In Blount0 soil, the rate of respiration was not affected by the rate of glyphosate-C added (Fig. 2). The slope of the regression line was negative but this was not significantly different than the control. However, the low coefficient of determination (R2 = 0.06) indicates that there was a poor linear relationship between C added by glyphosate and respiration. The Blount1 soil showed a moderate relationship between glyphosate carbon added and CO2-C evolved (R2 = 0.80) (Fig. 2). The slope of the regression line was less than 1 (0.89), suggesting that the C added as glyphosate was not completely mineralized. In the Bennington2 soil, there was a strong relationship between glyphosate C added and CO2-C evolved (R2 = 0.99) (Fig. 2). The slope of the regression line was greater than 1 (1.39), indicating that the glyphosate stimulated microbial activity beyond glyphosate decomposition.