Measuring Soil Microbial Activity

Measuring Soil Microbial Activity

Measuring Soil

This activity examines how soil microbes, such as bacteria and fungi, are involved in carbon cycling. Students design experiments to explore the relationship between microbial respiration rates and soil variables such as temperature, habitat, soil type, and agricultural management choices. Four methods for measuring CO2 released from soil are provided, one in the field (CO2 probe), and three in the lab (CO2 probe, bromothymol blue (BTB) and acid-base titration).

Grade Level Middle School through Undergraduate (Grades 6-16)
Subjects Biology, Physical Science, Agriculture, Environmental Studies, Microbiology
Resource Type Investigation
Concepts/Skills decomposition, respiration, carbon sequestration, climate change, microbial ecology, soils, carbon cycle, data analysis, scientific argumentation
Time Required Varies by technique and experimental design. Two to seven 50-minute class periods spread out over a one to two week period.
Prior Knowledge Familiarity with the components of experimental design, data collection and data analysis. Basic understanding of cellular respiration, carbon cycle, role of soil microbes in ecosystems, and role of CO2 as a greenhouse gas.
Required Supplies Varies depending upon activity.  See activity description for details.  Basic lab method requires either, BTB (bromothymol blue), CO2 probe or NaOH titration set-up.  Field method requires CO2 probe and  chamber constructed from 5-gal. bucket or similar vessel.
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Measuring Soil Microbial Activity V1.1 (.zip 16 MB)
Includes: Teacher Instructions and Answer Key, Student Pages, Carbon Sequestration In Soils, Soil Microbes Presentation, Types of Soil Microbes and their Functions in Ecosystems, Sample Data, BTB Presentation