Micronutrient needs of tropical food crops

The trace element requirements of tropical crops are reviewed with special reference to their role, the differences between crop species, the differences between cultivars, paths of trace element uptake, effects of climate, the importance of crop management and yield levels

The effect of successive crops of wheat on the availability of copper fertilizers to plants

Successive cropping with wheat on an acid sandy loam and a calcareous sand rapidly decreased the availability of applied copper sulfate to wheat plants grown in pots. The amount of copper removed in grain and straw was only approximately 10 per cent of the amount of copper applied. Ammonium oxalate-extractable copper also declined with successive crops. Moreover, the relationship between copper uptake and extractable copper also changed with successive crops. The amount of ammonium oxalate-extractable copper required for maximum growth increased with successive crops from 0.2 to 0.4 8g/g soil on the acid sandy loam and from 0.6 to 0.8 8g/g on the calcareous sand