A point source method for determining the effect of water quality on soil infiltration capability

An automatic soil infiltrability measurement system was applied to measure infiltration processes in laboratory to study the influences of water quality on saline-alkali soil water infiltration by using point source infiltration method.Distilled water and other three irrigation water qualities of EC=2.5,5.0,10.0ds/m at SAR=5(mmol/L)0.5 were adopted in the experiments.Results indicated that the measurement was capable of measuring the complete infiltration process and the method could avoid the soil physical structure damage caused by raindrops hit and fast wetted soil.High salinity of irrigation water was beneficial to soil water infiltration.But the increasing rate of infiltration gradually decreased with the increase of EC.The relationships among infiltration time,maximal vertical wetted distance and accumulated infiltration were a power function at the beginning of infiltration.Both the maximal vertical wetted distance and accumulated infiltration increased with the increasing of salt concentration.After 4h of irrigation,all the accumulated infiltrations of the three saline water levels were greater than that of the distilled water,which the highest being about 2 times of the distilled water.The research results should be significant to salt management for saline-alkali soil.