Nutrient Balance Involving Phosphorus, Iron, and Zinc
1965
Watanabe, F. S. | Lindsay, W. L. | Olsen, S. R.
Corn (Zea mays L.) and pinto beans (Phaseolus vulgaris) were used as test crops to study the interactions between P, Fe, and Zn in a calcareous solution culture. The addition of Zn to the intermediate Fe level accentuated Fe deficiency symptoms and depressed the yield of corn. This adverse effect on yield was not related to the Fe concentration in the plant but was associated with a decreased Fe/Zn ratio. In this study the antagonistic effect of Zn on Fe was manifested by reduced yields as the ratio of Fe/Zn in the tissue decreased below 1.5. Addition of Fe corrected this adverse effect on yield. By increasing the P at the intermediate Fe level the yield first increased; then P-induced Fe deficiency symptoms appeared, accompanied by a depression in yield. This phenomenon was not associated with change in Fe concentration but was related to high P concentration in the plant tissue, which resulted in a P/Fe ratio > 60. The addition of Fe did not change the Fe concentration but corrected the depression in yield. A P/Zn concentration ratio > 300 resulted in a slight depression in yield in the presence of an adequate supply of Fe. The depression in yield associated with the antagonistic effect of Zn on Fe and P on Fe and Zn, although manifested on corn, was not found with pinto bean at the concentration levels studied.
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