Mobility and distribution of zinc forms in columns of an acid, a neutral, and a calcareous soil treated with three organic zinc complexes under laboratory conditions

Abstract

Three liquid zinc (Zn) fertilisers were mixed with the upper 1.5 cm of columns representing 3 different soil profiles: Aquic Haploxeralf, of an acid nature and with hydromorphic problems; Calcic Haploxeralf, of a neutral nature; and Typic Xerorthents, of a calcareous nature. They were periodically irrigated for 60 days. Most of the applied Zn remained in the top of the soil when it was added as Zn-lignosulfonate plus EDTA or Zn-2-hydroxy-1,2,3-propanotricarboxilate. When Zn-EDTA plus fulvic and humic acid fertiliser was applied, Zn migrated and distributed throughout the soil resulting in losses of Zn by leaching of 2.29% in acidic soil, 27.36% in neutral soil, and 10.5% in calcareous soil of the Zn applied. The 3 fertilisers produce sufficient concentrations of the bioavailable Zn forms in the A_p horizons (DTPA and Mehlich-3 extractable Zn) for the cultivation of different plants. In the calcareous soil, which contained free CaCO₃, the amount of Zn extracted by Mehlich-3 was higher than in soils with no free CaCO₃. Distribution of Zn in the soil was studied at the beginning and end of the experiment by means of one sequential fractionation and showed that added Zn remained in more labile fractions for uptake by plants in the acid and neutral soils when compared with the control. When Zn was added to calcareous soil, no amount of Zn was detected in the water-soluble plus exchangeable fraction at the end of experiment for any Zn fertiliser source.