Remediation Of Cadmium Contaminated Soil With Shell Power Compound Fertilizer

Cadmium is a common heavy metal.In recent years,there have been many food safety accidents caused by cadmium pollution in soil,In this thesis,based on the passivation effect of shell powder on Cadmium in soil,reasonable use of shell powder to make remediation compound fertilizer,realize the integration of remediation and fertilization,change waste into treasure,reduce cost and increase efficiency.In this thesis,three different types of cadmium contaminated soil were taken as remediation objects,and the passivation effect of shell powder on cadmium in soil was verified by static culture and pot experiment.Tests show that adding 0.1%～0.2%shell powder to soil can effectively improve the pH value of acidic soil,On the 60th day of pot experiment,the reduction rate of available cadmium in soil was 37.8%～6.9%,and the average weight per plant of rape increased by 4.1%～12.8%.Based on the remediation effect of shell powder on cadmium in soil,the remediation compound fertilizers(No.F50,F100)were prepared according to the addition amount of shell powder of 50 kg·t-1 and 100 kg·t-1,and the physical and chemical indexes were detected and pot experiments were carried out simultaneously with the conventional compound fertilizer(F00).Test show the main indexes of F50 and F100 meet the requirement of national standard,Roundness,anti-caking performance,bulk density and the like are improved,which is beneficial to fertilizer production,storage and application.The percentage of water-soluble phosphorus in available phosphorus decreased,and F00,F50 and F100 were 87.6%,82.3%and 78.1%.The pH value increased slightly with the increase of shell powder,which were 6.05,6.20 and 6.62 respectively.Pot experiment showed that the soil pH value of different treatments F50 and F100 increased by 0.22 pH～0.54 pH unit on the 60th day.Compared with F00,the contents of available N,P,K and urease activity in soil treated by F50 and F100 were balanced and stable in the whole test cycle,which was beneficial to the sustainable and stable supply of nutrients.The total cadmium conversion rate in soil was 14d<28d<60d,and the total cadmium conversion rate of each treatment was 20.4%～25.9%in 60 d.The emergence rate of small rape treated with F00,F50 and F100 with lg·kg-1～3g·kg-1 was higher,the emergence rate of the three kinds of fertilizer 4g·kg-1 was poor.The average weight per plant of small rapeseed increased by 18.4%～51.7%in the 60th day,Chlorophyll content was positively correlated with fertilization amount,Chlorophyll content of F50 series has the most significant correlation with fertilization amount,with correlation coefficient R2=0.9675.Three kinds of fertilizers can inhibit the transfer of cadmium in stems,leaves and roots of small rape,Fertilize F50 and F100 with 1g·kg-1～4g·kg-1,the reduction rate of cadmium in roots was 19.2%～38.5%,and that in stems and leaves was 37.9%～51.7%,which was more significant than F00.In conclusion,compared with conventional fertilizer,shell powder compound fertilizer can effectively reduce the migration of cadmium in soil,prolong the fertilizer efficiency,and increase crop yield significantly.