Correction of zinc deficiency in maize on the Darling Downs, Queensland

Abstract

Zinc applied as a 0·5% zinc sulphate spray completely corrected symptoms of zinc deficiency. Copper, boron, magnesium, potassium and phosphorus applied as foliar sprays did not correct symptoms. Concentration of solution (0·5, l·0 and 1·5 %) and number of applications (1 and 2) did not affect plant response significantly. There is evidence in one trial, and a trend in the other, to indicate that spraying at 7 weeks from emergence is too late for zinc sprays to increase yield, and that the optimum spraying time appears to be at about 5 weeks after emergence. Yield increases from zinc foliar sprays ranged from 24 to 76% over control.