不同负压灌溉条件土壤水分运移规律研究

Research on Soil Water Migration Rule under Different Negative Pressure Irrigation

基于室内模拟实验,研究了不同负压(0、-5、-10、-15、-20 k Pa)灌溉条件下土壤水分的运移规律。研究结果表明:不同负压条件下的负压灌溉湿润体均为近似椭球体,其水分入渗量及湿润锋的运移均与时间呈显著幂函数关系(Y=a X^b),相关系数在0.99以上,入渗速率随负压绝对值增大而减小,-5 k Pa处理的渗水速率为对照的80%,-10 k Pa处理为对照的67%,-15和-20 k Pa处理均为对照的57%。湿润锋水平和垂直运移速度随负压绝对值增大而降低,与对照相比,-5 k Pa处理的垂直湿润锋延迟2 d到达箱底,-10 k Pa处理延迟5 d,-15 k Pa处理延迟8 d,-20k Pa处理延迟12 d。土壤含水量变幅随着控制水势下降而增加,下限土壤含水量减小。

Soil moisture migration rules under different negative pressure irrigation are studied based on the indoor experiments. The results indicate that the geometry of the wetted soil under negative pressure irrigation can be best represented by a truncated ellipsoid; both the cumulative infiltration and migration of wetting front have the significant power function relationship with time with R is more than 0.99; the infiltration ration decreases with the increase of the absolute pressure value, the infiltration ratio of the -5 kPa treatment is 80% of CK, the infiltration ratio of -10 kPa is 67% of CK and the infiltration ratio of -15 kPa treatment and -20 kPa treatment is 57%; the horizontal and vertical migration speed of wetting front decrease with the increase of the absolute pressure value; comparing with control, the vertical wetting front of -5 kPa treatment delays 2 days to reach the bottom, the -10 kPa treatment delays 5 days, the -15 kPa treatment delays 8tdays and the -20 kPa treatment delays 12 days; with the decrease of the water potential control, the soil water content changing range increases, while the lower limit of soil water content decreases.