Safe Planting Of Peppers In Typical Moderately Cadmium-contaminated Farmland Technical Research In Guiyang

In recent years,a series of crop safety production problems caused by excessive Cd content in food crops due to Cd pollution in farmland soil need to be solved urgently.In order to ensure the safety and green development of the agricultural industry,it is of great practical significance to discuss the safe utilization technology of Cd-contaminated farmland soil.In this study,the typical moderate Cd-contaminated farmland soil（yellow soil）in Guizhou Province was selected as the research object.Select phosphorus-containing substances（bone meal,calcium magnesium phosphate fertilizer,potassium dihydrogen phosphate）,biochar（corn stover biochar,coconut shell biochar,rice husk biochar）and clay minerals（sepiolite,palygorskite,zeolite）3 different types of improved materials.Through the indoor soil culture test,the types of materials with good passivation effect and the appropriate addition amount were screened out,18 common pepper varieties in Guizhou Province were used as the research objects,and the low-accumulation varieties of Cd were screened out through hydroponic experiments.The accumulation of pepper varieties was used as the research object,and the orthogonal experimental design was adopted to study the remediation effect of different characteristic materials on moderately Cd-contaminated yellow soil through pot experiments,and then to condense the technical model suitable for the safe utilization of moderately Cd-contaminated yellow soil in Guiyang.The main results of the study are as follows:（1）In the indoor soil culture test,compared with the control,the 9materials could increase soil p H,organic matter content,available phosphorus content,and reduce soil available Cd content,among which calcium magnesium phosphate fertilizer,corn straw biochar,Papula vulgaris Stone had the most significant passivation effect on Cd（P<0.05）,and the three reduced soil available Cd content by 74.32%-85.40%,61.98%-83.08%,69.46%-82.84%,at the same time,the addition of 5%the passivation effect was significantly better than 3%and 1%（P<0.05）.（2）In the pepper variety screening test,the absorption and accumulation of Cd by different pepper varieties were significantly different（P<0.05）,which was affected by the Cd stress level and the variety.The total dry weight of roots,stems and leaves of varieties P2,P6,P8,P9,P11,P14,P15,and P18 increased with the increase of Cd stress level,and reached the maximum at 20 mg·L^-1.It maintained a good growth state under stress,was less inhibited by Cd stress,and had strong tolerance to Cd,among them,P2（Gui La 303F₁）,P11（Kexin Hongfu）,P14（Gui Nong Peak）for Cd enrichment coefficients were 1.223-1.365,0.945-0.501,0.774-1.159,and transport coefficients were 1.416-1.498,0.579-0.739,0.577-1.048,which were ideal low Cd accumulation among the 18 tested varieties Varieties of peppers.（3）In the pot experiment,the overall level of Cd content in pepper fruits was P2（Gui La 303F₁）>P14（Gui Nong Peak）>P11（Kexin Hongfu）.According to the national food safety standard（GB2762-2017）,the Cd content of pepper fruit of Guila 303F₁ did not exceed the standard in treatment groups 3,5,6,7,8,and 9,and treatment groups 7 and 9 were significantly lower than other treatment groups（P<0.05）,the Cd content of Kexin Hongfu pepper fruit did not exceed the standard in all treatment groups,and the treatment group 9 had the most significant effect（P<0.05）,the Cd content of Guinong Peak pepper fruit only exceeded the standard in treatment group 12,and treatment group 12 exceeded the standard.Groups3,5,7,and 9 had more significant reduction effects than other treatment groups（P<0.05）.（4）In the pot experiment,compared with the control,under the 12treatment groups,the proportion of soil exchangeable Cd content decreased by 21.20%-75.64%,and the proportion of residual Cd content increased by75.42%-206.06%,The Cd content decreased by 6.23%-39.80%,reducing the bioavailability of soil Cd,the soil p H increased by 0.46-1.68 units,the organic matter content increased by 75.93%-128.44%,and the available phosphorus content increased by 9.19%-299.66%.Among them,treatment groups 7 and 9 had significant effects.（5）The results of variance and range analysis of orthogonal test showed that calcium magnesium phosphate fertilizer,corn straw biochar and palygorskite were the factors that significantly increased soil p H（P<0.05）,corn straw biochar was the factor that significantly increased soil organic matter content（P<0.05）,calcium magnesium phosphate fertilizer was the factor that significantly increased soil available phosphorus content（P<0.05）,calcium magnesium phosphate fertilizer,corn stalk biochar,and palygorskite were the factors that significantly reduced soil available Cd content（P<0.05）.（6）In the moderately Cd-contaminated farmland soil（yellow soil）,the safe production of pepper can be achieved by replacing the planting of Cd low-accumulation Chaotian pepper（Kexin Hongfu）,combined with soil passivation conditioning technology（5%calcium magnesium phosphate fertilizer+5%corn straw biochar+5%palygorskite or 5%calcium magnesium phosphate fertilizer+1%corn straw biochar+3%palygorskite）,it can also achieve Safe Production.