Cadmium content of swedish carrots and the influence of soil factors

Abstract

Over a 2-year period, carrots and surface soil samples (0-25 cm) from commercial fields in Sweden were collected in order to determine the variations in carrot cadmium (Cd) concentration and determine how they are influenced by soil factors. Differences between varieties with respect to Cd concentration were also determined in two field trials. The Cd content of carrots averaged 0.30 mg kg-1 dry matter (DM), but the range was large (0.06-0.85 mg kg-1 DM). Soil samples and corresponding carrot samples were divided into two groups: soils with a low organic matter content (< 12%) and soils with a higher content (≥ 12%). The soil factor best predicting carrot Cd concentration was surface soil pH (low organic matter, r2= 0.51; high organic matter, r2= 0.77). In a multiple regression analysis, soil pH, organic C content and soil Cd content (2M HNO3-extractable) together explained 62% (low organic matter) and 74% (high organic matter) of the total variation in Cd concentration in carrots. There were no significant differences between varieties with respect to Cd concentration in carrots.