Soil moisture is crucial for growing trees in dry areas. A study in Shanxi Province looked at how much water Caragana and Pinus trees need compared to wasteland. They found that Pinus trees need 7.8% to 9.7% soil water, while Caragana trees need 7.3% to 11.3%. Both types of trees have dry layers in the soil, but Pinus trees have less impact on soil moisture than Caragana trees. The soil water deficit varies in different soil layers and with different types of vegetation, with Caragana trees having the highest deficit.