Magnesium Deficiency and Corn Yield on Two Acid Indiana Soils

Abstract

Field experiments were conducted on two acid, sandy loam soils of northern Indiana (Newton, pH 4.7 and Tracy, pH 4.8) to determine the influence of magnesium, calcitic lime, and potash on yields, magnesium deficiency symptoms, and leaf composition of corn. Treatments included factorial combinations of 100 and 500 pounds K2O, 0 and 72 pounds Mg (as MgSO4 · 7 H2O), and 0 and 6 tons of calcitic bag lime per acre. On the Newton soil both potash treatments induced widespread magnesium deficiency symptoms. Their identity was confirmed by low magnesium and high potassium contents of leaves. The occurrence of magnesium deficiency symptoms was not accompanied by a reduction in corn yield. Magnesium additions essentially prevented development of the symptoms, significantly increased the percentage of magnesium, and decreased the percentage of potassium in leaves, but did not affect yields. On the Newton soil calcitic lime produced significant yield increases, but did not significantly affect K-induced magnesium deficiency symptoms nor percentage of magnesium in the leaves. On the Tracy soil only a few plants showed magnesium deficiencies, and none of the potash, lime, or magnesium treatments significantly affected yields. The evidence indicates that yield-limiting magnesium deficiency symptoms with corn are not likely to result from the use of calcitic lime and potash in amounts presently recommended on these soils.