Amelioration of zinc toxicity in cotton using lime or mushroom compost

Limited areas of cropland in Georgia have been amended with a high‐Zn flue‐dust material, which is causing Zn toxicities to crops. The objectives of this study were to determine the effects of lime and mushroom compost in reducing Zn uptake by cotton (Gossypium hirsutum L). A pot experiment was carried out using a high‐Zn toxic soil anda low‐Zn non‐toxic soil. There were four lime rates (0, 2.24, 4.48, and 8.96 Mg ha−1) and two compost treatments (67.2 Mg ha−1 compost and the same rate of compost plus 4.48 Mg ha−1 lime). There was a steady decline in plant Zn with increasing lime rates for the low‐Zn soil up to 8.96 Mg ha‐1 (soil pH 7.1). For the high‐Zn soil, the lime did little to increase growth up to 8.96 Mg ha−1 (soil pH 6.3), but the compost and compost plus lime gave normal plants (soil pH 6.9). The DTPA‐extractable Zn responded to lime and compost treatments, but Mehlich‐1 Zn was not responsive to treatments. Liming and compost amendments redistributed Zn from the exchangeable fraction to the Mn o...