S Safarzadeh ShirazI - PhD. Student, Prof., Prof., and Assist. Prof, respectively, College of agriculture, Shiraz
A.M Ronaghi
N Karimian
J Yasrebi

The effect incubation time and application of Cd-emiched sewage sludge on Cd availability in soil and bioavailability to rice (0 1yza Sativa L.) were investigated. Soil was treated with 20 g kg -1 of sewage sludge and it had been emiched with different amounts of CdS04 to obtain Cd concentrations ranging from 10 to 90 mg Cd kg - 1 . Soil was extracted with DTP A after 1 and 120 days. Availability of Cd in soil and Cd concentration in rice shoots at two incubation times, increased with increasing levels of Cd in soil. Incubation time had a significant effect on Cd concentration in rice it was significantly higher at 120 days of incubation than at first day of incubation probably due to degradation of organic matter and release of the Cd in soil. Shoot Cd concentrations con elated with DTP A -extractable Cd in the soil. Therefore, DTP A -extractableCd could be successful in predicting Cd bioavailability and toxicity in rice plant

DTPA-extractable Cd; rice; Cd concentration; Cd-emiched sewage sludge