Abstract:On the earth’s surface, all kinds of soils are always in continuous drying-wetting cycles, which can result in the changes of soil properties. An experiment was conducted to study to the repellent - hydrophilic characteristics of repellent soils in drying-wetting cycles. The results showed that drying-wetting cycles had important impacts on soil-water contact angle and hydrophobicity. When the soil is in drying or wetting, different initial states caused different contact angles. As clay particles increasing, the susceptibility of soil repellency increased to initial states. At the beginning of drying-wetting cycle, the drier sample usually corresponded to the higher contact angle. As water content decreased in loam or clay soil samples in drying-wetting cycle, the WDPT increased and then decreased, and reached the maximum at a certain water content. Under the same water content, the WDPT in drying was significantly lower than that in wetting, there was no threshold water content in the two soil samples. But the WDPT of sand soil samples increased with water content decreasing, no peak appeared in the drying-wetting cycle, and had obvious critical water content.