The Effect of Sewage Sludge on Productivity of a Crop Rotation of Wheat, Maize and Vetch) and Heavy Metals Accumulation in Soil and Plant in Aleppo Governorate

A set of field experiments were conducted in order to study the effects of sludge application to agricultural soil on the heavy metal accumulation in soil and plant and on availability of certain nutrients for plant together with the productivity of wheat, maize and vetch, The experiment included four treatments i.e., (control; inorganic fertilizer according to Ministry of Agric. and Agra. Reform (MAAR) recommendation; sludge (the amount of sludge containing MAAR recommendation of N without any addition of mineral N; and double the amount of sludge without any addition of mineral N) with four replications at Kamari Research station in Aleppo for the seasons 2004-2005. The applied sludge was described and soil was analyzed prior to cultivation. Upon harvesting, the heavy metals (Cd, Pb, Ni and Cr) were estimated in soil and plant in addition to certain nutrients (Total N, P, macronutrients) and organic matter. Significant build up of some heavy metals in soil and plant was noticed by increasing the addition of sludge as compared to the control. Significant increase in organic matter of soil in sludge-fertilized treatment was noticed as compared to the control. Moreover, a significant increase in soil available P was also noticed by increasing the addition of sludge. No significant difference in total N and macronutrients. There were no significant differences in sludge-fertilized treatments on wheat productivity (2.66 and 2.86 ton ha ) as compared to mineral-fertilized treatment (2.93 ton ha ). Maize 11 improving crop productivity. It is unlikely that a single factor in sludge was responsible for this but is more likely to be due to the mixture of nutrients, micronutrients and organic matter that sludge supplies. The arable crops also grown in rotation in these trials may have also substantial cumulative and residual benefits. The addition of heavy metals to the soil during the trial was very small from a triple application of sludge and had minimal effect on crop and soil concentrations. The nature of the Syrian soils and the relatively low concentrations of heavy metals in Aleppo sludges means that it is unlikely that heavy metals from sludge will pose a significant threat, even in the long-term.