Agricultural Literacy Curriculum Matrix
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Types by Texture
3 - 5
1 - 1.5 hours
Students will learn about soil texture and determine the texture of several soil samples.
- Soil samples brought in by students from home, cleaned of rocks, roots, etc. (about 1 cup)
- Quart jars
- Alum (optional)
- Soil samples of sand, silt, and clay
- A Soil Sample Kit is available for purchase if local samples are not available.
- Dirt Shake handout
- Soil Texture Triangle handout
- Small bowls
Essential Files (maps, charts, pictures, or documents)
silt: soil particle that is between 0.05 and 0.002 mm.
loam: a mixture of sand, silt, and clay
clay: soil particle less than 0.002 mm.
sand: soil particle that measures between 2.00 and 0.05 mm.
Did you know? (Ag Facts)
- Almost all the food you eat and fiber used to make your clothing, and lumber to build homes is produced by soil.1
- One shovelful of soil can contain more species of living things than live in the Amazon rain forest above the ground.1
- 6 billion bacteria species can be found living in a cup of soil.1
- Farmers use conservation techniques and practices to help maintain fertile soil for planting crops.1
Background Agricultural Connections
Interest Approach – Engagement
- Start a conversation about soil with your students. Ask the following questions to build interest.
- "What forms of life does soil support?" (plants, bacteria, insects, earthworms, crops)
- "Name a function of soil that plants depend upon?" (medium for plant growth, transports nutrients & water, anchors roots)
- "Do all soils look the same, feel the same, and contain the same nutrients?" (no)
- "How do farmers find out what nutrients are missing in the soil before planting their crops?" (take soil samples and have them analyzed in a laboratory)
- "What environmental factors play a role in determining soil types?" (mineral material, time of formation, climate, landscape position, organisms)
Activity 1: Dirt Shake
- Divide the students into groups of three or four. Provide each group with a soil sample or instruct each group to use one of the samples brought from home. Two notes:
- This activity will not work with most potting soil. Soil texture is an evaluation of the mineral component of soil; potting soil is mostly organic matter.
- Remove rocks, roots, and anything else that is clearly not soil from samples and break up any large clumps before beginning.
- Provide each group with a quart jar. Instruct the students to place 2" to 4" of soil into the jar, measure the level of soil, and record the measurement as "total soil." It's important to measure and record the depth you start with so that you can accurately estimate the sand, silt, and clay fractions.
- Add water until the jar is two-thirds to three-fourths full. Add one teaspoon of alum (found on the spice aisle of most grocery stores; it does help the soil settle faster, but is not necessary). Be sure the lid is tight.
- Shake the jar vigorously until all the particles have been separated by the water, about two minutes. Set the jar down, and allow the soil to settle.
- After 1 minute, measure the amount of soil on the bottom of the jar. Record this measurement and label it as the “sand fraction.” Share the Dirt Shake and Soil Texture Triangle handouts with the students.
- Allow the sample to settle for 3 to 4 hours, then measure again and record the level. This second layer indicates the silt fraction of your soil.
- The remaining clay particles may take as long as a week to settle depending on the composition of the sample. However, you can use the measurements you already have to determine the amount of clay in the soil. Simply subtract the combined sand and silt measurements form the total soil measurement as shown below. Organic matter will float on the surface of the water. Generally it is a small component that won’t affect your measurements, but if there is a floating organic layer large enough to measure, subtract its measurement from the total soil before calculating the clay fraction and before moving on to calculate percentages.
- Total soil = 2"
- Sand fraction (first layer) = 1"
- Silt fraction (second layer) = 1/2"
- Clay fraction (total soil - sand + silt)= 1/2"
- Now convert the measurements into percentages as shown here:
- Sand percentage (sand/total soil x 100) = (1 ÷ 2) x 100 = 50%
- Silt percentage (silt/total soil x 100) = (1/2 ÷ 2) x 100 = 25%
- Clay percentage (clay/total soil x 100) = 1/2 ÷ 2) x 100 = 25%
- Once you know these percentages, use the Soil Texture Triangle handout to determine the name of the soil type.
- Discuss the following questions:
- Why do the larger particles settle out first?
- What is the stuff floating in the jar?
- How does each person's sample compare?
Activity 2: Soil Textures By Feel
- Place four soil samples of at least three different textural types (sand, silt, clay, and loamy) into four separate bowls. Samples of sand, silt, and clay can be obtained from Utah Agriculture in the Classroom (see Materials).
- Note: Samples can be reused if allowed to dry after each use. In each subsequent use, the samples can be moistened to a paste and textured as explained. To show students what the soils look like dry, use a mortar and pestle (a wooden dowel or carriage bolt and plastic bowl will work) to pulverize the sample to its original loose state.
