Utilisation of Zinc from Zinc Fertiliser Bands: Effect of Concentrations of Zinc in Zinc Chloride and Zinc-Edta Fertiliser Bands on Root Growth and Zinc Uptake by Wheat

ABSTRACT

Factors affecting the extent of utilisation of zinc from zinc fertiliser bands include the extent of solubility and movement of zinc from the fertiliser band, the extent of root to zinc fertiliser contact as well as the concentration and extent root growth in the fertiliser band. Growth chamber and incubation studies were conducted to compare the extent of root growth and zinc uptake by wheat (Triticum aestivum var Columbus) from Zinc chloride (ZnCl₂) and Zn-EDTA fertiliser bands when applied to a non-calcareous soil of pH 7.0 and low in DTPA-extractable Zn. The Zn fertilisers were uniformly mixed with 200 g of soil contained in acrylic cylinders. Concentrations and forms of water-soluble Zn in the fertiliser bands were determined from the incubation studies. Concentrations of Zn in the Zn-EDTA fertiliser bands were much greater than concentrations of Zn in the ZnCl₂ bands. Whereas root growth was stimulated by low rates of ZnCl₂, high rates of Zn (>0.8 mg Zn/cm³) resulted in a decrease in the amount as well as quality of roots recovered from the fertiliser band. Zn-EDTA reduced root growth into the fertiliser band for most of the rates of Zn applied. The results obtained showed that root growth into the fertiliser bands was closely related to the concentration of Zn in soil solution. Concentrations of Zn in the plant shots increased with increase in the amount of roots in the fertiliser bands as well as the concentration of Zn in soil solution.