Does a decade of soil organic fertilization promote copper and zinc phytoavailability? Evidence from a laboratory biotest with field-collected soil samples

Laurent Céline, Bravin Matthieu, Crouzet Olivier, Lamy Isabelle. 2024. Does a decade of soil organic fertilization promote copper and zinc phytoavailability? Evidence from a laboratory biotest with field-collected soil samples. Science of the Total Environment, 906:167771, 13 p.

Résumé : Despite chronic contamination, long-term organic fertilization tends to decrease copper (Cu) and zinc (Zn) availability in agricultural soils. Root activities of crop plants can also induce substantial changes in rhizosphere chemistry and consequently in the Cu and Zn availability in the rhizosphere. The balance between these two drivers and the overall effect of organic fertilization on Cu and Zn bioavailability to plants (i.e., phytoavailability) remains a matter of debate. We assessed the effect of a decade of agronomically realistic organic fertilization on Cu and Zn availability in the rhizosphere and their phytoavailability. Using a laboratory biotest, Festuca arundinacea was exposed to 34 soil samples collected from three agricultural field trials that had received no, mineral, or organic fertilization for a decade. Dissolved organic matter (DOM) properties (i.e., concentration, aromaticity, and binding properties toward Cu), pH, and Cu and Zn availability (i.e., total dissolved concentration and free ionic activity) were determined in the rhizosphere solutions. Cu and Zn phytoavailability was measured as the plant uptake flux. Contrary to bulk soils, organic fertilization induced very few changes in the chemistry and Cu and Zn availability in the rhizosphere solutions compared to no and mineral fertilization. Consistently, Cu and Zn phytoavailability did not increase with organic fertilization, but it was mostly driven by soil properties rather than by fertilization. Despite increasing soil Cu and Zn contamination, a decade of soil organic fertilization did not increase Cu and Zn phytoavailability, presumably due to the root-mediated levelling of Cu and Zn availability in the rhizosphere.

Mots-clés Agrovoc : engrais organique, cuivre, fertilité du sol, chimie du sol, test biologique, zinc, rhizosphère, biodisponibilité, fertilisation, matière organique, relation plante sol

Mots-clés libres : Bioassay, Pore water, Potentially toxic element, Root interface, Structural equation modeling, Wastes

Classification Agris : F04 - Fertilisation
F61 - Physiologie végétale - Nutrition

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement européennes : European Commission, European Regional Development Fund

Agences de financement hors UE : Conseil Régional de La Réunion, Ministère de l'Agriculture et de l'Alimentation

Projets sur financement : (REU) Services et impacts des activités agricoles en milieu tropical

Auteurs et affiliations

• Laurent Céline, CIRAD-PERSYST-UPR Recyclage et risque (REU)
• Bravin Matthieu, CIRAD-PERSYST-UPR Recyclage et risque (FRA) ORCID: 0000-0002-1436-7837 - auteur correspondant
• Crouzet Olivier, INRAE (FRA)
• Lamy Isabelle, INRAE (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/606734/)

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