Remediation Of Low Cadmium-polluted Cultivated Land By Several Crop Rotation Systems

Phytoremediation,the use of plants to extract toxic metals from contaminated agricultural soils,has emerged as a cost effective environment friendly clean up alternative,but phytoremediation without economic revenue is unfeasible for land owners and farmers.Therefore,it is the key to select the crops with certain economic value in the process of phytoremediation.This field experiment analyzed the phytoremediation effects of three rotation systems in low Cd-contaminated farmland and the food safety in this paper.Potato-oilseed crop-rape/flax,potato-legume crop-rape/flax,potato-sorghum crop-rape/flax rotation patterns were set.The representative crops of oil crops（sesame,peanut,oil and sunflower）,legumes crops（big black beans,urad dal and yellow beans）,sorghum crops（dalishi,gangliangjiezi and jinlong）were selected for rotation.The aim is to screen the crops with tolerance and enrichment ability to cadmium.To explore the remediation potential of ten crop rotation systems for heavy metals.Search for suitable plant rotation systems to remediation heavy metal contaminated farmland.The experiment result expresses:（1）In these crops,flax has a strong accumulation capacity for heavy metals,and the total amount of cadmium extracted is 25.7 g·ha^-1,followed by jinlong and oilseed sunflower,and the total amount of cadmium extracted is 22.29 g·ha^-1 and21.53 g·ha^-1,respectively.Flax has a strong tolerance and enrichment effect on cadmium.Although the biomass of flax is low,the cadmium concentration in each part is high,up to 3.26 mg·kg^-1.（2）The growth of the experimental crops were not affected at all in the area with mild cadmium contamination.The potato-peanut-flax rotation system was the best extraction system among the ten system,with 54.86 g·ha^-1 and a remediation efficiency of 6.12%.The total amount of cadmium extracted from flax in this rotation system was the largest,and the total amount of cadmium extracted from flax in this rotation system was significantly higher than that from flax in other rotation system.Secondly,the potato-jinlong-flax rotation system also has a strong extraction capacity to remove 51.57g·ha^-1.（3）Considering the feasibility of using potato-peanut-flax and potato-jinlong-flax rotation to remediation the Cd-polluted farmland in liling.The cadmium concentration of the edible part of the potato that the tuber,is 0.23 mg·kg^-1and does not exceed the general standard for contaminants and toxins in food and feed（CODEX STAN 193-1995）.Flax has strong ability of enrichment of heavy metals,and most of their production for non-food applications/products.Peanut fruit by oil extraction solvent,accord with national oil health standard GB2716-2005(≤0.1mg·kg^-1).After harvest,the products of jinlong sorghum do not enter the food chain,and can be used as the raw material to produce bioethanol,producing certain economic benefits.（4）Potato-peanut-flax and potato-jinlong-flax rotation system can not only absorb cadmium in the soil,but also bring some economic benefits to local farmers,cadmium slightly polluted farmland to achieve production and remediation.