## MEASURING DECOMPOSITION USING SODA LIME DATA FORM 3: SAMPLES

Complete this form for each soil sample.

Name(s) _____________________________________ Today’s date __________________

Soil sampling ID number _________________________ Sampling date _______________

Soil sampling location _______________________________________________________

Type of area sampled (e.g., forest, schoolyard) ____________________________________

Soil description _____________________________________________________________

Date and time soda lime incubation started _______________________________________

Date and time soda lime incubation ended ________________________________________

Total # days incubation (should be 2 days) __________________________

# Protocol 4c, 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 wt (I)                       = H – G           = ____________ g

# Protocol 4c, 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 soda lime after drying (J)                 = ____________ g

Protocol 4c, Part 5. Calculate the amount of CO2 produced

#### After incubation and redrying of the soda lime

Weight of dish and soda lime                                                     = ____________ g

Weight of dish and soda lime after redrying (K)                         = ____________ g

Sample soda lime wt gain (L)            = K – J           = ____________ g

## MEASURING DECOMPOSITION USING SODA LIME DATA FORM 3: SAMPLES

Calculating the rate of CO2 production

1. Calculate the corrected weight gain for soda lime using:

Corrected                                 sample                          blank

soda lime                      =          soda lime                    soda lime

wt gain                                     wt gain                         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 content from Part 1, step 5 on the Measuring Decomposition Using Soda Lime Data Form 1. Soil Moisture Content):

Dry wt =          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 milligrams CO2 produced per day per kilogram of dry soil. Use your answers from the previous two steps in place of the Y and Z in this equation:

CO2 production rate = Y mg CO2 x 1.69/days incubated = _______ mg CO2/day/kg dry soil

Z kg dry soil

© NSTA. Cornell Scientific Inquiry Series.

For use with Invasion Ecology, Section 2: Invasion Ecology Protocols