The kinetics and amount of phosphorus (P) release from five Italian soils w
ith and without added P, were assessed by a successive soil P extraction pr
ocedure using iron (Fe) oxide-impregnated paper strips to characterize the
residual effectiveness of added P. Following P application to soils (0, 25,
50, and 100 mg kg(-1) soil), P removed in the first extraction (strip P),
P released in ten extractions (total P), and soil P sorption saturation (P-
saturat) increased for all soils. The rate of P release decreased with succ
essive strip extraction of soil [Strip P=a*(extraction number)(b); R-2 of 0
.89-0.99], with the exponent b decreasing as the saturation of soil P sorpt
ion capacity increased. Both initial P and total P released to strips incre
ased with soil P saturation.