Simazine application inhibits nitrification and changes the ammonia-oxidizing bacterial communities in a fertilized agricultural soil

Abstract

s-Triazine herbicides are widely used for weed control, and are persistent in soils. Nitrification is an essential process in the global nitrogen cycle in soil, and involves ammonia-oxidizing Bacteria (AOB) and ammonia-oxidizing Archaea (AOA). In this study, we evaluated the effect of the s-triazine herbicide simazine on the nitrification and on the structure of ammonia-oxidizing microbial communities in a fertilized agricultural soil. The effect of simazine on AOB and AOA were studied by PCR-amplification of amoA genes of nitrifying Bacteria and Archaea in soil microcosms and denaturing gradient gel electrophoresis (DGGE) analyses. Simazine [50 μg g(-1) dry weight soil (d.w.s)] completely inhibited the nitrification processes in the fertilized agricultural soil. The inhibition by simazine of ammonia oxidation observed was similar to the reduction of ammonia oxidation by the nitrification inhibitor acetylene. The application of simazine-affected AOB community DGGE patterns in the agricultural soil amended with ammonium, whereas no significant changes in the AOA community were observed. The DGGE analyses strongly suggest that simazine inhibited Nitrosobacteria and specifically Nitrosospira species. In conclusion, our results suggest that the s-triazine herbicide not only inhibits the target susceptible plants but also inhibits the ammonia oxidation and the AOB in fertilized soils.

Land Spreading of Wastewaters from the Fruit-Packaging Industry and Potential Effects on Soil Microbes: Effects of the Antioxidant Ethoxyquin and Its Metabolites on Ammonia Oxidizers

“…3b and c). This is in line with previous studies which reported effects of pesticides on AOMs only upon exposure to levels well above the recommended rates (55,56). It should be noted that for the pesticides used in FPP, there are no recommended dose rates for soil application, and their effects were assessed based on application rates calculated according to a realistic wastewater disposal scenario employed by FPP in Europe.…”

Responses of Limagne “Clay/Organic Matter-Rich” Soil Microbial Communities to Realistic Formulated Herbicide Mixtures, Including S-Metolachlor, Mesotrione, and Nicosulfuron

“…The decrease of AOA-amoA gene copies observed in mixture microcosms at day 28 could explain the peak of ammonium observed the same day, as a result of a lack in nitrification processes. This effect has already been observed for the s-triazine herbicide simazine, in a soil microcosm study (Hernández et al 2011). However, no significant linear correlations could be made between AOA-amoA gene copies and ammonium at day 28, even if a similar trend of decrease occurred (Supplementary data 5A).…”

“…From a global point of view, these communities appeared to be quite resistant to the onefold field rate doses of these herbicides regardless the number of chemicals, as underlined by many authors for single chemicals use (Accinelli et al 2002;Crouzet et al 2010;Wainwright 1978). The only recorded effects were transients and mainly related to the N-cycle communities, already known to be sensitive to certain class of herbicides (e.g., Damin and Trivelin 2011;Hernández et al 2011), with firstly an increase of ammonification and an inhibition of nitrification followed by an increase of denitrification. However, the lack of activities information restricted our conclusions on these communities, which highlighted the need to deepen the studies on Ncycle activities.…”

Functional and structural responses of soil N-cycling microbial communities to the herbicide mesotrione: a dose-effect microcosm approach

“…Some studies have reported contrasting responses of nitrification and denitrification to high herbicide doses (Carlisle and Trevors 1986;Andersch and Anderson 1991;Pell et al 1998); nonetheless, they did not investigate if nutrient shifts or microorganism abundances can explain the activity shifts. Although the influence of certain edaphic factors on bacterial ammonia oxidizers (AOB) and archaeal ammonia oxidizers (AOA) has recently attracted attention (Tourna et al 2008;Erguder et al 2009;Prosser and Nicol 2012), little is known about their implication in the nitrification responses to herbicides (Hernandez et al 2011) or fungicide stress (Muñoz-Leoz et al 2011;Puglisi et al 2012).…”