Edition 3 (2016) GOAL STATEMENT: Students will learn about soil as a natural resource, what its components are, how it is used, and whether it is renewable. OBJECTIVES: Students will collect, graph, and analyze data. Students will explain how weathering creates soil. Students will explain what soil is used for and if it is renewable. REQUIRED MATERIALS Two rocks that will chip or create a powder when rubbed together Photos of extreme soil types Containers with different soil components (sand, clay, organic matter, etc.) Copies of It s Not Just Dirt! 4-page worksheet packet (1 per student) Plastic jars with screw-on lids, pint size or larger (1 per group) Small shovels (1 per group) Small white labels Water Protractors (1 per student) Metric rulers (1 per student) Colored pencils AMOUNT OF TIME TO ALLOW: 90 minutes. It takes several hours for the soil layers to settle completely, but the lesson can be completed without waiting for this to occur. You may consider splitting the lesson into two class periods if you wish for the soil layers to settle completely. Extension activities will take additional time.
Soil is a natural resource, just like air and water, and it s a very important one! Soil is the place where all terrestrial life begins. Most people consider soil to be just dirt, but it s much more than that. Soil is more than just a collection of particles. It is a complex body, an ecosystem all its own, and a dynamic substance that is constantly changing and reacting. Soil is considered a three-phase ecosystem because it contains solid, liquid, and gas phases. About 50 percent of the soil is solid particles both inorganic (or mineral) particles and organic matter. The inorganic particles of a soil are classified by size. The largest particles are called sand, the smallest particles are called clay, and the intermediate-sized particles are called silt. The specific combination of sand, silt, and clay particles in a soil determines that soil s texture. The other component of soil solids the organic matter is comprised of three parts: the biomass, residues and byproducts, and humus. The biomass consists of all living creatures in the soil from organisms as small as bacteria to those as large as insects, plant roots, and even mammals like groundhogs. The biomass functions to create biopores, or channels within the soil, and serve important roles in nutrient cycling. Residues and byproducts provide nutrients to the biomass and provide substances that promote soil aggregation or clumping. The last component of organic matter, called humus, is the stable end product of decomposition. Humus does not provide the soil with nutrients, but it does contribute to the soil s ability to retain or store nutrients. Just as there are many different types of trees and flowers, there are many different types of soil. Some soil types are better suited to farming than others. Farmers are limited to using the land, and thus the soils, that they own. The amount of a crop that can be produced in a certain field is limited by the ability of the soil to grow that crop. Soil types cannot be changed, but the ability of a soil to produce a crop can be improved. Farmers often add amendments such as lime and fertilizer to help their crops grow better. 15 minutes How is soil created? To show how rocks and minerals become part of soil, take two rocks and rub them together over a piece of white paper. Explain that this simulates weathering, or the various mechanical and chemical processes that cause exposed rock to decompose. Show the students the resulting powder or chips. Alternatively, you can pour water over the rocks and collect it to show the sediment that is worn away by rain. Explain that sediment will eventually become part of soil. Animal and plant matter that decays over time also contributes to the formation of soil. Different combinations of these elements determine soil type. Show the students pictures of various extreme soil types: desert, clay, and fertile farming soil. If possible, show examples of soil components (such as sand, clay, organic matter, etc). Lead a short discussion of the ways soils are used in agriculture. Ask students to consider what characteristics would make one type of soil better for growing crops than another.
