The residual and cumulative effects of zinc sulfate on micronutrient concentration of corn (Zea mays L.) rotated with wheat (Triticum aestivum L.)

This research was done for determining the effects of residual and cumulative effects of zinc sulfate on grain of corn (Zea mays L.) rotated with wheat (Triticum aestivum L.). The experiment was a split plot on the basis of randomized complete block design with three replications. Treatments including the main plots including application of 40 kg/ha zinc sulfate and the subplots application of zinc sulfate were tested. Subplots consisted of the soil application of 75 kg/ha as the base treatment، and the 25% and 50% of the base treatment. In addition، the foliar application of zinc sulphate at 5 mg/kg were also devoted to the subplots. Analysis of variance indicated that previous soil application effect on zinc concentration of grain was significant at 1% level. Accordingly، concentration of grain zinc in the treatment of control and previous application of zinc sulfate were 28. 1 and 31. 8 mg/kg، respectively. Duncan،s multiple range test (DMRT) indicated that integrated application of 75 kg/ha and foliar application of zinc sulfate with zinc concentration of 34 mg/kg in grain was the highest statistical group، with 54% increase related to the control. Variability of iron، manganese and copper concentrations indicated decreasing trends with soil and foliar application of zinc sulfate. Soil application resulted in higher decrease of experimental elements concentration than foliar application.