Organic gardening is gardening without man-made chemicals, like synthetic fertilizers and pesticides. The goal of organic gardening is to cultivate an ecosystem that nourishes and sustains plants, soil microbes and beneficial insects. It’s also proven to be better for the environment.
It begins with improving the soil by adding compost. Compost can be made from grass, leaves, yard debris and kitchen scraps, or purchased from garden centers and mulch suppliers. Mixing compost into the soil helps it retain water and nutrients and supports beneficial microbes, which are essential to healthy plant growth.
This science experiment shows students how to build and maintain a mini-compost pile and then use the soil for planting. The experiment continues as the students observe and record the growth of bean seeds in the soil they have made.
- Large can or jar with a top
- Assorted organic waste materials (coffee grounds, fruit rinds and skins, dried leaves, grass, crushed cereal); ensure all materials are broken into very small pieces
- Bean seeds
- Styrofoam cups with 2-3 small holes punched in the bottoms
- Before starting the experiment, discuss the elements that plants need to grow - sunlight, air, water, nutrients and soil. Then, discuss the role soil plays in plant growth: it provides support as well as stores moisture and nutrients. Also, talk about the difference between healthy, well-nourished soil and poor soil which inhibit plant growth. If possible, have students do research on the benefits of organic gardening.
- Have students layer the composting materials into the jar or can. Then, have them stir the mixture and moisten it with water.
- Cover the container and punch several small holes in the top.
- Place the container in a warm location and look at the contents daily.
- Every few days, have students stir the mixture.
- When everyone agrees that the mixture has turned to soil, have students use the soil to plant bean seeds.
- For the second part of this activity, each student will grow his or her own plant. If needed, provide additional potting soil beyond what students “created,” and have students put their names on their styrofoam cups.
- Have students fill their cups about ¾ full of soil. Then, place a bean seed on top and add another ½-inch of soil and water gently.
- Place the cups in a sunny location and have students water their cups regularly to keep the soil evenly moist (not soggy) while the seeds germinate.
- Observe the cups daily. Have students keep a record of how many days to germination (sprouting), and then the growth of the bean plants.
Wrap up the experiment by discussing the outcome. How does the compost smell? How is this soil the same or different from the soil in other gardens? What do you notice about the bean plants as they grow? This experiment is a great way to demonstrate the importance of using healthy, sustainable gardening methods.
This activity was adapted from After-School Exploration: Fun, Ready-to-Use Activities for Kids Ages 5-12.