60 minutes Divide students into small groups, and provide each group with a jar and small shovel. Take students outside and have each group collect a soil sample. Each group should obtain their sample from a different area of the school yard such as under trees, from the playground or ball field, from a garden, and beside a pond or stream. Students should place about one cup of soil in their jar. Have students label the jar based on where the sample came from. Alternatively, you may collect all of the soil samples before conducting the lesson. Once each group has a soil sample, follow these instructions to complete the activity. 1. Ask students to visually observe their samples and record their thoughts on their worksheets. They may take note of what they think the sample is mostly made of, its color, how much air is in it, how dense it is, etc. 2. Have students add clean water to their samples until the jars are about three-quarters full. Ask students to observe what happens as they add the water. Have students screw the lids on their jars. 3. Have students shake their jars well. Then have them set the jars on a level surface and leave them alone for several minutes until the soil has settled. Note that the sand and silt will settle after just a few minutes, but the water will remain murky until the clay settles out. It will take serveal hours for the clay to settle fully and for the layer of clay to be visible. If you choose to complete the lesson before the clay settles, explain how students should amend their data collection and pie chart to reflect this. 4. After the mixture has settled, ask students to describe what happened. Make sure students understand what they are seeing in the jar. Sand is the heaviest particle and will form the bottom layer. Silt particles are lighter than sand and will form a layer above the sand. Clay is the lightest particle. It will stay suspended in the water for several hours. Once it settles out, clay will form a very thin layer on the top of the soil column. Water will be visible above the soil column. (Students may measure the height of the water, but this measurement will not be used in the pie chart because the water is not part of the soil.) Organic matter will float on top of the water. 5. Have students measure each layer and record the results on their worksheets. 6. Have students use their recorded values to create a pie chart of their soil. You may need to provide guidance about how to convert their measurements into the angles in the pie chart and how to draw the pie chart. After the lesson, the soil and water may be dumped outside. Remove as much soil from the jars as possible before washing them in a sink. Soil should not be washed out in a sink because it will clog the drain.
15 minutes Allow students to answer the analysis/conclusion questions within their groups. Use these questions to guide a class discussion about the similarities and differences between soils. Why might samples from different areas have different characteristics? For example, soils from paths that are frequently walked on could be very dense, and garden soil could be full of organic matter. Sandy soils don t hold water well; clay soil doesn t allow oxygen in as easily. Which soils might be best for growing plants, and why? Talk about soil as a resource. How is it used? Is it renewable or nonrenewable? Renewable resources can be replenished through natural processes. Nonrenewable resources cannot be produced, grown, generated, or used on a scale that can sustain its consumption rate. Most scientists classify soil as a nonrenewable resource because it takes a very long time to create soil. Use an apple to simulate how much of planet Earth is covered in soil and how much of that soil can be used by humans to grow food. Instructions for the demonstration are available from Indiana University Purdue University of Indianapolis; visit the website at <www.iupui.edu> and search for Earth: the Apple of Our Eye. There are also many videos and animations showing this simulation; conduct an Internet search for apple as planet Earth. Have students determine the texture of their soil by feel. USDA s Natural Resource Conservation Service (NRCS) provides a flow chart to follow. Visit the website at <www.usda.gov> and search for guide to texture by feel. Try growing seeds in each soil type and find out if differences in the soils affect growth and development. Research what type of soils different plants like. Find out what type of soils are around the school or students homes by using the USDA Web Soil Survey. Visit the website at <www.websoilsurvey.nrcs.usda.gov> and click the green button. Find a location using the address, then use the AOI (area of interest) tool to draw a box around the area you want to explore. The Web Soil Survey program is challenging to use for those not familiar with the program; it is recommended that the teacher try it before class and complete the survey on a projector with the class. Watershed Technician This person is a specialist trained in conserving, enhancing, and protecting watersheds and stream drainage basins. He or she studies the contours of a given area of land and, using scientific instruments, determine how water flows through and beneath that section of land. A watershed technician also works with ecologists in planning water retention features such as ponds, streams, and drainage fields to minimize the impact on the ecology of the area.
Environmental Technician This person monitors the environment and investigates sources of pollution by performing laboratory and field tests. Soil Conservationist This person plans and assists with the execution of projects that help conserve soil. Soil conservationists work with farmers and landowners to fix environmental problems by implementing conservation practices. County Agriculture Agent This person provides leadership in determining, implementing, and evaluating educational programs which are designed to help farmers and other people in the agricultural industry succeed. The agent is an educator, information provider, needs assessor, and problem-solving resource for clientele. Crop Consultant This person helps farmers make management decisions by providing technical advice on many topics related to growing crops. Crop consultants scout fields for diseases and insects during the growing season and provide farmers with information and recommendations regarding the need for treatment. They may collect soil samples in order to provide recommendations on the application of fertilizers. Consultants also provide irrigation advice and are becoming more proficient in the emerging area of precision farming. Conservation Planner This person works with land owners to create a plan that outlines conservation practices and systems they use to develop and maintain their properties. The plan involves all of the natural resources (soil, water, air, plant, and animal resources) on the property. Student understanding can be evaluated through class discussion or assessment of completed activity data sheets. The following questions may also be used to evaluate student learning. 1. Where does soil come from? (How is it made?) 2. What is soil made of? 3. Describe the similarities and differences you observed between the soils used in the experiment. 4. Why is soil important? United States Department of Agriculture, Natural Resource Conservation Service, <www.nrcs.usda.gov>. What is Soil? Soil-net.com. <www.soil-net.com/legacy/schools/what_is_soil1.htm> Dr. Dirt K-12 Teaching Resource website, <www.doctordirt.org>. Soil Profile. ThinkQuest website, <library.thinkquest.org/j003195f/newpage5.htm>.
