Boron sorption in soils and its extractability by soil tests (Mehlich 3, ammonium acetate and water extraction)
Plant Soil and Environment 55(1): 42-49
The aim of the paper was to contribute to the acquisition of background data for the specification of safe boron levels in soils in relation to diagnostics by multi-nutrient soil tests and to CEC (cation exchange capacity) value of soil, pH and soil organic matter. The research was conducted on 24 soils. Sorption was determined after 97 days from the application of B at the rates of 0, 1, 2.5, 5 mg B/kg in H3BO3. The closest regression of B-sorption was with the CEC value of soil in NH4-acetate and water tests and it increased with the increasing application of B (regression at a rate of 5 ppm B; NH4-acetate: linear R-2 = 0.632, polynomial 2(nd) R-2 = 0.644; water: linear R-2 = 0.644, polynomial 2(nd) R-2 = 0.599). No relationship was found in the Mehlich 3 test. Regressions of B sorption on pH value were substantially lower. The relationship of B sorption with soil organic matter was similar to CEC, but less close. In the NH4-acetate soil test, after the correction of CEC value of soil by pH deviations from the optimum, regression was improved (linear R-2 = 0.821, polynomial 2(nd) R-2 = 0.837).