Effect of integrated use of industrial waste and chemical fertilizer onphosphorus uptake and crop yields

Industrial wastes like filter cake (FC), poultry waste (PW) and thebyproduct, di- calcium phosphate (DCP) were integrated with mineralfertilizers, single super phosphate (SSP) or diammonium phosphate (DAP) in2:1 P ratio and evaluated against standard fertilizer DAP, by measuringtheir effect on the efficiency of P-uptake and crop yield. Phosphorus wasapplied at the rate of 75 mg kg-1 to maize and to following wheat andassessed the effect of residual P by growing rice in the same pots. Maizewas harvested at vegetative stage while wheat and rice at maturity.Application of P from the mineral source only or integrated use ofindustrial wastes and mineral fertilizers significantly increased the drymatter yield (DMY) of 42 days old maize plants over control. Integrated useof FC, PW and SSP in 1:1:1 P ratio produced maximum DMY. Combinedapplication of PW and DAP in 2:1 P ratio produced 96 percent, whereasapplication of mineral fertilizer (DAP only) produced 73 percent of themaximum yield. Phosphorus uptake and P fertilizer efficiency (PFE) bymaize was maximum where P was applied through PW plus DAP combinationwhile application of DAP resulted in only 68 percent of the maximumuptake. Integrated use of PW plus DAP in 2:1 P ratio produced maximumgrain yield of wheat grown after maize. Phosphorus applied through othercombinations such as PW plus SSP, DCP+DAP or FC plus PW plus DAP,produced 99, 99 and 97 percent of the maximum yield while application ofDAP alone produced 85 percent of maximum. Similarly, P uptake and PFEwere 28 and 33 percent higher compared to DAP alone. Assessment of theresidual P effect on rice showed that integrated use of waste products andchemical fertilizer produced 22 to 69 percent higher grain yield comparedto DAP alone. It may be concluded from the study that integrated use ofPW and DAP in 2:1 P ratio was the best combination which may prove moreproductive and cost effective.