Adding clay to sandy soil in Inner Mongolia affects how quickly water evaporates from the soil. The more clay added, the longer it takes for water to evaporate. In the first stage, adding more clay reduces the rate of evaporation, but in the second stage, it increases the amount of water evaporated. Soil with added clay retains more water after evaporation compared to soil without clay. The study found that the relationship between clay content and evaporation is complex, with different effects at different stages of the process.