Soil Microbial Community Changes in a Field Treatment with Chlorotoluron, Flufenacet and Diflufenican and Two Organic Amendments

Carlos García-Delgado,María José Carpio,María Sonia Rodríguez-Cruz,María Jesús Sánchez-Martín,Jesús María Marín-Benito

doi:10.3390/agronomy10081166

Carlos García-Delgado, María José Carpio + Show 3 more

Open Access

https://doi.org/10.3390/agronomy10081166

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Abstract

The soil microbial activity, biomass and structure were evaluated in an unamended (S) and organically amended soil treated with two commercial formulations of the herbicides chlorotoluron (Erturon®) and flufenacet plus diflufenican (Herold®) under field conditions. Soils were amended with spent mushroom substrate (SMS) or green compost (GC). Soil microbial dehydrogenase activity (DHA), biomass and structure determined by the phospholipid fatty acid (PLFA) profiles were recorded at 0, 45, 145, 229 and 339 days after herbicide treatment. The soil DHA values steadily decreased over time in the unamended soil treated with the herbicides, while microbial activity was constant in the amended soils. The amended soils recorded higher values of concentrations of PLFAs. Total soil microbial biomass decreased over time regardless of the organic amendment or the herbicide. Herbicide application sharply decreased the microbial population, with a significant modification of the microbial structure in the unamended soil. In contrast, no significant differences in microbial biomass and structure were detected in S + SMS and S + GC, untreated or treated with herbicides. The application of SMS and GC led to a significant shift in the soil microbial community regardless of the herbicides. The use of SMS and GC as organic amendments had a certain buffer effect on soil DHA and microbial biomass and structure after herbicide application due to the higher adsorption capacity of herbicides by the amended soils.

Highlights

Pesticides are used intensively in modern agriculture to increase and protect crop yields [1,2].their increasing use poses a potential hazard for the environment due to their persistence in soil, their toxicity to non-target organisms, and the increase in resistant species [3,4]
analysis of variance (ANOVA) performed with time and soil management as factors for each herbicide separately indicated that this interaction was only significant for chlorotoluron (p = 0.000), with higher amounts in spent mushroom substrate (SMS)-amended soils than in unamended ones, but there were no significant differences for flufenacet (p = 0.3322) (Table 3)
The simultaneous application of green compost (GC) or SMS as organic amendments and the herbicides chlorotoluron, flufenacet, and diflufenican in an agricultural soil at field scale had little effect on the biological parameters that were tested in the soil microbial community

Summary

Introduction

Pesticides are used intensively in modern agriculture to increase and protect crop yields [1,2].their increasing use poses a potential hazard for the environment due to their persistence in soil, their toxicity to non-target organisms, and the increase in resistant species [3,4]. The presence of certain pesticides and their degradation products may alter the functional balance of the soil ecosystem, as they may promote, inhibit or even have no effect on the growth of most soil-dwelling microorganisms when applied at agronomical rates [2,5] They may have a positive, negative or no effect on the structure and diversity of microbial communities and soil enzymatic activities [1,6,7]. The use of organic amendments rich in nutrients and organic matter (OM) is a common practice in agriculture and soil remediation processes [4,8,9,10] This practice is often used to increase crop yields, improve soil quality and fertility, preserve the soil from degradation, mitigate pesticide leaching, and enhance soil microbial activity [6,11].

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