温度对南方红壤和水稻土水分特征曲线影响差异性分析

Difference Analysis of Temperature Effect on Water Characteristic Curves of Red Soil and Paddy Soil in South China

为了研究温度变化对土壤水分特征曲线的影响,采用高速离心机法测定南方红壤和水稻土在4,12,20,28,36℃温度条件下土体脱湿过程的水分特征曲线,并运用VG模型进行参数提取,探讨了温度对土壤当量孔径分布、非饱和导水率及水分扩散度等参数的影响。结果表明:相同水势条件下红壤和水稻土的含水率随温度增加而显著减少(P<0.05),表现出4℃>12℃>20℃>28℃>36℃的关系,且同一温度下的红壤持水性能显著高于水稻土(P<0.05);不同温度处理下红壤和水稻土的非饱和导水率以及水分扩散度均表现出20℃最高、36℃最小的显著差异性(P<0.05),这表明土壤在20℃时的导水能力和入渗能力相对最佳,且同一温度下红壤的非饱和导水率和水分扩散度均低于水稻土;红壤和水稻土的饱和含水率θs、进气值相关参数α、形状系数n均随温度增加而缓慢减小,拟合参数随温度变化而差异显著(P<0.05),这说明土壤水分特征曲线参数对温度有一定的敏感性。研究结果可为进一步探讨温度对南方土壤持水性能和水分运移机制研究提供合理的参考依据。

In order to study the effect of temperature changes on soil water characteristic curve,the water characteristic curves of red soil and paddy soil in South China were measured by high-speed centrifuge at 4,12,20,28 and 36℃respectively.The parameters were extracted by VG model,and the effects of temperature on soil equivalent pore size distribution,unsaturated hydraulic conductivity and water diffusivity were discussed.The results showed that the water contents of red soil and paddy soil decreased significantly with the increase of temperature under the same water potential(P<0.05),appearing as 4℃>12℃>20℃>28℃>36℃.The water holding capacity of red soil was significantly higher than that of paddy soil(P<0.05)at the same temperature.Under different temperature treatments,unsaturated hydraulic conductivity and water diffusivity of red soil and paddy soil showed the significant difference that the highest value was observed at 20℃and the smallest at 36℃(P<0.05),which indicated that the water conductivity and infiltration capacity of red soil were relatively optimal at 20℃.The unsaturated hydraulic conductivity and water diffusivity of red soil were lower than those of paddy soil at the same temperature.The saturated moisture contentθs of red soil and paddy soil,the relative parameters of air intake valueα,and the shape coefficient n all decreased slowly with the increase of temperature,and the fitting parameters were significantly different with the changes of temperature(P<0.05),which indicated that the parameters of soil water characteristic curve were sensitive to temperature.The results of this study could provide a reasonable reference for further exploring the effect of temperature on soil water holding capacity and water transport mechanism in southern China.