Effects of long-term fertilization on phosphorus adsorption and desorption in purple soil

Characteristic of phosphorus sorption and desorption in purple soil about long - term different fertilization and rotations was studied. The results showed that the curve of P adsorption raised precipitously in the low P concentration, the curve became slack and soil ad sorption capacity weakened gradually as phosphorus concentration rising. Soil adsorption slowed down as P concentration in the solution was 20mg/L and 60mg/l., in the way of rice-rape rotation. P concentration 60mg/L of the solution was the change-point of soil adsorption in rice-wheat rotation. It was easier to cause P loss in using cow manure than other fertilizers and cow manure increased risk of P loss. The ratio of desorbed P was lower 10.3%-68.9% in rice-wheat rotation than in rice-rape rotation according to the ways of cultivation.