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.