A greenhouse experiment was carried out to evaluate the effect of the Ca/Mg ratio in the cation exchange capacity on common bean growth. Samples of a typic ferric aluminum Red Latosol (LVat) and a psamitic dystrophic Red Latosol (LVdp), both Haplortox (U.S. Soil Taxonomy) in pots containing 3.5 dm³ of soil were treated with Ca:Mg ratios of 1/2, 1, 2, 4, 6 and 8. The experiment was arranged in a completely randomized block design with six replications. Three replications were harvested at the flowering stage and the rest kept until the grain harvest. Dry matter weight, obtained at the flowering stage, was similar in both soils; the grain yield in the LVat, however, was 40 % higher than the one obtained in the LVdp. Nevertheless, these variables were not significantly affected by the Ca/Mg ratios. Ca and Mg contents in the tissue and their ratios during flowering were closely related to exchangeable soil Ca and Mg contents and Ca/Mg ratios. Results showed that in soils with suitable levels of exchangeable Ca and Mg, the Ca/Mg ratio is of secondary importance for the development and grain yield of common bean.
Phaseolus vulgaris; Ca/Mg ratio; base saturation; liming
