Impact of acid soil improvement on form transformation of cadmium in soils and cadmium content in Sauropus androgynus(L.)Merr.

ObjectiveCadmium(Cd) is a toxic heavy metal element and a control index of quality and safety for ag-ricultural products. The effects of acid soil improvement fertilizer on soil Cd form transformation and Cd content in Sauro-pus androgynus(L.)Merr. were studied to provide scientific basis for cultivation of high quality S. androgynus with low Cd.MethodThe liquid acidic soil improvement fertilizer was used to make meliorative treatment on the soil in S. an-drogynus planting test area,then the content of Cd in ion morphology(Cd2+)in S. androgynus in the experimental plot and control plot were monitored regularly during the experiment process by atomic absorption technique,and the change rule was also analyzed.ResultAfter the treatment of liquid acidic soil improvement fertilizer,the pH value of soil in the experiment plot increased from acidic to weakly acidic,the content of water-soluble state,ion-exchangeable state,car-bonate state,and the binding sate of iron-manganese oxide,the organic binding state and the total available state of the Cd were significantly lower than those of the control plot(P<0.05),while the Cd content of residual state was as three times as that of control. The available state of Cd in the control plot as and experimental plot were 0.066 and 0.023 mg/kg respectively. The Cd content of S. androgynus sample in the experimental plot was extremely significantly lower than that of the control(P<0.01),meeting the limiting value of safety standard for pollution-free vegetables(0.05 mg/kg).Con-clusionThe liquid acidic soil improvement fertilizer not only effectively improves pH value of the soil,but also reduces Cd2+ ironic activity in the soil. Consequently,it can improve the quality of S.androgynus and meet the requirements of pol-lution-free vegetables.