Direct and Residual Effect of Zn, Fe And K on Yield and their Uptake by Wheat Groundnut Crop Sequence in Medium Black Soils

Results of field experiment carried out in medium black calcareous soils (Typic ustocrepts) on fixed plots during kharif season of 2005 to 2007 at Wheat Research Station, Junagadh Agricultural University, Junagadh with eighteen treatment combinations comprising of three levels of Zn (Zn₀ - 0, Zn₂₅-25 and Zn₅₀ -50 kg ZnSO₄ ha^-1), two levels of Fe (Fe₀ - 0 and Fe₅₀ - 50 kg FeSO₄ ha^-1) and three levels of Potassium (K₀ - 0, K₄₀ -40 and K₈₀ -80 kg K_2O ha^-1) in a randomized block design with four replications. The combined application of Zn₅₀ and K₈₀ resulted 27 per cent increase in grain yield. Simultaneously, Fe₅₀ also increased the yield significantly. Individual application of Zn or K increased their uptake by crop and their availabilities.