Biochar: Measuring and Improving Soil Function
A demonstration of standing water in clay (L) versus standing water in clay with a biochar soil amendment (R).Copyright 2017 Chetan Sawhney, RET Program, Department of Earth, Environmental, and Planetary Sciences, Rice University
Students learn how to manipulate the behavior of water by using biochar—a soil amendment used to improve soil functions. As a fluid, water interacts with soil in a variety of ways. It may drain though a soil’s non-solid states, or its “pores”; lay above the soil; or move across cell membranes via osmosis. In this experiment, students solve the specific problem of standing water by researching, designing, and engineering solutions that enable water to drain faster. This activity is designed for students to explore how biochar helps soils to act as “sponges” in order to retain more water.
Measurement is a fundamental concept in science and engineering. Without the ability to measure, engineers would not be able to design and build their research experiments, much less iterate (improve) them. Not only is measurement critical in engineering, it is also important in industries in which engineering is essential such as farming, construction, and manufacturing.
In agriculture, measurements of water tend to dictate the amount of produce (such as fruits and vegetables) a piece of land can yield. Agricultural engineers and farmers design and improve upon systems to save water. In one particular instance, agricultural engineers add materials, sometimes known as amendments, to soil in order to aid in water retention. As a result, plants thrive in soils with higher concentrations of water because they are less likely to wilt and dry out. In this activity, students facilitate engineering designs and work with measurements, water, and soil to come up with designs for improved water retention.
After this activity, students should be able to:
- Describe what permits or prevents fluids (usually water) to move through pore spaces or fractures of different soil types.
- Describe how biochar can be used to facilitate hydraulic conductivity.
- Evaluate the strengths and weaknesses of different designs for testing hydraulic conductivity.