Research On Soil Conditioning Technology For Safe Potato Production In Cadmium-contaminated Areas

The soil heavy metal cadmium(Cd)in the karst geological high background area of northwestern Guizhou is seriously polluted,posing a threat to the quality and safety of the main crop potato.At present,the main technology for the safe production of contaminated farmland crops is the soil passivation conditioning technology.In this study,organic conditioning agents biochar,humic acid,and inorganic conditioning agents lime,red mud,and phosphate rock powder were selected.Single factor test and orthogonal test are used to study the safe use of different p H and pollution levels and strictly control yellow-like soil and yellow-brown soil,and Weiyu No.5 potato was used for field test verification.conclusion as below:(1)The single application of the conditioner reduced the content of available Cd(CaCl2-Cd)in the soil to varying degrees.In the safe use of yellow-like soil,lime1%,red mud 1%,phosphate rock powder 0.5%,humic acid 3%,biochar 1% reduced by 93.2%,87.5%,56.7%,74.4%,83.2%;In the strict control of yellow-like soil,the3% treatment of lime,red mud,and phosphate rock powder,the 5% treatment of humic acid and biochar reduced 99.3%,92.5%,45.6%,87.1% and 51.8%respectively;In the safe use of yellow-like brown soil,the 3% treatment of lime,red mud,and phosphate rock powder,the 5% treatment of humic acid and biochar reduced 99.2%,84.5%,44.3%,85.5%,and 67.9%,respectively;In the strict control of yellow brown soil,the 3% treatment of lime,red mud,and phosphate rock powder,the 5% treatment of humic acid and biochar reduced the reduction by 99.4%,88.2%,81.6%,72.7%,and 66.4%,respectively.(2)Orthogonal test results show that in the safe use of soil,humic acid +biochar + phosphate rock powder(5:3:5)treatment effective Cd reduced by 95.3%,humic acid + biochar + lime + Phosphate rock powder(5:3:5:3)can reduce Pb by88.2%.In strictly controlled soils,the humic acid + phosphate rock powder + red mud(3:3:3)treatment has a Cd reduction effect of 99.2%,and the biochar + red mud(3:5)treatment has a Pb reduction effect of 95.1%.According to the test results,the range analysis was carried out,and the optimal ratio of the optimal conditioner for different quality types of soil was deduced,and the field test was carried out to verify it.(3)Potato field test results showed that after the application of the three best conditioners,the yield of potato increased by 19.3,27.4% and 1.4%,and the tuber Cd decreased by 17%～49% on the safe use of soil.On controlled soils,potato yield increased by 29.7,14.2%,and 2.2%,tuber Cd decreased by 39% to 48%;potato tubers on both soils reached the national food safety limit standard(GB2762-2017).The organic-inorganic ratio conditioning technology can achieve the ideal heavy metal passivation effect.It is an effective and safe production technology for heavy metal contaminated soil in the high geological background and pollution superimposed area of northwestern Guizhou.