Hello,

I have a question regarding the correct calculation of CO2 from soil incubation experiments.

I incubated soils in an air-tight container and took air samples after multiple timepoints. I always collected 5 mL of headspace from the container/incubator and injected it straight into the IRGA.

Let's assume I have a CO2 flux of 1000 ppm per hour in sample 1. Do I need to divide it by 5 to account for the fact that I collected 5 mL of headspace? Or is that irrelevant because the concentration is always the same?

The part that confuses me is that I calculate the ppm from the IRGA output as area under the curve in R. If I inject 10 mL, rather than 5 mL, I have obviously a much higher curve. But is the ppm still the same because the curve is longer?

For the remaining calculations I used the following paper which gives a very good overview:

Soil heterotrophic respiration assessment using minimally disturbed soil microcosm cores

Article Soil heterotrophic respiration assessment using minimally di...