The Growth Of Wheat And Absorption To Cadmium With Different Proportion Of Composted Sludge Application To Loess

In view of the loess- wheat in arid areas system, formulated pot experiment and research on the effect to plant growth by different cadmium pollution levels and different proportions(0%, 0.5%, 1.5%, 3%, 6%) of composted sludge application to Loess. This research helped to understand the interaction between soil heavy metal pollution and the accumulation of heavy metals in plants. The main research results were as follows:1. The pH of the soil with sludge was less than that of loess. Organic matter content in the soil with compost was more than that in loess. Cd content was improved after using compost. The 0.5~6% content of compost may promote wheat growth and more was better. The height, the dry weight and the quantity of seed was improved by compost. The promotion of different parts of wheat showed root> stem> grain.2. When the Cd stress was between 0~ 2.4 mg·kg-1, Cd content in root, leaf and seed decrease as compost addition into loess. But when the Cd stress was between 9~ 12 mg·kg-1, the situation was just the opposite.3. When the Cd stress was below 4.4 mg·kg-1, exchangeable Cd content decreased as compost addition into loess. But when the Cd stress exceeded 9 mg·kg-1, the compost will led to exchangeable Cd increasing. Carbonate-bonded Cd did not change obviously by compost application. Fe-Mn oxides bound Cd content decreased as compost ratio increasing, except when the Cd stress was 0.8 mg·kg-1. Organic Cd and residual Cd content decreased than that in loess after compost application.4. The exchangeable and carbonate-bonded Cd made the most contribution to the content of cadmium in all parts of wheat and they were the bio-available species. When the Cd stress was between 0~4.4 mg·kg-1, bioavailability of Cd became weaker as compost addition into loess. And when the Cd stress was between 9~ 12 mg·kg-1, bioavailability of Cd improved as compost addition. The correlational analyses showed that Cd content of all parts of wheat was positively correlated with bioavailable species of Cd and negatively correlated with potential available species and unavailable species.