Study on Saline-alkali Soil Moisture Diffusivity in Da'an Irrigation District

Soil moisture diffusivity is one of the essential parameters to study water and salt motion in saline-alkali soil.The saline-alkali soil moisture diffusivity feature of Da'an irrigation is simulated by horizontal soil column method.The results show that the wetting front migration rate of different soil profile layers is different,but the variation rule is the same;there exists significant negative correlation between wetting front migration rate and time;through fitting analysis,it is found that and the relationship between wetting front migration rate and time is power function;the soil moisture diffusivity is different in different thickness of soil with same volumetric soil moisture content,but not according with the change rule of the gradual increase up to down.The soil moisture diffusivity changes fastest in 40~60 cm layer,then descending as 0~20 cm layer,20~40 cm layer,80~100 cm layer,and the 60~80 cm layer is the slowest.It changes with volumetric soil moisture content in every soil layer as harp positive exponential function,and these relationships are significant with statistical analysis and all of their fitting goodness are above 0.82;soil moisture diffusivity are influenced by soil bulk density and soil salinity.