Soil phosphorus status under restored plant covers established to control land degradation in the red soil region of South China

Irrational exploitation has brought about serious consequences causing severe soil erosion and loss of soil productivity in the red soil region of China. Different vegetation systems were thus established for soil conservation. Five systems—composed of eroded area (Er), bamboo (Bmb), Chinese fir (CF), citrus orchard (Ctr), and rice field (Rf)—were studied to monitor the status of phosphorus in their ecosystems. Generally, soil P was concentrated in the surface soil layer. The rank order for soil total phosphorus and microbial biomass phosphorus in the surface layer was: Rf > Ctr > Bmb > CF > Er and Bmb > CF > Ctr > Rf > Er, respectively. Among the established vegetation covers, external nutrient input had intensely contributed to the buildup of soil P status as systems receiving manure or fertilizer (Bmb, Ctr and Rf) and showed considerably higher P level in their profiles as compared with their forest counterpart (CF). The amount of total P lost from the soil by erosion depended mainly on the mass of soil eroded, mainly via particulate forms. The level of soil erosion was the highest in Er, followed by CF > Ctr > Bmb, and the amount of total P loss by soil erosion in descending order was the same: Er > CF > Ctr > Bmb. All these indicated that vegetation covers reduced soil erosion and nutrient loss significantly.