A comparison of four soil test procedures for determination of available phosphorus in calcareous soils of the mediterranean region

A. E. Matar, S. Garabed, S. Riahi, A. Mazid. (11/11/2008). A comparison of four soil test procedures for determination of available phosphorus in calcareous soils of the mediterranean region. Communications in Soil Science and Plant Analysis, 19 (2), pp. 127-140.

Abstract

Four procedures (desorption by anion resin, Olsen, ammonium oxalate and calcium lactate), to determine the available P in soils, were compared in a greenhouse study. Five rates of P (0, 55, 110, 165 and 220 mg/kg) were applied to 18 calcareous soils from Syria and yield response of perennial ryegrass (Lolium multiflorum L.) to applied P was measured. Dry weight of tops correlated very well with the anion resin‐P or Olsen‐P procedures while lactate P and oxalate P results were poorly correlated. Similarly, total P uptake were significantly correlated with both anion resin P (R2=0.85) and NaHCO3‐P (R2=0.82) and less so for the oxalate P (R2=0.63) and lactate P (R2=0.32) methods. All 4 soil test procedures were effective in classifying soils into responsive and non‐responsive to P. Critical soil P levels were 18.5, 11.5, 9.5 and 7.4 mg/kg for the anion resin, Olsen, lactate and oxalate soil test procedures respectively. The Olsen method is our recommendation for calcareous soils since it is a simple, rapid, and reproducible method that is well correlated with plant response.