Phytoavailability-based threshold values for cadmium in soil for safer crop production

• Published in: Ecotoxicology and environmental safety 2020-09, Vol.201, p.110866, Article 110866
• Main Authors: Kim, Hyuck Soo, Seo, Byoung-Hwan, Owens, Gary, Kim, Young-Nam, Lee, Jae-Hwang, Lee, Mina, Kim, Kwon-Rae
• Format: Article
• Language: English
• Subjects: Agricultural product; Cadmium - analysis; Cadmium - metabolism; Crop Production; Crops, Agricultural - metabolism; Food Safety; Glycine max - metabolism; Heavy metal; Oryza - metabolism; Phytoavailability; Sesamum - metabolism; Soil - chemistry; Soil management policy; Soil Pollutants - analysis; Soil Pollutants - metabolism; Threshold values
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2020.110866

The phytoavailability of heavy metals in soils is important for both food safety and environmental management. Hence soil metal phytoavailability threshold values need to be established based on a firm scientific basis. In this study, optimal Cd phytoavailability threshold values, were determined for bean, rice and sesame cultivated in 100 soils varying widely in soil chemical characteristics by comparing the soil Cd phytoavailability obtained using three commonly used extraction procedures. Subsequently, the transfer functions derived in this study, were used to establish soil Cd phytoavailability threshold value standard limits for each specific crop. In addition, independent experimental data were used to supplement the obtained soil phytoavailable Cd threshold value for rice. Soil phytoavailable Cd concentrations extracted by 1 M NH4NO3, 0.05 M EDTA and Mehlich3 solutions were each more significantly correlated with plant Cd concentrations than total soil Cd concentrations. Thus, the soil Cd phytoavailability threshold values proposed in this study provide a more effective means of ensuring safer agricultural food production. Therefore, it is recommended that current agricultural soil heavy metal management policy; which is based on total concentrations; should be changed to embrace soil metal phytoavailability for safer agricultural food production. •Soil cadmium phytoavailable threshold values (PA-Cd) were developed to secure crop safety.•For rice PA-Cd were 0.04 and 0.97 mg kg−1 using NH4NO3 and Mehlich3 extracts, respectively.•Adoption of PA-Cd increased the accuracy of predicting exceedance of crop Cd guidelines.•Accuracy increased from 45% based on total soil Cd up to 91% when using PA-Cd.