Time‐dependent effects of ecological rehabilitation on soil phosphorus fractions on cut slopes in the mountains of Southwest China

Abstract

AbstractWhen a cut slope is excavated, the ecological environment in the footprint is destroyed. Soil spray seeding technique is used for the ecological rehabilitation of cut slopes in the mountain areas of Southwest China. However, there have been few studies of the temporal variation in soil phosphorus (P) fractions during the rehabilitation of the cut slopes. In this study, time‐dependent changes in soil inorganic P (Pi) and organic P (Po) fractions of the cut slopes were assessed at selected post‐rehabilitation ages (i.e., 1 year, 1a; 3 years, 3a; 5 years, 5a; and 11 years, 11a). The results showed that the amounts of Pi and Po fractions in soils on rehabilitated cut slopes varied with time. The reduction in the total Po (TPo) content was mainly caused by the change in high concentration hydrochloric acid‐soluble Po (HHCl‐Po) in the soil. The reason for the highest TP content in 3a was the addition of inorganic fertilizer and straw in the artificial soil. The analyses of Pearson correlation and multiple stepwise linear regression showed that TPo and N:P were the main factors affecting the availability of soil P. With the increase in the post‐rehabilitation age, the limitation of soil P gradually weakened, but nitrogen became one of the limiting factors for plant growth. Overall, soil nutrient monitoring is very important for vegetation restoration of the cut slopes. Applying organic fertilizer after 5 years of ecological rehabilitation is conducive to long‐term supply of nutrients required for plant growth.