Effects of Zinc Fertilization on Zinc Dynamics in Potentially Zinc-Deficient Calcareous Soil

In China, wheat (Triticum aestivum L.) grown on Zn-deficient calcareous soils oft en fails to meet the dietary needs of local populations. The effectiveness of Zn application to a potentially Zn-deficient calcareous soil was measured using two winter wheat cultivars and five Zn fertilizer rates (0, 7.5, 15, 30, 45 kg Zn ha(-1)). The results showed that Zn fertilizer increased grain Zn concentration in 2008-2009 by 11 to 33%; however, grain Zn concentrations were still insufficient for human dietary requirements. The apparent Zn utilization efficiency was between 0.14 and 0.98%. Within 1 wk of fertilizer Zn application, Zn weakly bound to organic matter (Wbo-Zn) increased by amounts equivalent to 63.4 to 84.0% of the fertilizer Zn application. Carbonate-bound Zn increased by amounts equivalent to 6.5 to 10.3% of the fertilizer Zn. The Wbo-Zn fraction decreased gradually with time, whereas mineral-bound Zn increased. Calculations indicated that 62.0 to 78.1% of the fertilizer Zn was mineral bound aft er 639 d. Diethyltriamine pentaacetic acid extractable Zn concentrations increased by 267 to 529% immediately aft er Zn fertilization but then decreased. In conclusion, available soil Zn concentrations increased quickly aft er Zn fertilizer application to a potentially Zn-deficient calcareous soil; however, the available Zn fractions were soon converted to mineral-bound forms that were unavailable for plant uptake.