Utilisation de composés carbonés afin de diminuer la concentration de cadmium dans des végétaux comestibles de Nouvelle-Zélande

Cadmium (Cd) is a non‐essential trace element which is toxic at high concentrations. Cd is added to New Zealand soils through superphosphate fertilizer. The Cd is then absorbed by vegetables and may exceed the limit of 0.1 mg/kg value, thus leading to economic and health risks. Previous studies have shown that lignite can significantly reduce the absorption of Cd by pasture, and that this effect is dependent on soil type. In addition, other studies have shown that compost can reduce the absorption of some metals. The effects of these amendments were tested on Cd uptake by vegetables, as they are more sensitive to the toxic effects of Cd than pasture grass. We studied the absorption of Cd in vegetables grown in two New Zealand soils with and without Cd spiking. We also studied the effect of an amendment with compost and two amendments with lignite. The results show that the amendment with compost reduced the absorption of Cd in all plants studied. The decrease of the absorbed concentration was up to 60% in some cases. Amendments with lignite showed significant decreases and one significant increase in the concentration of Cd in vegetables. The decreases of Cd observed in the various amendments were not typically related to the extractable Cd concentration or to the soil pH. Finally, we observed no clear pattern concerning the absorption of other elements. Because of the highly variable composition of compost, a comprehensive study with different types of compost is recommended to better understand the effects of compost on Cd uptake by vegetables. In addition, a study on the persistence of compost into the soil should also be performed.