Pedosphere 35(6): 995--1004, 2025
ISSN 1002-0160/CN 32-1315/P
©2025 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Effects of sulfur fertilizers applied at agronomic rates on cadmium availability in agricultural soils: Insights from a batch experiment |
Agathe VIDAL, Christophe NGUYEN, Noémie JANOT, Pierre EON, Cécile CORIOU, Jean-Yves CORNU |
| Interactions Sol Plante Atmosphere (ISPA), Bordeaux Sciences Agro, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement ` (INRAE), Villenave d'Ornon 33140 (France) |
| ABSTRACT |
| Cadmium (Cd) is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops, notably in cereal grains. This study investigated the extent to which sulfur (S) fertilization increases the availability of Cd in a calcareous (Calc) and a non-calcareous (Ncalc) soil. Changes in Cd availability and speciation were monitored over a 21-d incubation period, along with changes in pH and the concentrations of sulfate, nitrate, calcium, magnesium, aluminum (Al), manganese (Mn), and nickel (Ni) in the potassium nitrate (KNO3) extracts, after the addition at agronomic rates of three forms of S fertilizers: elemental S (S(0)), potassium sulfate (K2SO4), and ammonium sulfate ((NH4)2SO4). Elemental S did not increase the Cd concentration in the KNO3 extracts of either soil due to its too limited oxidation to sulfates. The two sulfate fertilizers had contrasting effects on Cd concentration depending on the nature of the counter cation (K+ or NH4+). While K2SO4 caused almost no change in Cd concentration in either soil, (NH4)2SO4 increased Cd concentration in both soils. The nitrification of NH4+ reduced soil pH, thereby increasing the concentrations of Cd, Al, Mn, and Ni in the Ncalc soil over time, as evidenced by the strong negative correlations between soil pH and the concentrations of these four elements in the KNO3 extract after 21 d. In the Calc soil, the mechanism of Cd concentration increase after (NH4)2SO4 addition was more difficult to understand and could result from the proton-mediated alteration of Cd-bearing phases such as carbonates, following ammonia (NH3) volatilization. The relevance of these results for the S fertilization of cereals in Cd-contaminated soils is discussed. |
| Key Words: ammonium sulfate|calcareous soil|cereals|fertilization|nitrification|trace metals |
| Citation: Vidal A, Nguyen C, Janot N, Eon P, Coriou C, Cornu J-Y. 2025. Effects of sulfur fertilizers applied at agronomic rates on cadmium availability in agricultural soils: Insights from a batch experiment. Pedosphere. 35(6): 995-1004. |
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