COMPARISON OF MATHEMATICAL MODELS TO DESCRIBE BORON DESORPTION FROM SALT-AFFECTED SOILS

Abstract

Boron desorption as a function of time was measured for four salt-affected soils by extraction with 0.05 M mannitol solution. Four mathematical models (power function, pseudo-first order, Elovich, and parabolic diffusion) were used to describe B release. Comparison of coefficients of determination (r²) and standard errors of estimate (SE) indicated that the power function, pseudo-first order, and Elovich equations adequately describe B release, whereas the parabolic diffusion equation does not. The results further showed that two separate pseudo-first order reactions due to desorption from two independent B retention sites were involved. About 85 to 90% of the total desorbable B could be ascribed to site 1, which is the most rapidly desorbable fraction. The remaining 10 to 15% was from site 2.