Adsorption of tetraconazole by organic residues and vineyard organically-amended soils
Spain is the country with the largest wine-producing area in the EU and its productivity is largely controlled applying fungicides. However, residues of these compounds can move and contaminate surface and groundwater. The objective of this work was to evaluate the capacity of bioadsorbents from different origin to adsorb and immobilize tetraconazole by themselves or when applied as organic soil amendment, and to prevent soil and water contamination by this fungicide. The adsorption of tetraconazole by 3 organic residues: spent mushroom substrate (SMS), green compost (GC) and vine pruning sawdust (VP), as well as by vineyard soils unamended and amended individually with these residues at 1.5% (w/w) was evaluated using the batch equilibrium technique. Two vineyard soils from La Rioja were selected (S1-sandy loam, 0.26% OC; and S2-clay loam, 0.69% OC). Freundlich Kf adsorption constants of tetraconazole (3.6-19.2) by unamended and amended soils increased in the order: S1 < S2 < S2+GC < S2+VP < S1+VP ≈ S1+GC < S2+SMS < S1+SMS; and for the residues in the order: GC < VP < SMS. The Kf values of amended soils, especially for SMS-amended soils, were higher than those of unamended soils, due to their higher OC content. The application of organic residues to S1 soil increased its Kf value between 3.7-5.4 times, and that of S2 soil up to 2.7 times. However, the Kf values of S1 soil amended with the different organic residues were higher than those of amended S2 soils, despite their lower OC content. Therefore, physicochemical characteristics of soils different from OC (pH, carbonates, clay content, etc.) may also play an important role on the adsorption of tetraconazole by amended soils as observed for other fungicides.
Acknowledgements: We give thanks to Project TED2021-129962B-C41, funded by MCIN/AEI/10.13039/501100011033/ and the European Union (NextGenerationEU/PRTR).
Issue: ICGWS 2023
1 Institute of Natural Resources and Agrobiology of Salamanca (IRNASA, CSIC), Cordel de Merinas 40-52, 37008 Salamanca, Spain.
2 Agriculture and Food Department, University of La Rioja, Madre de Dios 51, 26006 Logroño, Spain.