Effect of Soil Properties on Boron Adsorption and Release in Arid and Semi-Arid Benchmark Soils

The adsorption isotherms indicated that the adsorption of boron (B) increased with its increasing concentration in the equilibrium solution. The Langmuir adsorption isotherm was curvilinear and it was significant when the curves were resolved into two linear parts. The maximum value of adsorption maxima (b1) was observed to be 7.968 mg B kg-1 in Garhi baghi soil and the bonding energy (k) constant was maximum at 0.509 L mg-1 in Jodhpur ramana soil. The Langmuir isotherm best explains the adsorption phenomenon at low concentrations of the adsorbent, which of course was different for different soils. There was significant correlation between b1 and clay (r = 0.905**), organic matter contents (r = 0.734*), and cation exchange capacity (CEC; r = 0.995**) of soils. A linear relationship was observed in all the soils at all concentration ranges between 0 and 100 mg B L-1, indicating that boron adsorption data conform to the Freundlich equation. Soils that have a higher affinity for boron adsorption, like Garhi baghi, tended to desorb less amount of boron, that is, 43.54%, whereas Ballowal saunkhari desorbed 48.00%, Jodhpur ramana 48.42%, and Naura soil 58.88% of the adsorbed boron. Boron desorption by these soils is positively and significantly correlated with the sand content (r = 0.714**) and negatively with clay content (r = -0.502*) and CEC (r = -0.623**). The maximum value of 37.59 mg kg-1 for desorption maxima (Dm) was observed in Garhi baghi soil and also a constant related to B mobility (Kd) was found to be maximum in Garhi baghi (0.222 L kg-1) soil Note: *P0.05; **P0.01.