Effect of the number of years of vegetable cultivation on soil phosphorus sorption-desorption characteristics

An experiment involving 3~5, 15~20 and 25~30 years continuous vegetable cultivation was carried out to determine fixation and release mechanisms of soil phosphorus in cultivated yellow brown soils. Based on the results, phosphorus isothermal adsorption and adsorption-desorption curves are respectively described by Langmuir equation and quadratic equation. With increasing years of cultivation, the maximum phosphorus adsorption (Q_m) and maximum buffer capacity (MBC) of surface soil decrease significantly. However, degree of phosphorus saturation (DPS) and phosphorus desorption rate increase. Phosphorus desorption rates in 15~20- and 25~30-year cultivated vegetable soils are significantly higher than that in the 3~5-year cultivated vegetable soils. Correlation analysis for the main factors affecting soil phosphorous adsorption-desorption (e.g., MBC, DPS, etc.) reveals that soil amorphous Fe-Al content significantly affects soil phosphorus adsorption-desorption.