Repeated annual glyphosate applications may impair beneficial soil microorganisms in temperate grassland

DRUILLE M.; GARCÍA PARISI P.A.; GOLLUSCIO R.A.; CAVAGNARO F.P.; OMACINI M.

AGRICULTURE, ECOSYSTEMS AND ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 230 p. 184 - 190

0167-8809

Due to the worldwide use of the herbicide glyphosate, there is agrowing interest in understanding its impact on beneficial soilmicroorganisms. However,most studies have been focused on evaluating the effects on thesemicroorganisms of a single application in agricultural crops, despite the factthat repeated applications is a common scenario in different productionsystems. We evaluated the impact of four annual glyphosate applications onarbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE) andfree-living diazotrophs in a temperate grassland. Sub-lethal (0.8 l ha1) andrecommended field doses (3 l ha1) were analyzed. AMF viable spores andfree-living diazotrophs densities were reduced by 56% and 82% respectively,after the fourth application even at sublethal dose. While total AMF rootcolonization in Lolium arundinaceum was not affected among treatments,arbuscules percentage was reduced in plants grown in plots treated with 3 l ha1.A similar response was detected in DSE root colonization. Considering the rolethey have in structuring plant communities, these deleterious effects onbeneficial soil microorganisms might negatively impact on grasslandproductivity and diversity. It is necessary to investigate the resilience ofthe microbial community in order to develop a long-term strategic management ofglyphosate applications that would achieve the desired objectives without irreversiblyaffecting soil biota.