Abstract:

To study the effects of tillage methods (plow tillage, rotary tillage, no-tillage and straw retention) on heavy metal cadmium accumulation in rice-wheat rotation system in Chengdu Plain, and to explore the optimal agricultural production pattern in Cd contaminated fields, a two-year field experiment was performed on the Cd contaminated fields. The experiment was carried out with different tillage methods, including plow tillage with straw retention, plow tillage with straw removed, rotary tillage with straw retention, rotary tillage with straw removed, no-tillage with straw retention and no-tillage with straw removed, to analyze their effects on crop yield and Cd content in straw and soil. The results showed that plow tillage treatment could significantly reduce the heavy metal Cd concentration in wheat and rice grain compared with the rotary tillage and no-tillage. Under the same tillage method, straw retention had no great impact on the wheat and rice grain Cd concentration. Compared with the rotary tillage and no-tillage, the total and available Cd content of topsoil and the Cd content in straw under plow tillage were significantly lower. Therefore, to ensure the crop yield and reduce the Cd content in agricultural products, plow tillage is one of the effective technical patterns for the safe production of the wheat-rice rotation system in Cd contaminated fields in Chengdu Plain.

Key words: tillage method, straw retention, cadmium pollution, rotation