A field experiment was conducted in typical cadmium polluted farmland in Quzhou,Zhejiang,with Chunyou 84 and Zhongzheyou 8 as experimental materials,to study the effects of organic fertilizer and soil conditioner on pH and available state of heavy metal elements(Cd,Fe,Mn,Zn,etc.)in soil,and accumulation of heavy metal elements in rice plants(straw,grains),and their mechanism of reducing grain Cd accumulation.The results showed that single application of organic fertilizer(1.5 t/hm2)had no significant effect on the effective state of heavy metal elements in soil and the content of heavy metal elements in rice straw and grains.However,under the combined application of organic fertilizer(1.5 t/hm2)and soil conditioner(2.7 t/hm2),the soil pH increased,but the available state of heavy metals in the soil and the content of heavy metals in rice plants showed a downward trend.The available Cd content in soil decreased by 16.41%(DTPA extraction)and 48.96%(CaCl2 extraction),while the Cd content in rice straw and grains decreased by 40.04%and 48.22%,respectively.Stepwise regression and path analysis showed that the Cd content in rice straw and Cd availability in soil were significantly correlated with Cd content in grains.It can be seen that the application of soil conditioners reduces the available content of heavy metal elements in soil by increasing soil pH,with a particularly significant decrease in available Cd content,thereby regulating the accumulation of Cd in rice straw and grains.Therefore,it indicates that the tested soil conditioner can be promoted and applied in acidic soil areas,with the effect of increasing the pH of acidic soil and reducing the enrichment of Cd in rice.
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