Effects Of Different Amendments On Ecological Security In Cd Polluted Farmland And Cadmium Uptake By Rice In Soil

In view of increasing number of polluted soil contaminated by heavy metals which made the quality of soil decreased a lot and threat to human health and safety got worse,it is of great practical significance to repair and governance the soil contaminated by Cadmium,in order to ensure the safety of agricultural products and development sustainable agriculture.In order to explore the safety production measures of growing rice on Cadmium soil,In view of this,the effect of different passivators on Cadmium soil was studied,The common passivators were lime,sepiolite,humic acid,biochar,Chelated iron fertilizer and so on,The insitu passivation plot test was conducted with two rice(DY: super hybrid rice deyou 4727 and CY: common hybrid rice chuanyou 6203).To study the effects of passivating agents on the basic properties of soil,the ecological security of Cadmium contaminated farmland and the absorption of cadmium by rice,so as to realize the risk control of heavy metal Cadmium contaminated farmland,achieving the purpose of farmland safe utilization and development sustainable agriculture.The fingdings are as follows:(1)Applying with the passivator has a certain impact on the primary physical and chemical properties of the soil.Compared to the CK treatment,soil pH in DY and CY soils increased by 0.08~20.19 units;CY soil organic matter growth was 5.76% to 41.96%,and the DY soil organic matter ranged from-3.18% to 37.21%.The decrease of alkaline nitrogen in DY and CY soils was 0.25% ~ 27.73% and 2.21% ~ 29.71%,respectively.Apart from T1 treatment,available potassium contents in DY and CY soils increased by 3.62% to 103.9% and 14.48% to 96.47%,respectively.In addition,the available phosphorus of DY and CY soils decreased in the treatments of T2,T3 and T7.(2)Applying with the passivator makes Cd and its morphology changed in soil.Compared to the CK treatment,the total content of Cd in DY and CY soils decreased by 0.09% ~ 5.88% and 0.24% ~ 6.60% respectively in the treatments of T2,T6 and T7.Through observation the 7 passivating treatments,the acid extractable capability of Cd in DY soil decreased by 28.19% to 66.47%,respectively.The study found that Cd in DY soil changed from the weak acid extractable to oxidizable and residue state in treatments of T1,T3,T4 and T5.Applying with sepiolite and lime increased the potential ecological risk of Cd in DY and CY soils by 107.1% and 89.57%,respectively.While under other passivating treatments,the potential ecological risk of heavy metals in soil belongs to slight(RI)or moderate(RAC)level.(3)Applying with the passivator has effect on soil microbe and enzyme.The bacterial abundance of Proteus and Acidobacteria in soil had a relatively high level in the treatments of T2,T3 and T4.The study found that soil total nitrogen and alkaline nitrogen had a positive impact on bacterial abundance;soil organic matter and available potassium are the major factors affecting bacterial diversity.The activities of catalase and urease in DY and CY soils increased in treatments of T3,T4 and T5;the activity of phosphatase was inhibited,which helped to inhibit Cd in grains.(4)Applying with the passivator affects the content of Cd and trace elements in brown rice.Compared to the CK treatment,the content of Cd in brown rice decreased and was below the standard limit of 0.2 mg/kg through observing the 7 passivating treatments.The study found that soil nitrogen,catalase and urease were positively correlated with Cd content in brown rice(P < 0.01).Total nitrogen in soil was positively correlated with Cd in brown rice(P < 0.05).Compared to the CK treatment,Mn content in DY and CY brown rice increased by 4.38% to 27.83% and 18.41% to 33.89%,respectively,with T1-T5 treatment reaching a significant level;Fe content in DY brown rice increased by 1.88% to 36.52%;Cu and Zn content in DY and CY brown rice did not change significantly.(5)Applying with the passivator affects rice yield,and accumulation and transport capacity of Cd in plants.Compared to the CK treatment,rice yield of DY and CY increased by 1.14% ~ 6.85% and 9.23% ~ 17.59% respectively apart from T4 treatment.There was no significant difference in rice yield between treatments(P < 0.05).Compared to the CK treatment,the transfer coefficients of DY rice decreased.The accumulation and transport coefficients of Cd by DY and CY were below 1.