The Effect of the Calcium‐Magnesium Ratio on the Solubility and Availability of Plant Nutrients

Abstract

AbstractThe purpose of the present paper is to determine the effect of the Ca‐Mg ratio in solution and in the soil on the solubility and availability of certain plant nutrients. In recent years many papers have been published on the effect of the Ca‐Mg ratio on crop production. Certain papers and unpublished data have indicated that the Ca‐Mg ratio affects the solubility of other plant nutrients, esepecially phosphorus, including some of the minor or trace elements. Nutrient solutions have been made up and mixed with common soil clay kaolin as an adsorbing component. The solubility of B, Mn, Zn, Cu, K, and P were determined. Soil from the Kingman area which is quite low in Mg was obtained for greenhouse studies. Wheat and sorghum were grown and analyzed for the above elements. Plant uptake of the nutrients was plotted against the Ca‐Mg ratio. The results showed: A varying Ca:Mg ratio in Kingman soil produced a difference in the weight and height of the plants grown with a maximum plant growth at a Ca‐Mg mol. ratio of 4‐1. All the nutrient elements studied were affected by a varying Ca:Mg ratio in the soil. The effects observed on the minor elements in wheat and sorghum agree qualitatively with most of the effects observed in nutrient solution studies. No direct correlation was found between the ratio of Ca:Mg in the soil as compared to the ratio in the plants, but a general correlation occurs. An overall maximum uptake of the minor elements seems to be provided for both wheat and sorghum at a Ca:Mg ratio of approximately 4:1. A high magnesium soil favors the uptake of Mn and Zn by sorghum and K, B, and Mn by wheat.