effects of sewage sludge application and leaching on soil chemical properties, yield and quality of barley

sewage sludge can be utilized as one of the best and cheapest organic fertilizer in agriculture due to its organic and plant nutrient contents. however, the presence of potentially toxic heavy metals in some sludges can restrict its use in agricultural lands. a greenhouse study was conducted in the college of agriculture, ferdowsi university of mashhad, to investigate the effects of leaching and sewage sludge application on soil properties, yield and quality of barley. the experiment was carried out using a factorial arrangement with a completely randomized design with three replicates. sewage sludge was applied at five levels of 0, 50, 100, 200 or 400 t ha-1 while leaching was performed at two levels of 0 and 10%. at the end of growing season, the soil and plant characteristics were assessed. results showed that increase in sewage sludge application caused a significant (r0.05) increase in all the above mentioned soil characteristics except for the ph which showed a significant (r0.05) decrease. in the case of plant, sign of chlorosis was observed on barley leaves in treatments of 200 and 400 t ha-1 sewage sludge. moreover, a significant (r0.05) increase in the concentration of pb and cd in leaves and stem of barley was indicated due to the increase in sludge application rate. however, the effect of sludge application on the 100 seed weight and plant aerials dry weight was not significant (r<0.05). the effect of leaching factor on soil characteristics was not significant (r<0.05) except on concentrations of mg and ca in soil solution. leaching factor increased plant aerial dry weight significantly (r0.05), but had no effect on the 100 seed weight and concentrations of pb and cd. the interaction effects of sludge application rates and leaching levels were not significant.