CUMULATIVE AND RESIDUAL EFFECTS OF ZINC SULFATE ON GRAIN YIELD,ZINC, IRON,AND COPPER CONCENTRATION IN CORN AND WHEAT

Re-application of zinc (Zn) sulfate for corn (Zea mays L.) production in rotation of wheat-corn has varied effects on yield of crops grown in Zn deficient soils. Therefore, this study was done as split plots in a complete randomized block design (CRBD) where the main plots were control with and without Zn application in wheat (Triticum aestivum L.) production. Sub-plots were of control, without Zn fertilizer, base application of 75 kg per hectare (kg Zn ha^?1), 25% and 50% less than base application and as foliar spray in combination with the 4 soil Zn treatments for corn production. Effect of previous Zn application on grain Zn concentration of corn was significant (P < 0.01). Zinc concentrations in treatments of without previous Zn (nil Zn) application and with Zn application were 28.1 and 31.8 mg kg^?1, respectively. Soil application of 75 kg ha^?1 and foliar application of Zn sulfate gave the highest yield (8853 kg ha^?1) showed an increase of 25 percent in compared with nil-Zn. Although re-application of Zn has small effect on yield, but resulted in was the highest grain concentration.