Sewage sludge effect on soil fertility and yield of maize as compared to poultry litter, farmyard manure, and chemical fertilizers
2003
Khan, M.A. | Rahim, M. | Ali, S. (University of Arid Agriculture, Rawalpindi (Pakistan). Dept. of Soil Science and Soil and Water Conservation)
Sewage sludge is a waste product of the sewage treatment plants. Such plants are a few in Pakistan at present, but likely to rise in future because of the importance of treating sewage water, before it is dumped in water bodies. In developed countries, sewage sludge is preferably applied on forest and agricultural land as soil amendment instead of burning it or throwing it in oceans or rivers. The present study was carried out at the research farm of the University of Arid Agriculture, Rawalpindi, during 1998 and 1999, to evaluate the usefulness of sewage sludge of the Islamabad Sewage Treatment Plant, as a soil amendment. Field experiments, under rain- fed conditions, were conducted on maize and the sewage sludge was compared with poultry litter, farmyard manure, and chemical fertilizers. The treatments consisted of. control, NP at the rate of 90-60 kg ha-1, farm yard manure (FYM) at the rate of 20 Mg ha-1 poultry litter (PL) at the rate of 20 Mg ha-1, sewage sludge (SS) at the rate of 20 Mg ha-1, 1/2 FYM +1/2 NP, 1/2 PL + 1/2 NP, and SS + 1/2 NP, of the above given rates of each. Urea and diammonium phosphate were used as sources for N and P, respectively. The results of this study showed that sewage sludge was a better source of organic matter and extractable P as compared to commonly used farmyard manure, however, poultry litter was found superior to sewage sludge in these regards. Due to water stress conditions, which prevailed during the growing season of the crop, the different treatments, except poultry litter, did not improve the maize yield. However, it was observed that combined application of a manure and the fertilizers, at half the rates of each improved efficiency of sewage sludge, farmyard manure as well as the fertilizers. Therefore, the farmers have the option of using less rates of the costly fertilizers when applied in combination with the available organic manure at his farm, and get better crop yield and improve fertility of their soil.
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