Abstract: The phosphorus pools of seven calcareous soils were characterized by using ³²P isotope kinetic approach. Through the determination of residual radioactivity in soil solution at different time after the introduction of the isotope to the steady soil-water system, a well-defined isotope kinetic model was obtained by which the mean sojourn time of phosphate in solution (T_m), the mean exchange rate(K_m),and the mean flux (F_m)of phosphate ions between solid and solution can be calculated. Other parameters such as the exchangeable P of the first minute(El), P in various pools that could be exchanged with solution phosphate ions at different period of time were also calculated. These parameter were further compared with other conventional P indices such as E value,A value and OIsen-P as well as ryegrass uptake of P. Results indicated that the above parameters and indices were highly correlated with one another. It is suggested from the study that the isotope kinetic approach could be used to characterize soil available P pools.

Key words: Calcareous soil, Isotope, Kinetics, Phosphorus

CLC Number: 

• S153