H. Vandenhove et al., Phosphate sorption by Sri Lankan soils used for rice production: Relation between Tempkin sorption coefficients and soil and plant parameters, TROP AGR, 75(3), 1998, pp. 355-362
The common soil-P tests are unable to distinguish between P-deficient and P
-sufficient Sri Lankan soils used for rice cultivation, therefore adsorptio
n experiments were performed to determine whether sorption parameters as ob
tained from the Tempkin equation are more appropriate. Phosphate sorption i
s mainly governed by amorphous Fe- and Al-hydroxides and (or) oxides, clay
content and its mineralogy, soil carbon content, and the amount of gibbsite
. Removal of Dart of the available P with the Pi-P test prior to the sorpti
on experiment, affected the so-called P sorption maximum, a but not the soi
l buffering capacity, b. Soil extraction with oxalate reduced both sorption
parameters (a and b) significantly. A negative correlation was obtained be
tween Tempkin sorption coefficients the per cent shoot P and yield (only fo
r buffering capacity). Using the P-sorption data it can be explained why so
me fields responded to P and some did not.