Transfert des éléments traces dans le système sol-plante : influence d’apports de matières organiques sur des sols agricoles non contaminés et contaminés

Details

Supervisors

Agnan, Yannick ; Arbalestrie, Bryan

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences et technologies de l'environnement, à finalité spécialisée

Abstract

enTrace elements are chemical elements present in low concentrations in all environments. However, they can have toxic effects above certain thresholds, making it necessary to assess their transfer from the soil to the plant, the preferred route for nutrition. The study of the factors controlling the dynamics of these elements is therefore necessary. The objective of this thesis is to evaluate: (1) the transfer of trace elements in the soil-plant system and (2) the influence of the addition of organic matter (green waste compost, bovine manure and intercrop cover) on this transfer. For this purpose, a greenhouse experiment was carried out on uncontaminated (Marbaix) and contaminated (Sainte-Walburge, Bressoux and Aubange) Belgian agricultural soils. To this end, a characterisation of the soils and the organic matter applied, as well as the analysis of the concentrations of trace elements in the soils, the plant (Zea mays) and the organic matter were carried out. The results obtained show (1) an influence of the soil properties and its origin on the availability of trace elements in the studied soils. The extractability of elements of anthropogenic origin is higher than for elements of natural origin, but their mobilisation depends on the nature of the elements considered. Furthermore, (2) the transfer of trace elements in the soil-plant system depends on the speciation and mobility of the trace elements, their physiological role(s) and the level of soil contamination. In general, micronutrients, such as Zn and Cu, are more transferred to plants than strict contaminants. It is also noted that plants accumulate strict contaminants at the root level, whereas for micronutrients it depends on their availability. In contaminated soils, plants show higher concentrations of trace elements, but relatively lower transfer than in uncontaminated soils. Finally, (3) the effect of organic matter input on the transfer of trace elements in the soil-plant system is soil and trace element specific. Some elements, such as Cr, have no effect for any organic matter tested, while others, such as Zn and Cu, show increases or decreases in transfer with organic matter input.