Acidity regime of the Red Soils in a subtropical region of southern China under field conditions

The southern Lake Tai area is an important agricultural area distributed with 500,000 ha of paddy soils. Based on the current soil phosphorus status, it is predicted that phosphorus in agricultural runoff from paddy fields is now one of the most dangerous threats to the quality of water in Lake Tai and the application of phosphorus fertilizers should be controlled. Phosphorus adsorption maxima based on the Langmuir equation were calculated for various soil-environmental conditions and the upper limit of accumulative phosphorus application to paddy soils of the area is suggested