SOIL TEMPERATURES. Introduction. Time Needed. What You Need. Safety Precautions

Transcription

1 SOIL TEMPERATURES Introduction The temperature of soil is determined by factors such as season, soil type, moisture content, and weather conditions. Depth also affects soil temperature, since a layer of soil acts an insulator to the outside weather conditions. Temperature is critically important to soil-dwelling organisms. In plants, temperature affects budding, growth rate, and length of growing season. Temperature also determines whether moisture in the soil is in the form of water or ice. In this experiment, you will collect data on soil temperature over a period of a month. You will use your data to predict future soil temperatures. Time Needed 50 minutes on day 1 15 minutes on follow-up days (3 times a week for 4 weeks) What You Need 3 soil thermometers 3 rulers stopwatch small hand shovel masking tape graph paper science notebook Safety Precautions Take care to avoid breaking the thermometer when pushing it into the soil and when removing it. Please review and follow the safety guidelines.

2 SOIL TEMPERATURES 2 What You Do 1. Follow your teacher to an outdoor area. You will work in a group of three students to monitor soil temperatures in this area. 2. Clear the area s surface of leaves and other debris. 3. Use the shovel to loosen the soil in a large enough area to accommodate three soil thermometers. 4. Examine the loosened soil and describe it in your science notebook. Include information about the soil s color, texture (smooth, slightly gritty, or very gritty), and amount of moisture. Also describe the weather conditions at the site. 5. Tape each of the three thermometers to a ruler so that the bulb is at the 0 on the ruler (Figure 1). Label the three rulers and thermometers as A, B, and C. ruler 3 tape 2 1 soil thermometer bulb at zero 0 Figure 1 6. Simultaneously push all three rulers and thermometers into the soil and leave them in place for exactly 5 minutes. To do so: a. Gently push ruler and thermometer A into the soil so that the 2-inch (in., 5-centimeter [cm]) mark on the ruler is even with the soil surface. b. Gently push ruler and thermometer B into the soil so that the 3.9-in. (10 cm) mark on the ruler is even with the soil surface. c. Gently push ruler and thermometer C into the soil so that the 5.9-in. (15 cm) mark on the ruler is even with the soil surface.

3 SOIL TEMPERATURES 3 7. Remove each thermometer at the same time and record the temperatures in your science notebook. Write the date beside these 3 temperature readings. 8. Repeat steps 1 through 7 three times a week for 1 month. 9. Find the average temperature of each site. To do so, add the temperatures collected at each depth then divide the sum by the number of temperatures. Observations 1. Which depth showed the highest average temperature? Which depth showed the lowest average temperature? 2. Prepare a graph of temperatures against soil depth. Write a statement that sums up the information in each graph. 3. Which depth showed the greatest changes over the month? What factors do you think contributed to this? 4. Which depth showed the least changes over the month? What factors do you think contributed to this? 5. How do you think your findings in this experiment might be different in other seasons? Want to Know More? See Our Findings.

4 SAFETY PRECAUTIONS Review Before Starting Any Experiment GENERAL Always obtain your teacher s permission for experiments performed at school, and your parent s permission for experiments performed at home, before attempting any experiment. Read all instructions for an experiment before starting the experiment, and follow the directions exactly as they appear in this volume. If an experiment requires adult supervision, do not perform the experiment unless you have an adult supervising you the entire time you are performing the experiment. Wash your hands before the start of and after each experiment you perform. Keep your work area clean. Never eat or drink while performing an experiment. Never taste a substance used in an experiment unless you are told that it is safe to do so. Be aware of the location of safety equipment you may need in an emergency, such as running water, an eyewash if you are at school, and a fire extinguisher. If you are going outside, make sure you have permission to go from your teacher and parent. Take a buddy with you, and dress appropriately for the weather. Make sure you or someone who accompanies you is familiar with the area, and bring along a firstaid kit in case of emergency. Never look directly into the Sun. CHEMICAL SAFETY Always wear goggles when working with chemicals, such as acids and bases, and near heat sources like flames. If at all possible, avoid wearing contact lenses when working with chemicals. If any substance gets into your eyes, notify an adult (e.g., your teacher or parent) immediately, and flush your eyes with running

5 SAFETY PRECAUTIONS 2 water for at least 15 minutes. Do not mix chemicals unless you are told to do so by a teacher or parent. Never touch, taste, or smell chemicals unless instructed to do so. Keep chemicals in closed containers when they are not in use. Dispose of all chemicals properly. Do not pour any chemicals or solids down the drain unless instructed to do so. Use safety gloves and a plastic apron when handling chemicals. If any chemicals spill on your skin, rinse the affected area with running water for at least 10 minutes, and notify your teacher or parent immediately. Take precautions to avoid spilling chemicals. If a chemical spills on any surface, notify your teacher or parent immediately to assist with clean-up. Exercise caution when using sharp instruments such as knives or scissors. Always cut away from yourself, not toward yourself. If you cut yourself, notify your teacher or parent immediately. GLASSWARE Clean glassware when you are finished with the experiment. Be careful when using glassware. If a piece of glassware breaks, have an adult assist you in clean-up to avoid injuries from broken glass. Never use broken or damaged glassware. FIRE SAFETY Do not heat glassware that is not completely dry. Do not pick up hot glassware without heat-resistant gloves or tongs. When heating glassware, keep it away from yourself and from others. Do not heat anything unless instructed to do so by a teacher or parent. Do not heat substances in a closed container. After an experiment, make sure that all heating sources are off and that all flames have been put out.

6 SAFETY PRECAUTIONS 3 Do not reach across such heating sources as flames. If you have long hair, tie it back, out of the way. Do not wear clothing with loose sleeves, scarves, bows, ties, or anything else that may hang into a fire. Do not wear long earrings. ELECTRICAL SAFETY Do not touch electrical equipment when your hands are wet. Do not plug several electrical devices into one outlet or use an extension cord.