The study looked at how soil moisture changes in a big gully on the Loess Plateau. They measured soil moisture at different depths over 3 years. They found that soil moisture levels varied depending on depth, with the highest levels at 20-40 cm. When the soil was wet, the variability increased, but it decreased when the soil was dry. Soil particle size and the slope of the land were the main factors affecting soil moisture in the gully.