root-zone soil salinity were explored based on the SaltMod model in the paper. The model was calibrated and validated by using the data in 2008-2010, then the root-zone soil salinity in that region was simulated and predicted. The results showed that under the present irrigation and drainage conditions, the soil salinity not only stayed in a stable level, but has exhibited a slightly desalinated tendency, it was predicted that the root-zone salinity would be reduced by 3% after 10 years. During crop growth stage, the exchange between water and salt is remarked in the vertical direction; to control the soil salinity, irrigation water amount should be kept as small as possible. In winter, the root-zone soil salinity was decreased with increasing irrigation quota, but the slope of increase in the salinity was gradually decreased. According to the crop planting structure in a local irrigation district and comprehensively considering water saving irrigation, crop production, water and salt concentrations in the soil of root-zone, it is suggested that optimal irrigation net quota should be 2 700-3 500 m³/hm² in crop growth stage, the quota in winter should be about 2 700 m³/hm².