Direct and residual effect of Hazara rock phosphate (HRP) on wheat and succeeding maize in alkaline calcareous soils

The potential of hazara rock phosphate (hrp) containing 18% acid soluble p2o5 as cheaper substitute for costly commercial fertilizer for crop production,was evaluated. field experiments were conducted on silty clay loam,calcareous (16% caco3),high ph (8.6) soil where 0,250,500,1000 and 1500 kg hrp ha-1 was added to wheat (triticum aestivum l.),cv “serin” with three replications in rcb arrangement. recommended doses of n and k were applied to all plots. maize (zea mays l.) cv “babar” was grown as a succeeding crop for evaluating the residual effect of hrp as a source of p. addition of hrp produced significant increase in wheat grain and biomass yield over control. hrp demonstrated a significant residual effect on grain and biomass yield over control. similar increases were registered in the number of grains,grains spike-1 of wheat and cobs weight and grain weight cob-1 of maize. the variations induced by levels of hrp were mostly similar while the residual levels showed better results for higher doses compared to lower for maize yield and yield components. the soil analysis performed for the growth stages revealed significant water soluble p concentrations with hrp treatments over control suggesting sustained supply of p into the soil solution for crop growth and development. the total p uptake by both wheat and maize closely followed the pattern of wsp,which corroborated the yield data. it was concluded that hrp offer promise as alternate source of p,however,to ensure optimum crop production on high ph calcareous soil,some acidification after careful standardization will be advisable. © 2014,pakistan botanical society. all rights reserved.