Abstract
For the development of soil and plant phosphate (P) model, the soil labile-P values are required in addition to fertilizer P availability indices. This study was conducted to determine the relationship of labile-P (IRA-400 anion exchange resin, NaHCO3 form) with a routine Olsen-P (NaHCO3 extractant) method in order to develop predictive equations for labile-P. Nineteen alkaline surface soils representing a wide range of properties with initial P treatment at the rate of 0, 30, 60, and 90 mg P kg-' soil were used in laboratory experiment for a 7-day and a 6-month incubation period. Labile-P (Pa) and Olsen-P (0P) increased with increased P rates. Pp, related linearly to OP values at all P rates, showing a decreasing trend in correlation coefficient (r = 0.877" - 0.751" with a 7-day incubation; r = 0.856" - 0.643" with a 6-month incubation) with increased P rates. After a 7-day incubation, about 77% of variation in At were explained by the regression equation and it decreased to 50% at higher P rate. Both incubation periods showed similar relationships , indicating the feasibility of a 7-day incubation period for such studies. Using mean values of all P treatments of a 7-day incubation (76 soil P test values), the relationship was further improved (r = 0.92", P = 0.01) by a workable predictive equation of labile-P (Pa) from Olsen-P (OP): Pli 7.936 + 1.385 OP
A. Rashid, T. Hussain , A. Razzaq. (2001) Relationships between labile phosphorus and olsen phosphorus test values of alkaline soils, The Journal Soil & Environment , Volume 20, Issue 4.
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