Study On Remediation Mode Of Cadmium Pollution In Farmland By Intercropping With Sedum Plumbizincicola And Sorghum Under Enhanced Measures

Heavy metal pollution in agricultural fields has become one of the main reasons threatening the safe production of agriculture,and the development of reasonable measures for the treatment of heavy metal pollution in agricultural soils has become an urgent task to ensure the safe production of agricultural products,compared with conventional physicochemical restoration methods,the phytoremediation method has the advantages of low cost,easy operation,and relatively friendly to the soil environment,but due to its long restoration time,low restoration efficiency,and taking up agricultural production time,etc.However,the application of phytoremediation is limited due to its long restoration time,low restoration efficiency,and time consuming agricultural production.Therefore,this paper takes cadmium-polluted farmland as the research object,uses field experiments,and carries out the study of cadmium pollution mode of farmland remediation by super-accumulated plant Sedum plumbizincicola and sorghum intercropping under enhanced measures,in order to provide a theoretical basis for the research on cadmium-polluted areas in farmland.The main findings are as follows:(1)Under different application amount activator treatment,all treatments had a significant p H reduction effect in the first 14 days,and under the condition of single application of the activator,the p H reduction was the most significant on the 14th day after Oa3 treatment.The p H decreased by 2.08 units,and the p H decreased most significantly on the 14th day after Ha1-Oa treatment,reducing by 1.60 units,the effective cadmium content in soil increased significantly with time,and the Oa2 treatment increased the most significantly on the 28th day after the activator application alone,compared with the same period of CK treatment,the increase was 0.21mg/kg,and under the combined application of potassium humate and low molecular weight organic acid,the most significant increase was achieved on the 28th day after Ha3-Oa treatment.Compared with the same period,CK treatment increased by 0.26mg/kg.The application of activator promoted the transformation of cadmium in soil residue to other three forms with time,and the proportion of cadmium in acid extraction increased the most,the lifting effect of oxalic acid was concentrated in the first 14 days,the lifting effect of tartaric acid was concentrated in the first 21 days,and the combined application of potassium humate and low molecular weight organic acid was concentrated in the first 14 days.(2)Under different intercropping mode processing,Intercropping of sorghum and associated Sedum plumbizincicola requires reducing the density of sorghum planting to achieve simultaneous production and restoration,After the influence of planting density of M3 and M5 sorghum yields decreased by 30%and 27%,respectively,the yield of Sedum plumbizincicola was 4891.68 kg/hm~2and 5846.93 kg/hm~2,respectively,which met the yield requirements of remediation plants;The intercropping between sorghum and Sedum plumbizincicola significantly reduced soil p H,significantly increased the content of cadmium in the soil available state,and effectively promoted the conversion of cadmium in soil residue to cadmium in acid extraction;The intercropping of sorghum and Sedum plumbizincicola inhibited the growth of Sedum plumbizincicola and had no effect on the growth of sorghum,the inhibitory effect of Sedum plumbizincicola is affected by the sorghum spacing on the left and right of the Sedum plumbizincicola strip,and the smaller the spacing,the more significant the inhibition effect;Intercropping significantly increased the cadmium content of stem and leaf of Sedum plumbizincicola and improved the enrichment efficiency of Sedum plumbizincicola,and the accumulation of cadmium per plant of Sedum plumbizincicola was basically the same as that of monocropping when the sorghum strip spacing was≥51 cm in the Sedum plumbizincicola strip.(3)Under the treatment of sorghum and Sedum plumbizincicola under different strengthening measures,the improvement of the restoration effect of the activator on Sedum plumbizincicola was realized by the increase of the biomass of Sedum plumbizincicola,and the activator had no significant effect on the cadmium content of all parts of the Sedum plumbizincicola,among which the HT treatment had the most significant effect,and the production of M3 and M5 mode of Sedum plumbizincicola increased by 21%and 39%,respectively.Both M3 and M5 models achieved the highest cadmium extraction rate under HT treatment,and the repair time was the shortest under their respective strengthening measures,both were 4 years.The M5 mode(Sorghum intercropping with Sedum plumbizincicola 2:4 strip intercropping;The transverse spacing of Sorghum strips is 85cm and transverse distance between the two adjacent rows of Sorghum is 17cm and the longitudinal distance is 34cm,The transverse and longitudinal spacing of Sedum plumbizincicola strip is17cm,The planting density of Sedum plumbizincicola was 230325 plant/hm~2,and the planting density of sorghum was 57581 plant/hm~2)under HT treatment was determined the best repair mode for this experiment,That is,under the intensive treatment of potassium humate 4m L/m~2and tartaric acid 0.3 mol/m~2,sorghum and sedum 2:4 strip intercropping repair mode.