Interactions of phosphorus, magnesium and zinc on the yield and nutrient content of maize

Abstract

SUMMARYFive Zn-deficient soils designated A–E (pH 7·3–7·7) and a reference soil F (pH 7·6) were used in a glasshouse study on maize in which five fertilizer treatments: 75 μg P/g alone and together with all combinations of 0 and 5 μg/g of Mg and Zn and with 10 μg Mg + 5 μg Zn/g and a control were applied. The forage yield of soils A–E ranged from 2·5 to 2·9 g when no Zn was applied and from 5·1 to 5·6 g with added Zn, showing that Zn was the major limiting nutrient. Applied Mg significantly increased yield, the main exceptions being soils D and E which had the highest exchangeable Mg.Addition of Mg to a P but not PZn treatment significantly increased P concentration and uptake. For soils B and E, Zn addition significantly depressed P concentration in maize. The P treatment significantly depressed Zn concentration but increased Mg concentration and uptake by maize. Although Mg application either depressed or had no effect on Mg content of maize, it caused a significant increase in Zn concentration and uptake. The correlation coefficient (r) between Zn and Mg in maize was – 0·61 (P < 0·001). Possibly, Mg was replacing Zn in the clay lattice or in its metallo-protein complex within the root.