Soil amendment affects Cd uptake by wheat — are we underestimating the risks from chloride inputs?

• Published in: The Science of the total environment 2016-06, Vol.554-555, p.349-357
• Main Authors: Dahlin, A. Sigrun, Eriksson, Jan, Campbell, Colin D., Öborn, Ingrid
• Format: Article
• Language: English
• Subjects: Agricultural Science; Agriculture - methods; Cadmium - analysis; Cadmium - metabolism; Cadmium mobility; Chloride complexation; Chlorides - chemistry; Circular economy; Environmental Monitoring; Fertilizers; Human health; Jordbruksvetenskap; Markvetenskap; Nutrient recovery; Soil - chemistry; Soil Pollutants - analysis; Soil Pollutants - metabolism; Soil Science; Triticum - metabolism; Triticum aestivum; Wastes
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.02.049

Many parts of the world are investigating the efficacy of recycling nutrient resources to agriculture from different industry and domestic sectors as part of a more circular economy. The complex nature of recycled products as soil amendments coupled to the large diversity of soil types and their inherent properties make it difficult to optimize the benefits and minimize the risks from potentially toxic elements often present in recycled materials. Here we investigated how wheat grain cadmium (Cd) concentration was affected by soil amendments, namely human urine and biogas digestate compared to traditional farm manures and mineral fertilizers. We show that Cl− inadvertently added to soils with e.g. urine or biogas digestate strongly increased crop Cd concentrations, largely by mobilizing inherent soil Cd. This resulted in wheat grain Cd levels that could result in exceeding recommended WHO limits for dietary intake. This was evident even in soils with low inherent Cd content and when Cd inputs were low. The future of a circular economy that helps to underpin global food security needs to ensure that the effects of applying complex materials to different types of agricultural land are fully understood and do not jeopardize food safety. Modified from Wivstad et al. (2009) [Display omitted] •High-Cl by-products used as soil amendments mobilize soil Cd.•Wheat grain Cd levels were found that could result in exceeding dietary intake limits.•Quality and risk assessment of by-products should include Cl effects.