- Share the Soil Texture Triangle handout with students. Show them that there are different names for different types of soil. It will be the task of your students to determine the texture of the supplied soil samples.
- Explain how the different soil textures feel using the information found near the end of the Background section. Tell the students that they will be determining the texture of each soil sample by feeling it. Explain that each sample is different.
- Moisten soils to the consistency of “pasty” mud. Do not get them too wet.
- Divide the class into groups of four. Invite each group, one at a time, back to the table where the soil samples are set up in the bowls on newspaper.
- Note: You may want an activity for students to do independently at their desks while waiting for their turn with the soil samples. Four soil-themed activity sheets are attached for this purpose. The teacher should try to remain with the texturing group as much as possible to guide them through the activity and answer questions.
- Each student should place about a teaspoon of the "mud" into the palm of his or her hand. Instruct students to rub the soil between their index fingers and thumbs, feeling for the presence of sand, silt, and clay. Two notes:
- Hands must be rinsed between samples to prevent the samples from being contaminated and changing the feel, which will confuse the next students who use the samples.
- To avoid a mess, cover the entire working surface with newspaper and place a bucket of water in the middle of the table for rinsing hands. Have paper towels available. As much of the sample as possible should be returned to the sample bowl before rinsing hands.
- As they continue to feel the samples, ask students to evaluate how much sand, silt, or clay is present. Students should record their analysis of the soil based on the names provided in the Soil Texture Triangle.
- After all students have felt and examined the soils, discuss their findings and tell them the actual textures of the samples.
- Discuss the following questions:
- What is the name of a soil that contains a mixture of sand, silt, and clay?
- How do sand, silt, and clay feel? How can you tell them apart? What are their similarities and differences?
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
- All soils consist of particles of sand, silt, and/or clay.
- Soil textures can be identified by touch or through a laboratory test.
- Soil texture affects the water holding capacity and nutrient content of soils.
- Farmers identify the texture of their soil and manage it according to the needs of the plants they grow.
Contact the Cooperative Extension office located in your school's district and invite an agronomist to discuss with your class the soil's nutrient requirements farmers are faced with when planting and growing crops.
For more activities demonstrating the difference in particle sizes, see the Soil Texture and Water Percolation lesson plan.
Connect this lesson to Utah Studies by showing students the 14-minute video Dust Bowl: Grantsville Utah. This short documentary includes interviews from Utah residents who experienced the Grantsville Dust Bowl in the 1930s. Yes, Utah did experience its own dust bowl, but the cause was overgrazing rather than the turn of the plow.
Suggested Companion Resources
- Make Your Own Worm Bin (Activity)
- A Handful of Dirt (Book)
- Diary of a Worm (Book)
- Dirt: The Scoop on Soil (Book)
- Jump Into Science: Dirt (Book)
- Life in a Bucket of Soil (Book)
- Soil! Get the Inside Scoop (Book)
- You Wouldn't Want to Live Without Dirt! (Book)
- Sandpaper Texturing Kit (Kit)
- Soil Painting (Kit)
- Soil Samples (Soil Texture) (Kit)
- Dirt: Secrets in the Soil (DVD) (Multimedia)
- Dust Bowl: Grantsville, Utah (Multimedia)
- Soil Science Videos (Multimedia)
- Soil, Not Dirt (Multimedia)
- SOIL Reader (Booklets & Readers)
- Dig In: Hands-On Soil Investigations (Teacher Reference)
- From the Ground Up: The Science of Soil (Website)
- Rocks and Soils (UEN Sci-ber Text for 4th Grade) (Website)
- Soil Center (Website)
- Soil Science Society of America (Website)
State Standards for Utah
Grade 4: Science Standard 3Students will understand the basic properties of rocks, the processes involved in the formation of soils, and the needs of plants provided by soil.
Objective 3Observe the basic components of soil and relate the components to plant growth. Meeting one or more of the following indicators: a) Observe and list the components of soil (i.e., minerals, rocks, air, water, living and dead organisms) and distinguish between the living, nonliving, and once living components of soil. b) Diagram or model a soil profile showing topsoil, subsoil, and bedrock, and how the layers differ in composition. c) Relate the components of soils to the growth of plants in soil (e.g., mineral nutrients, water). d) Explain how plants may help control the erosion of soil. e) Research and investigate ways to provide mineral nutrients for plants to grow without soil (e.g., grow plants in wet towels, grow plants in wet gravel, grow plants in water).
Agricultural Literacy Outcomes
Plants and Animals for Food, Fiber & Energy
- Explain how the availability of soil nutrients affects plant growth and development (T2.3-5.c)
Common Core Connections