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

A field experiment was 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 residual effect of combined application of Zn₅₀ and K₈₀ resulted 32.1 per cent increased in pod yield of groundnut. Individual application of each levels of Zn,Fe and K had non significant residual effects on pod and haulm yield of groundnut in pooled results. Simultaneously, individual application of Zn, Fe and K increased their respective concentration and uptake by pod and haulm of groundnut.