Lab Experiments in Rebuilding Soil with Biochar
Copyright 2013 K.salo.85, Wikimedia Commons https://commons.wikimedia.org/wiki/File:Biochar.jpg
Students learn about soil properties and the effect biochar—charcoal used as a soil amendment—has on three soil types, sand, loam and clay. They test the soils’ water retention capability before and after the addition of biochar. During the activity, student teams prepare soil mixtures, make observations (including microscopic examinations), compare soil properties, conduct water retention tests, take and record measurements, and analyze their observations and data. They see how the physical properties of soils—color, texture, and particle size—can be indicators of nutrient content and water retention capabilities to support plant growth. From their findings, they consider biochar’s potential benefits for environmental and agricultural applications, especially in conditions of drought and depleted soils. An activity lab sheet is provided to guide experimental data collection and analysis.
Agricultural engineers design biochar soil applications as an inexpensive and effective means of improving water-holding capacity. Using biochar as a soil amendment has the potential to improve agriculture production in areas of prolonged drought, such as regions in California and Texas; however, limited studies exist in selecting different biochar to help sustain water retention levels, especially when the soil is drier than average. Using results from this activity and what they learn about biochar as an additive to alter soil properties, students determine a soil/biochar mixture that might be helpful for agricultural applications.
After this activity, students should be able to:
- Describe the significance of soil water retention.
- Compare and contrast different soil properties with the addition of biochar.
- Explain how biochar could be used for agricultural applications.
- Measure and record water retention data for different types of soil mixtures.