Which Soil Works Best?
- Biological Science: Plants--Soils
- Introductory Statement
Students will plant seeds in a variety of soils to see which soils provide the best medium for plant growth.
- Math Skills
- Recording data
Clear plastic 9 oz. tumblers
School yard "dirt"
Large bean seeds
- Key Question
Which soils are good for growing plants?
- Background Information
Soils provide the water and mineral that a plant needs. Without soil, the plant can be watered, but it becomes difficult to give the plant the nutrients that it gains from the soil. Soil also provides support for the plant and its root system.
Soil usually has three separate layers. The top layer contains minerals and humus, the decayed remains of animals and plants. Humus and minerals are needed by plants for good growth. The second layer contains humus and minerals that have been leached from the top soil. The third layer consists of rocks that are being broken down to form soil.
A great helpmate to the enrichment of soils is the earthworm. Earthworms burrow through the soil and leave castings of digested leaves and other matter which help enrich the soil. They also improve the soil with their tunneling by making it easier for air and water to soak in. Earthworms do not make poor soil into good soil, but rather they keep the soil in good condition for growing.
- Management Suggestions
- Students may wish to work in pairs or teams of three or four to plant and observe four sets of seeds
- Teamwork also makes it appropriate for "jobs" to be assigned. They may all wish to keep a daily log of activity and then compare notes.
- Use four clean clear cups per team. Fill each one three-fourths full with different types of soil: potting soil, sand, playground "dirt" and clay. Plant a bean seed in each cup, placing the seed up against the clear side wall of the cup for easy viewing. Add measured amount of water to each cup and record.
- Predict and record what you think will happen in each cup.
- Allow time for seeds to grow. Illustrate the results.
- Compare results and discuss. Draw conclusions regarding best medium for growth.
- How are all the types of soil alike? How are they different?
- Why do you think one might be better than another for growing bean plants?
- Discuss the difference between germination and actual plant growth.
- How shall we decide which seed grew the best? Which kinds of things do we look for? size of plant? color? number of leaves?
- Does more than one kind of soil produce a good plant?
- Could soils be combined to make a better growing bed?
- Can plants grow without soil? How?
- Create a new soil mix and test it.
- Write a poem or a story about seeds and soils.
- Use adjectives to describe soil: rough, sandy, earthy, etc.
- Write a soil poem.
Which soil works best?
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