What do trees eat to grow so big?

Help youth explore how carbon that makes up carbon dioxide as a gas can become a solid plant.

Tomatoes on the vine

Have you ever wondered where trees get their mass from? One common misconception is that the mass (increasingly bigger size) of a tree comes from the soil. This misconception makes a little more sense when we realize that early on, students are often taught that plants need soil (enhanced “dirt”), water and sunlight to grow. Rarely is the plant’s need for air, a mixture of gases including carbon dioxide, clearly stated. Even later when photosynthesis is taught, the location of the carbon dioxide is not always clearly connected to air.

Youth can increase their understanding of how plants grow by planting vegetable seeds. If you grew a tomato plant in a pot starting with a tiny tomato seed, where does most of that tomato plant come from? If you weighed the dry potting soil at the beginning of the season then grew the tomato plant, harvested and ate lots of tomatoes, then weighed the dry soil at the end of the season, there would be very little difference.

Ninety percent of the dry weight of most plants is carbon and oxygen from carbon dioxide. It is weird to think that the same carbon that makes up carbon dioxide as a gas can become a solid plant.

It might be helpful to think of the process in reverse. What happens when a wood log on your campfire burns? What does it turn into? Do you think if you collected the ashes at the end of a fire, it would weigh as much as the original logs that you burned? Where does the rest of that log go? Much of it becomes carbon dioxide in the atmosphere.

Michigan State University Extension and the Michigan 4-H Youth Development program help to create a community excited about STEM (Science, Technology, Engineering, and Mathematics). 4-H STEM programming seeks to increase science literacy, introducing youth to the experiential learning process that helps them to build problem-solving, critical-thinking and decision-making skills. Youth who participate in 4-H STEM are better equipped with critical life skills necessary for future success.

To learn more about the positive impact of Michigan 4-H youth in STEM literacy programs, read our Impact Report: “Equipping Young People for Success Through Science Literacy.”

To learn more about MSU Extension, visit the MSU Extension website. To learn more about 4-H and Extension opportunities in Alcona County, stop by our Harrisville office at 320 S. State St. Harrisville, MI 48740, or visit us online at our Alcona County MSU Extension Facebook page or Alcona County Extension office page.

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