FIG. 1.

Confirmation of [¹³C]benzoic acid metabolism measured as net ¹³CO₂ respiration from the agricultural field study site. ¹³CO₂ was produced from soils receiving 5 doses of 100 μg [¹²C]benzoic acid (•), 4 doses of 100 μg [¹²C]benzoic acid and a final 100 μg dose of [¹³C]benzoic acid (▪), or 5 doses of 100 μg [¹³C]benzoic acid (×). The percentage in parentheses shows the proportion of the total added ¹³C recovered as ¹³CO₂ from the treatment receiving a single dose of [¹³C]benzoic acid. Experimental values represent the mean and standard deviation of triplicate samples.