1Central Potato Research Institute, Shimla-171 001, (H.P.).
2National Bank for Agricultural and Rural Development, Lucknow, (U.P.).
Direct and residual effect of P and K applied to potato was studied on 3 successive crops in 3 different soils from Shimla district Significant response to P was observed in Kufri soil while residual effect of P was not significant in all soils. P uptake significantly increased but its residual effect was significant in Shimla soil. There was steep fall in available P content in Shimla soil in absence of P. Fractionation studies carried out on soils showed that applied P finds its way into Al-P followed by Fe-P and Ca-P.
Response to K application was not significant but significant response to residual K was observed in Shimla and Kufri soils. K applicalion increased K uptake in all the three soils and significant responses were observed during summer. In absence of K, 3 potato crops removed 58, 64 and 77% of the available K from Shimla, Kufri and Galoo soils, respectively. With K application, all soils were enriched in available K by 23 to 25%. There was Continuous fall in water soluble K after each crop. Total K content in Shimla and Galoo soils showed gradual decrease.
