Properties of runoff, sediment and soil carbon stock under different soil and water conservation measures in sloping farmland

By using standard runoff plots observation method, under the natural rainfall condition, this paper studied the properties of soil and water loss and organic carbon loss under different soil and water conservation measures in the Yizhe small watershed area in Kunming. The results were as follows:(1) As the important carrier of soil organic carbon, the loss of sediment-bonded soil organic carbon accounted for over 82.0% of the total organic carbon loss with runoff, and the maximum proportion could reach 97.33%. (2) Compared with CK, these vegetation cover and reverse-slope level terrace measures had great effects on promoting soil and water conservation and on reducing the runoff and sediment. The reduction rate of runoff by the two measures were 94.47% and 61.70% respectively, and sediment reduction rates of them were 94.81% and 64.80% . (3) Compared with CK, the two measures could reduce the loss of soil carbon storage, and could mitigate the negative effect of soil carbon storage to some extent as well. The reduction rate of soil carbon storage of CK was 14.39% through the rainy season, which was significantly higher than those of vegetation cover and reverse-slope level terrace measures with the reduction rate 3.83% and 6.25% respectively. The results suggested that the soil and water conservation measures had remarkable effect on reducing the loss of soil organic carbon on the slope mainly by changing underlying surface and microtopography of the land surface, interrupting runoff on the slope and reducing the sediment and nutrient elements by the runoff and sediment.