Mobility and extractability of zinc in soil columns amended with micronutrient formulations

The behaviour of zinc (Zn) was studied by adding a slow‐release fertilizer (Micromax) which contains zinc sulfate (ZnSO4) to soil columns of two types of soil of distinct characteristics, but both soils with critical levels of Zn available to plants (extractable with DTPA). By sequential extraction, the residual amount of Zn in the soils was found to be the major fraction which explained the deficiency of this micronutrient in the two soils. After three months in the soil columns subjected to systematic irrigation, the added Zn evolved throughout the soil columns, modifying the percentage distribution of Zn at the various depths. The most labile fraction, and thus the most available to plants was increased. In the soil with the highest pH, and active calcium carbonate (CaCO3) and clay contents, Zn migrated less, moving only a short distance; while in the acid soil, Zn evolved throughout the whole column. The DTPA‐extractable Zn content increased considerably in the zone where the fertilizer was applied, remaining at an adequate level of availability to plants until the end of the test. A high correlation between the Zn extractable with DTPA and that fraction in the organic complexes was found (r = 0.86, P = 0.001).