FIG. 3.

Field respiration experiment verifies that interpolated (inferred) ¹³CO₂ matches that of measured controls. In the field release open-bottom soil cover assay, treatments were with water only and 400 μg of [¹³C]glucose. The percentage in parentheses shows the proportion of the total substrate recovered as ¹³CO₂. The inferred background was 1.17% of the ¹²CO₂ in the ¹³C-glucose treatment. Each treatment was performed in triplicate; error bars indicate standard deviations. (Note: the ambient temperature during this assay was ∼10°C cooler than for the ones shown in Fig. 4.)