Journal of the Indian Society of Soil Science

Available zinc in 15 soils (Vertisols) from wheat growing areas of Madhya Pradesh was evaluated with five extractants viz. DTPA-CaCl₂, NH₄HCO₃-DTPA, NH₄OAc, EDTA-(NH₄)₂CO₃ and MgCl₂. The amounf of zinc extracted by various chemical extractants was in the order of: NH₄HCO₃-DTPA > EDTA-(NH₄)₂CO₃ > DTPA-CaCl₂> NHpAc = MgCl₂. The most suitable extractant for predicting zinc level for wheat crop was DTPA-CaCl₂ followed by (NH₄)₂CO₃-DTPA. Residual zinc contributed 90.7 per cent to total zinc. Complexed, occluded and residual zinc correlated significantly with Bray's per cent yield, concentration and uptake of zinc by wheat. The critical limits of zinc in soils were 0.6 mg kg⁻¹for DTPA-CaCl₂and 0.7 mg kg⁻¹ for NH₄HCO₃-DTPA extractant.