Spatial variation of soil moisture content of a stepped slope under sprinkler irrigation and its affecting factors

In this study, the soil moisture migration pattern was studied under the sprinkler irrigation method with different modes of a stepped slope with 3 steps and its affecting factors. The results showed that at the early stage of the vegetation reconstruction, natural precipitation was enough to ensure the normal growth. This was found valid as long as the soil moisture content (SMC) was higher than 2.45% of the wilting coefficient at the non-irrigation stage. At the non-irrigation stage and at the stage of irrigation once every two days, the SMC increased with depth in the three slope surfaces. However, at the stage of irrigation once daily, the SMC decreased with depth. As the irrigation frequency decreased, the SMC dropped and the coefficient of variation (CV) of SMC rose. The order of CV of SMC within depths in 0-50 cm soil layer was the depths of 40-50 cm > 0-2 cm and 0-20 cm > 20-40 cm. The average soil moisture content (ASMC) increased from the top to the bottom of the stepped slope under different frequencies of sprinkler irrigation. The slope position and hardness and vegetation cover correlated negatively with the SMC (P < 0.01). Whereas, the slope gradient correlated positively with the SMC (P < 0.05).