A pot experiment was conducted to study the effects of different application
sources i.e. Zn S04 7H20, Zn CI2 and Zn-EDTA and rates nemly, 1.5, 3.0, 6.0 and
12.0 mg/kg soil of Zn on grain and straw yield of rice (Giza 178), rice grain Zn content
and distribution of zinc fractions and their transformation in rice soils during the
growing season. The obtained results showed that the different sources of Zn increased the
yield of grain and straw as compared with the control. But, ZnS04.7HzO had slightly
effective less than ZnEDTA and ZClz sources. Also, the yield was affected by the
different rates of Zn sources. Data indicated that the highest increase (85 %) of grain
yield was obtained at 6 mg Zn rate, while the highest increase (130 %) of straw yield
was obtained at 12 mg Zn. The macronutrients N, P and K uptake by grain and straw and its Zn
concentrations increased by the studied Zn sources additions. The highest increases in straw Zn concentration were obtained with ZnEDTA
and ZnCl_z sources. But, the highest increases in grain Zn concentrations were
obtained with ZnS04.7H20 sources. Generally, the 6 mg Zn.kg-' soil rate was the best
treatment. The Zn contents of soil through the growing season were chemically
fractionated into: water soluble and exchangeable (Zn-CA), weakly bound to inorganic
sites (Zn-ACC), organically bound (Zn-pYR), occluded as free oxide material (Zn-OX),
and residual (Zn-Res) mainly in the mineral structure. These fractions constituted
ranged form, 0.2 to 7.4, 2.9 to 17.5, 1.0 to 20.0, 3.9 to 18.3 and 54.2 to 85.9 % of the
total soil Zn respectively which ranged from 95.5 to 333.8 rnq.kq", Therefore, it could be concluded that the application of Zn EDTA source at 6
mg Zn. Kg-' soil rate was sufficient to produce a high rice yield and increase grain Zn-
uptake.