Monitoring Soil Carbon in Warren County

This summer we are beginning a long-term soil carbon monitoring study to measure indicators of soil quality in Warren County. Soil carbon monitoring is the act of measuring the organic carbon content in a particular plot of soil. So far this summer, we have performed soil carbon monitoring at two different farm locations –one in Waynesville and another in Clarksville.

The first step in this monitoring effort is site selection on the farm. By mapping a monitoring transect, or a straight line across the surface of the Earth, we can ensure that the tests we performed are repeatable in the future. For example, we identified one of our transects by selecting two towers as the end-points. Each test is then performed along the transect.

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Our first observations performed were the infiltration tests. We set up three different infiltration rings, evenly spaced apart from one another, and drove each ring about half way down into the ground. By adding an inch of water to each ring, we would observe and time how quickly the water would infiltrate into the ground. This test ultimately showed us how the soil in that particular area accepts the water, which reflects soil structure.

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Next, we performed a test that involves an observational hoop. A wire hoop is placed on the ground to look at vegetation density, amount of bare ground, and what types of insects inhabit the area. These factors tell us about the health and functionality of pastures, fields, and any other landscapes on which they are identified.

After placing the observation hoop, we identified a grid to take our soil samples from. Samples are then taken at eight sampling points using a soil sampling probe that extracts soil cores. We then separated the cores by top, middle, and lower layers.

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​The last assessment we performed was the soil density test. This tells us porosity, which is a measure of spaces in the soil. It also helps us measure the total carbon that is in the soil. This test is performed by digging a hole and using a bulk density core sampler to extract the soil from the desired layer we measure. Once the samples were completed, they were delivered to the laboratory for analysis. 

​The monitoring effort will be repeated at the same locations in 2020. For more information on soil carbon monitoring visit: http://soilcarboncoalition.org/

​By: Brennan Woodall and Emilie Fisher, Warren Co. SWCD Summer Interns

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