Measuring CO2 Production Using Soda Lime:

Data Form for Samples

For use with Protocol 8c: Measuring the rate of CO2 production

Complete this form for each soil sample.

Name(s)  ______________________                     Today’s Date  __________________

Soil sample ID number ___________           Sampling Date  _________________

Soil sampling location ___________________________________________________

Type of area sampled (such as forest or field) ________________________________

Soil description_________________________________________________________

Date and time soda lime incubation started  ______________________

Date and time soda lime incubation ended  _______________________

Total # days incubation (should be 2 days) ________

Protocol 8c, Part 2: Prepare Soil Samples

Before Incubation:

 Weight of container (without lid) (G) = _____________ g Weight of container (without lid) and soil (H) = _____________ g Total soil weight (I) = H – G = _____________ g

Protocol 8c, Part 3: Prepare Soda Lime

Before Incubation:

 Weight of petri dish bottom = _____________ g Weight of dish and soda lime before drying = _____________ g Weight of dish and dried soda lime (J) = _____________ g

Protocol 8c, Part 5: Calculate the Amount of CO2 Produced

After incubation and re-drying of the soda lime:

 Weight of dish and soda lime = _____________ g Weight of dish and soda lime after re-drying (K) = _____________ g Sample soda lime weight gain (L) = K – J = _____________ g

Calculating the rate of CO2 production:

1) Calculate the corrected weight gain for soda lime:

 Corrected soda lime wt gain = Sample soda lime wt gain – Blank soda lime wt gain Y = L – C ________ g _______ g ______ g

The answer will be in grams of CO2 produced. For use in the final equation, you’ll need to convert this to milligrams:

_________ g x 1000 mg/g = ____________mg CO2

2) Calculate the dry weight of the total soil sample (using soil weights from this form and % moisture from Part 1, Step 6 on the Data Form for Soil Moisture Content):

Dry weight = total soil wt – (moisture content x total soil wt)

Z = I – (moisture content x I)

____ g = _____ g – (______  x  ______ g)

This answer will be in grams of dry soil. For use in the final equation, you’ll need to convert it to kilograms:

_________ g x 0.001 kg/g = ____________kg dry soil

3) Calculate the rate of CO2 production in terms of milligrams CO2 produced per day per kilogram of dry soil. Use your answers from the previous two steps in place of the Xs in this equation:

CO2 production rate = _Y mg CO2 x 1.69/2 days = __________ mg CO2/day/kg dry soil

Z kg dry soil

Note: If your exposure time was not 2 days, replace the 2 in this equation with the correct # days.