Soil Jar Activity Instructions Name: Date: Period: Goal Observe the different components of soil and compare and contrast different types of soil. Materials small shovel clear jar with lid soil sample water metric ruler protractor colored pencils Background We often think of soil as one thing, but it is actually made up of many parts, including sand, silt, clay, organic matter, water, and animals that live in soil. The amount and concentration of these elements combine in many different ways to give us many different soil types. Some soil types are better than other for growing plants. Directions 1. Get into your lab group. 2. Listen carefully as the teacher explains the activity. 3. Using your shovel, collect a sample of soil. Fill your jar a third of the way with soil. 4. Label your jar with the place where you collected the soil. 5. Observe your soil. Write down your observations in the space provided on your worksheet. 6. Add water to your soil until the jar is about three-quarters full. Observe what happens as you add the water. 7. Screw the lid on the jar tightly. Shake well until the water and soil are combined. 8. Set the jar on your desk and wait. Observe what happens as the soil settles to the bottom of the jar. 9. After the sample has settled, use a ruler to measure (in mm) each layer. Record the measurements on the table provided on your worksheet. Sand is the heaviest particle and will form the bottom layer. Silt particles are lighter than sand and will form a layer above the sand. Clay is the lightest particle. It will stay suspended in the water for several hours. Once it settles, clay will form a very thin layer on the top of the soil column. Water will be visible above the soil column. You will not measure the water because it is not part of the soil. Organic matter will float on top of the water. 10. Use your data to make a pie graph showing the proportions of each of the components in the soil sample. Follow the instructions on the next page to make your pie graph. because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry,
Soil Jar Recording Sheet Name: Date: Period: 1. Observe your soil, and record your observations here. You may want to include details about color, smell, density, what s in it, etc. 2. Measure the height of each layer (in mm). Record your measurements in the Height of Layer column below. Soil Component Height of Layer Percentage of Height Angle in Pie Graph Sand Silt Clay Organic Matter Total Height: 3. Find the sum of the heights you measured for sand, silt, clay, and organic matter. Record the value. 4. Find the percentage of the whole represented by sand. To do this, divide the value you recorded in the Height of Layer box for sand by the Total Height. Your answer should be in the form of a decimal. Record this value in the Percentage of Height box in the sand row. Repeat this procedure for silt, clay, and organic matter. 5. Check your work. If you have calculated correctly, the values in the Percentage of Height column will add up to 1. 6. Find the angle of the sand section you will draw in your pie chart. Multiply the decimal value you recorded in the Percentage of Height box for sand by 360 (the number of degrees in a circle). Record this value in the Angle in Pie Graph box in the sand row. Repeat this procedure for silt, clay, and organic matter. 7. Check your work. If you have calculated correctly, the values in the Angle in Pie Graph column will add up to 360. 8. Draw your pie chart. Start by drawing the radius of the circle (a straight line connecting the center to the outside). Then draw each division. Lay the bottom edge of your protractor against the radius. Measure the angle for the sand section, make a mark on the edge of the circle, remove your protractor, and draw a straight line connecting the mark to the center of the circle. Repeat this procedure to draw the sections for silt, clay, and organic matter. 9. Color each section a different color to match your key. because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry,
Name: Soil Pie Graph Date: Pie Chart Color Key Period: Sand Silt Clay Organic matter Describe the difference between your soil sample and others from your class. Which do you think would be the best for growing crops and why? because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry,
Conclusion Questions Name: Date: Period: Weathering creates soil particles from rocks over time. Explain the process of weathering. Soil is made up of several different things. What are the major components that make up soil? Explain what other human activities can use up soil other than agriculture. Soil is a natural resource. Explain how this natural resource is used up over time. because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry,