Zinc in wheat grain as affected by nitrogen fertilization and available soil zinc

Greenhouse and field experiments were conducted to determine the influence of nitrogen (N) fertilization and DTPA-extractable soil zinc (Zn) on Zn concentration in wheat (Triticum aestivum L., cv. Pioneer 2375) grain. Application of zinc sulfate (ZnSO4) in the range of 0 to 8 mg Zn kg(-1) increased linearly DTPA-extractable Zn in an incubated calcareous soil from 0.3 to 5.0 mg kg(-1). Application of these rates of ZnSO4 to the same soil under greenhouse conditions increased Zn concentration of wheat grain from 26 to 101 mg kg(-1). The influence of 134 kg urea-N ha(-1) on Zn concentration in wheat grain at eight field sites, with DTPA-extractable soil Zn levels ranging from 0.3 to 4.9 mg kg(-1), was studied. Nitrogen fertilizer increased wheat-grain yields in four of the eight experiments but had little effect on grain-Zn concentration Grain-Zn concentration ranged from 31 to 45 mg kg(-1) in N-fertilized plots at the various sites and was related (r=0.74*) to DTPA-extractable soil Zn.