Abstract: Soil and water conservation measures are essential for preventing soil nutrient loss. However, the mechanisms through which these measures affect soil nutrient loss on slopes in low hilly regions under natural rainfall conditions remain unclear. We examined six measures of soil and water conservation (cross-slope ridge cropping, slope ridge cropping, ridge plant belt, slope terrace, fruit tree terrace, and afforestation) in the Erdaoling small watershed of western Liaoning Province, with fallow bare land as the control. We analyzed the characteristics of soil nutrient loss and the affecting factors under these six soil and water conservation measures. The results showed that: (1) All the six measures of soil and water conservation effectively inhibited nutrient loss, though with varying degrees. Afforestation was the most effective measure for controlling soil nutrient loss, with loss rates of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) being 2.76%, 9.47%, 8.26%, and 4.84%, respectively. (2) Water-stable aggregates and runoff coefficient were key factors affecting soil nutrient loss. The more stable the water-stable aggregates, the smaller the runoff coefficient, and the lower the loss rates of SOC, TN, TP and TK. Soil pH and roughness were significantly positively correlated with SOC loss (P<0.05). The loss rates of TP and TK were correlated with their baseline values and water content. The higher baseline values increased the loss rates of TP and TK, while water content had an opposite effect. Soil bulk density had a significant negative correlation with TK loss (P<0.05). Overall, soil nutrient loss on slopes in the low hilly regions of western Liaoning was affected by a variety of factors. Afforestation was the optimal management strategy for reducing nutrient loss and should be prioritized in the ecological restoration of sloping cultivated lands in small watersheds in this region.

Key words: natural rainfall, soil and water conservation measure, soil nutrient loss, influencing factor