SOME FACTORS INFLUENCING THE AVALABILITY OF MAGNESIUM IN SOIL AND THE MAGNESIUM CONTENT OF CERTAIN CROP PLANTS

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Abstract
Mg is widely distributed in numerous minerals, usually in association with such metals as Fe, Co, Ni, and Zn. Soils having a low content of Fe are likely to be relatively low in Mg. The mature leached gray sandy loam soil series, relatively low in colloidal content in regions with relatively high rainfall, are most likely to be deficient in Mg for optimum crop production. Mg is a constituent in chlorophyll and the free energy decrease values in the formation of nutrient compounds indicate that it is probably the strongest cation that could readily enter into direct photosynthetic reaction with some of the stronger anions such as carbonates and phos phates. Since nutrients tend to be selectively absorbed by many plants in the order of the relative strength of their ions, it is interesting to consider some of the common measures of ionic strength. By the use of the standard electrode potentials and ionization potentials of ions in combination with solubility values and the available energy in the sunlight, it is possible to predict the relative availability of nutrient ions in the soil, also the intensity of absorption, occurrence in plants, and the light energy required for their assimilation. There seems to be a correlation between the relative strength of nutrient ions used by plants and the light requirements of plants and the quality or food value of the organic compounds synthesized. Plants requiring strong ions for optimum growth require light of high energy value and synthesize organic compounds which on oxidation or digestion may supply the approx. quanta of energy utilized in the synthesis of the material.
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