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Comparison of Adsorption Isotherm Equations to Describe Boron Behavior in Soils Affected by Organic and Mineral Fertilization

Diana, Giampietro, Beni, Claudio, Marconi, Simona
Communications in soil science and plant analysis 2010 v.41 no.9-11 pp. 1112-1128
boron, boron fertilizers, organic fertilizers, mineral fertilizers, nutrient availability, sorption isotherms, adsorption, equations, mathematical models, food processing wastes, winemaking, mycorrhizal fungi, composts, Lactuca sativa, lettuce, vegetable crops, boric acid, chemical concentration, exchangeable sodium, Italy
The effects of different fertilization techniques--mineral [21% nitrogen (N)], organomineral (10% N), mycorrhiza inoculumns, wine-producing residues (three different formulas: distiller's residue, 2.2% N; anaerobic digestate, 2.8% N; and the same plus mycorrhizas inoculum), and compost by farm residues (2.0% N)--on adsorption of boron (B) were investigated. The soils, collected after a triennial lettuce (Lactuca sativa L. cv. 'Bacio') cultivation, were equilibrated using six B concentrations [0, 1, 5, 20, 50, and 100 mg B L-1, as boric acid (H3BO3)]. The B adsorption was studied at two soil mass (m(s)) to solution volume (v(s)) ratios, m(s)/v(s) = 0.5 and 1, and the Langmuir, Eadie-Hofstee, Freundlich, and Temkin adsorption equations were fitted to the B adsorption data. The proportion of adsorbed B was gradually less in the more concentrated solutions, with differences in ms/vs ratio and in treatments: the percentage of B adsorbed was greater for m(s)/v(s) = 0.5 and for distiller's residue and mineral fertilizer. The Freundlich isotherm represented the measured B adsorption data well; at m(s)/v(s) = 0.5, the values of Freundlich adsorption maxima Xm varied from 93.14 to 111.88 mg kg-1 (organomineral fertilizer and distiller's residue, respectively; at m(s)/v(s) = 0.5) and from 32.14 to 40.32 mg kg-1 (mineral fertilizer and control, respectively; at m(s)/v(s) = 1). In our study, generally the B adsorption was greater with mineral fertilizers and distiller's residue, whereas the organomineral fertilizer led to a decrease in B adsorption. The parameters of adsorption isotherms were significantly correlated, at various degrees, with the exchangeable cation sodium. The adsorption isotherms were well explained by the lower soil mass to volume solution ratio in the order Freundlich > Temkin approximately equal to Langmuir > Headie-Hofstee.