Evaluation of Soil Tests for Zinc in Central Alluvial Soils of Uttar Pradesh

Suitability of the six extractants viz., 0.1 N HCl, 1N NH₄OAc (pH 4.6), IN NH₄Ac (pH 7.0), 2N MgCl₂, N NH₄Ac (pH 7.0) + dithizone, and EDTA for determining avail. Zn in alluvial soils of Uttar Pradesh was evaluated. The soil test values for avail. Zn were correlated with the per cent yield and the concentration and uptake of Zn in grain and straw. The highest correlations between soil test values and various variables were observed when NH₄OAc + dithizone was employed which thus seems to be the best extractant. The critical limit of dithizone extractable Zn was found to be between 0.45 and 0.80 ppm