Effect of two broad-spectrum fungicides on the microbial communities of a soil subjected to different degrees of water erosion

ROMINA A. VERDENELLI; MARÍA F. DOMINCHIN; FLORENCIA M. BARBERO; CAROLINA PÉREZ-BRANDAN; ANTONIO AOKI; SILVINA VARGAS GIL; JOSÉ M. MERILES

APPLIED SOIL ECOLOGY

ELSEVIER SCIENCE BV

Año: 2023 vol. 190

0929-1393

The impact of both fungicide and water erosion on soil microbial communities has been little studied, and far lessin subhumid-dry climates. To help fill this knowledge gap, we evaluated the influence of two broad-spectrumfungicides applied to soil subjected to different degrees of water erosion on microbial population and function.Soil samples were taken from an experimental site under three water erosion levels: an agricultural land subjectedto minimum water erosion by terrace farming (MIN), an agricultural land subjected to moderate watererosion without terrace farming (MOD), and a land with no water erosion control treatment (non-eroded, NON).Three dosages of both carbendazim and iprodione were applied to microcosms, and the responses of microbialcommunity and function were examined after 30-day exposure. Phospholipid fatty acid (PLFA) analysis, soil enzymeactivities, and microbial abundances estimated by quantitative real-time PCR (qPCR) were used to evaluatethe impact of carbendazim and iprodione fungicides applied at three dosages on microbial community structureand enzyme activities. The lowest values of fluorescein diacetate hydrolase (FDA), dehydrogenase, urease, andglucosidase activities were registered in soil under moderate erosion, while the highest ones were observed innon-eroded soils. Both carbendazim and iprodione decreased C- and P-related activities, even when those fungicideswere applied at field rate doses. Thus, phosphomonoesterase, glucosidase, and xylosidase in soil treatedwith fungicides applied at recommended field rate decreased by 46 %, 61 %, and 34 % compared to soil withoutfungicide application. The lowest values of PLFA biomarkers for Gram-positive bacteria, Gram-negative bacteria,and arbuscular mycorrhizal fungi were registered in soils treated with the highest dose of both carbendazim andiprodione. Thus, Gram-positive bacteria, Gram-negative bacteria, arbuscular mycorrhizal fungi, and fungal PLFAbiomarkers in soils without fungicide application were about 36 %, 3 %, 47 %, and 82 % higher than those soilstreated with the highest doses of fungicides, respectively. In addition, the highest doses of fungicide applicationtended to greater decrease total PLFAs in both non-eroded and minimum eroded compared to moderate erodedsoils. Similarly, the response of bacterial and fungal populations to fungicide treatment was more pronounced innon-eroded soils than in eroded soils. This study illustrates how the interactions between fungicides and watererosion levels affect soil enzyme activities, microbial abundances, and microbial community structure in agroecosystems.