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Warm Up Exercise - Turn to your neighbor and take five minutes to answer the following question. You are allowed to use a calculator if you have one.
One morning, two old men are drinking coffee and are debating who contributed more carbon dioxide to the atmosphere during their lifetime. The first man (Fred) was a farmer and converted 50 hectares of prairie to corn fields 40 years ago (50,000 kg soil carbon per hectare), growing corn ever since while using draft horses for power. The amount of soil carbon in his fields declined by 50% during this period. The second man (Joe) was a carpenter, and drove an average of 130 kilometers round trip to work in his pickup truck 200 days per year for 40 years, getting an average of 6 kilometers per liter of gasoline. There are 0.72 kg of carbon per liter of gasoline.
Discuss the following questions with a neighbor. After each set of questions, your instructor will talk about the question set with the entire class before moving on to the next question set.
Question 1. Look at Figure 1a and make sure that you understand the X and Y axes. Next, describe the pattern displayed by the two lines.
Question 2. If carbon is lost from the agricultural soil over time, this carbon has a source (comes from somewhere) and goes somewhere (sink). Prior to cultivation, one hectare (about two football fields) of agricultural land in the Midwest could have contained more than 50,000 kg of carbon, which is equivalent to the amount of carbon in about 20,000 gallons of gasoline.
Question 3. Soil contains many different types of microorganisms such as bacteria and fungi. There is a very common microbial process in which these microorganisms use organic carbon in the soil.
Question 4.
Question 5. Cellular respiration by microorganisms results in the conversion of soil organic carbon to carbon dioxide.