Responses of soil microbial biomass and enzyme activity to herbicides imazethapyr and flumioxazin

Mariane Pertile,Paul J Van Den Brink,Jadson Emanuel Lopes Antunes,Lucas William Mendes,Ademir Sérgio Ferreira Araujo,Fabio Fernando Araujo

doi:10.1038/s41598-020-64648-3

Mariane Pertile, Paul J Van Den Brink + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-64648-3

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Abstract

The use of herbicides is important for controlling weeds in crops. However, they can present impacts on soil properties, such as biological properties. In this study, we evaluated the responses of soil microbial biomass and enzymes activity to the application of the herbicides imazethapyr and flumioxazin and their mixture in an experiment under laboratory conditions, using soils with a different history of use. Soil microbial biomass C (MBC) decreased, while microbial biomass N (MBN) was not affected after the application of the herbicides as compared to the control. Soil respiration, respiratory quotient, and dehydrogenase (DHA) activity increased significantly after the application of the herbicides compared to the control. The hydrolysis of fluorescein diacetate (FDA) was not significantly different between the control and the herbicide treatments. The principal response curve showed the largest initial effects for the flumioxazin, followed by imazethapyr and their mixture. Flumioxazin had a different influence on soil respiration and respiratory quotient than imazethapyr and their mixture. Finally, the effects of herbicides on soil microbial biomass and enzymes are short-term as we observed recovery in the biological parameters over time.

Highlights

The use of herbicides is important for controlling weeds in crops
The microbial quotient (QM) did not show differences between the control and the herbicides treatments (Fig. 2A), while microbial biomass C (MBC):microbial biomass N (MBN) ratio decreased after the application of the herbicides as compared to the control in both H0 and H2 (Fig. 2B)
QM, and MBC:MBN ratio decreased at 15 days after herbicides application and increased at 30 and 60 days (Fig. 2)

Summary

Introduction

The use of herbicides is important for controlling weeds in crops. they can present impacts on soil properties, such as biological properties. Soil microbial biomass represents the active part of soil organic matter and is involved in several functions in soil, presenting a rapid turnover of soil C, N, and P; while enzymes are a suitable indicator of the catabolic activity of soil microorganism[6] These biological properties are highly sensitive to detect soil disturbance after the application of chemicals, such as herbicides[4,7,8]. Flumioxazin, that belongs to the N-phenylphthalimide chemical family, is a soil-applied herbicide recommended for broadleaf weeds control in soybean, peanut, and vineyard[13] It has a mode of action on the protoporphyrinogen oxidase[12], presenting anti-microbial effect and could inhibit some enzymes[14]

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