Microbial Respiration in Soils of the Argentine Pampas after Metsulfuron Methyl, 2,4‐D, and Glyphosate Treatments

Abstract

Short-term response of microbial respiration after treatment with different doses of the herbicides mesulfuronmethyl (MET), 2,4-D, and glyphosate (GLY) was studied in microcosms of soils collected in three agricultural sites of the Southerns Pampas region, Buenos Aires Argentina. The influence of diammonium phosphate on carbon dioxide evolution when applied with the highest doses of the herbicides, was also investigated. MET had no effect on microbial respiration of an acidic soil of San Roman (pH 6.06), even at the highest rate. However, MET inhibited microbial respiration in soils of Bordenave (pH 7.4) at rate of 0.1 mg /Kg soil. Low applications rates of GLY and 2,4-D, produced only transitory effects on CO2 evolution whereas the addition of highest doses of these herbicides stimulated microbial activity. On the other hand, trhe addition of fertilizer to soil treated with a high dose of GLY temporarily inhibited CO2 release.