Effects of cadmium concentration in soil and soil improvement on cadmium uptake by vegetables
2006
Kikuchi, S.(National Inst. of Vegetable and Tea Science, Tsukuba, Ibaraki (Japan)) | Yamazaki, H. | Kimura, T. | Miyaji, N. | Murakami, H.
To reveal variations of Cd content in vegetables. Cd content was measured in six leaf vegetables and three fruit vegetables planted in Cd-contaminated fields. Cd content was different among the vegetable species investigated. Especially, Cd content in the spinach samples were higher than those in the other leaf vegetables. Although the vegetable Cd content showed no relation with Cd concentration in the soils (extracted by 0.1M HCl), it had an inverse relationship to the soil pH. This result suggests that the application of alkali materials on fields can be effective to reduce Cd uptake by vegetables. We verified the effects of soil improvement on Cd-contaminated fields on the suppression of Cd uptake by vegetables. Cd content in three leaf vegetables (spinach, komatsuna, garland chrysanthemum) was reduced to about half the control level, below the CODEX standard (0.2mg kg(-1)), with the soil turning method (the depth of 50cm). Cd content in the spinach planted on Cd-contaminated soil with soil dressing (40cm thickness) was the same (0.11mg kg(-1)) as on non-contaminated soil, because spinach roots could not penetrate into the soil below the depth of 40cm. These results indicate that the soil turning method (the depth of 50cm) and dressing soil (40cm thickness) are effective to reduce Cd content in spinach. In addition, it was demonstrated that the insertion of root-proof sheet between the dressed soil and the contaminated soil could assist in reduction of Cd content in spinach.
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