Mobility and leachability of zinc in two soils treated with six organic zinc complexes

A study of soil columns was conducted to evaluate Zn movement potential in two reconstructed soil profiles. Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignos ulfonate, Zn-polyflavonoid, and Zn-heptagluconate were applied in the upper zone of the column. The different physicochemical properties of the two so ils and the micronutrient source may influence Zn leaching, the distributio n of Zn among soil fractions, and the Zn available to the plant in the dept h of the layers. In Aquic Haploxeralf soil, the application of six fertiliz ers produced little migration and very small leaching of Zn in the soil pro files. In Calcic Haploxeralf soil, Zn-EDTA migrated and was distributed thr oughout the soil columns. This Zn chelate produces a loss of Zn by leaching , which was 36% of the added Zn. In the latter soil, Zn leached very little with the other five fertilizer treatments. The same as for these organic Z n complexes, the retention of added Zn indicated the potential of metal acc umulation in the Ap horizons of the two soil profiles. A large portion of a pplied Zn was available to plants [diethylenetriaminepentaacetic acid (DTPA ) and Mehlich-3 extractable Zn] in the depths reached by the different comm ercial formulations. The relationship between the two methods was highly si gnificant (Mehlich-3-Zn = 1.25 + 1.13 DTPA-Zn, R-2 = 99.19%). When Zn was a dded as Zn-EDTA, the amounts of the most labile fractions (water-soluble pl us exchangeable and organically complexed Zn) increased throughout the enti re profile column in comparison with the control columns, although in the B t horizon of the Aquic Haploxeralf soil they increased only slightly.