Effect of continuous application of Zn, Cu and Fe on yield and availability of nutrients in a cropping system.

Effect of continuous application of Zn, Cu and Fe to a cropping system on yield and availability of both major and micronutrients was studied in a red loamy soil. Marginal increase in yield of maize grain for Cu, substantial increase in both kernel and haulm yield of groundnut for the individual application of all the three micronutrients and also for Zn and Fe in the third crop of sorghum were observed. Among the major nutrients, only availability of P was reduced at higher levels of Zn and Cu, particularly in the first two crops and Fe in the third crop. Substantial increase in available Zn and Cu was observed at added levels of Zn and Cu. However, availability of Fe was not increased due to its application to soil.