Colorado Agriscience Curriculum
Section: Unit: Lesson Number: Lesson Title: Plant & Soil Science Soils PS U6 L9 Soil Erosion
Colorado Agricultural Education Standards: Ag. II 10.9: The student will demonstrate an understanding of soil fertility and its effect on crop production. Colorado Science Standards: 4.15 Analyze the costs, benefits, and consequences of natural resource exploration, development, and consumption. Student Learning Objectives (Enablers) As a result of this lesson, the student will: 1. List the effects of wind and water erosion. 2. Describe how wind and water erosion occurs. 3. Identify the types of erosion.
Time: Instruction time for this lesson: 50 minutes. Resources: Plaster, Edward J., Soil Science and Management, Delmar Publishing, Albany, NY, 1985 http://www.weru.ksu.edu/new_weru/multimedia/multimedia.html Tools, Equipment, and Supplies Overhead projector or computer with projector PowerPoint: PS U6 L9 Instructor PowerPoint 1 copy per student of PS U6 L9 Job Sheet (if desired) 1 copy per student of PS U6 L9 Student Evaluation Student Notebooks Writing tools 2 old cake pans filled with two types of soil, sand and clay 1 object that weighs 1 lb Eyedropper filled with water
Key Terms: The following terms are presented in this lesson and appear in bold italics: Splash erosion Ephemeral erosion Sheet erosion Gully erosion Rill erosion Interest Approach Use current interest approach by comparing current dust storms to the dust storm of the 1930’s. Give the students 1 minute to list all the causes of the 1930’s dustbowl on one side of a piece of paper and on the other side have them write down all the good things that came out of the dustbowl. Take examples and share with each other at the end of the minute. Do dust storms occur now? After discussion show slides Slide #2-3 Read this description. These photographs were taken by: John G, Coumerilh Bird City (Cheyenne County), Kansas Saturday, 29 May, 2004 "My anemometer is located only 9 feet off the ground and between windbreaks and registered in the 50-60 mph range but neighbors clocked 80-90 mph straightlined winds. It was an unbelievable storm. It reminded me of some hurricane videos I've seen. The roar grew until our house shook. The south side of the barn (far side in this view) was blown off its foundation. This storm caused the death of a Kansas State Senator and one other person." Slide #4-8 Read this description. These photographs were taken by: Robert Grace Grace Flying Service, Inc. St. Francis, KS Saturday, 29 May, 2004 Slide #9-13 Read this description. These photographs taken by: Fred Farrell 3 June, 2005 "My impression of the storm was curiosity at first. I watched it grow from what looked like a good size brush fire but within about a minute or two it turned into this monster storm. At first I thought I could step on the gas and beat it before it crossed highway 17 but realized after a short distance that it was moving much faster than me and was too far ahead. As I approached the wall cloud I thought.... this is going to be interesting. The storm blew the car around pretty good, visibility was almost zero at times. It was the most intense between Hooper and Moffat, 2
Colorado which is a 16 mile stretch of highway." Slide #14-18 Read this description. These photographs were taken by: Gunnery Sgt. Shannon Arledge and unknown others 26 April, 2005 "A dust storm similar to special effects on the big screen bellowed across the western desert of Iraq on April 26. The storm was spawned near the border of Syria and Jordan. Weather forecasters here described the dust storm as a downburst. The ensuing storm increased energy as the winds pushed over the desert, which created a wall of dirt. Weather officials said that a downburst this strong is extremely rare for this region of Iraq. As the storm moved closer the sky changed to a shade of orange until total darkness blanketed the ground. The storm passed over in about 45 minutes, leaving a heavy sheet of dust in its wake. Forecaster say the wall of dust may have reached 4,000 to 5,000 feet, based on the height of the clouds above it." - Unknown Now that we have looked at some modern day dust storms, let’s think back to the Dust Bowl of the 1930’s. Slide #19 When I say DUST, I want you to take a piece of paper, draw a line down the center, and on the left side, write down as many things as you can to tell me about the dustbowl of the 1930’s. Then on the right side, write down as many good things that have come about as a result of the dustbowl, you have one minute, ready “DUST.” Now that you are finished, let’s take some of your examples. Review some ideas as a class. Good job, what we learned most from the dustbowl is that erosion is a devastating phenomenon that still occurs today. We will investigate why it still happens and what we can do about it. Summary of Content and Teaching Strategies Utilize PS U6 L9 PowerPoint for students to take notes. A job sheet has been included at the end of this lesson if so desired Objective 1. List the effects of wind and water erosion.
Ask the students some probing questions to lead into the objective. We are going to play higher and lower. If you make a guess I will tell you if you need to guess higher or lower to get the number I want. How many pounds make up a ton? 2,000 you are right, knowing that - how many tons of soil are lost each year due to erosion? Take a few responses, using the higher and lower game. Slide #20 Each year almost 5 Billion tons of soil is either washed or blown from farmland in the United 3
States. Of that 3.5 billion tons is due to water erosion and the remaining is due to wind erosion. Do you think this number is bad? What about soil formation—is it forming all of the time? Slide # 21 On average scientists expect to lose about 5 tons of soil per acre every year due to erosion. The water erosion alone makes up for about 4.8 tons of loss each year. When wind erosion numbers (3.3 tons per acre) are added to that, US farmland is losing about 8.1 tons per acre of soil each year. Knowing this, do you think that soil erosion is problem? You bet it is. What are some lasting effects of erosion? When I say ERODE I want you to take 1 minute and list on a piece of paper all of the effects erosion might have. Be specific, ready ERODE!! Who would like to share some of their ideas? Take some responses. You all have great ideas! Slide #22 Some lasting effects of soil erosion are: Loss of topsoil—loss of productive organisms Organic matter is gone along with valuable nutrients N-P-K Reduced root zone which reduces water holding capacity Gullies make farming and tillage operations more difficult Eroded soil pollutes lakes, streams causing harm to water populations Sediment from erosion fills up lakes, streams and waterways Huge economic losses due to un-productive soil Use the Hieroglyphic Moment to have students understand the effects of soil erosion Objective 2. Describe how wind and water erosion occur.
Fill two old cake pans full of different soils, one more clayey and one more sandy. Ask the students which one do they think would be more susceptible to water erosion, after taking the guesses, ask them what could you change to either increase or decrease erosion in these two pans. With one lying flat, pour water across it. With the other tilted pour water across it. Again ask for input. The point is there are many variables which cause water erosion to occur, only one variable, such as soil type can’t be the only thing looked at. I have up here two cake pans with soil in it, one is pretty sandy, and one is pretty clayey. Which one do you all think is more prone to water erosion? What if I tip one up and leave one flat, then which one is going to erode faster? Let’s give your theories a test. I am going to pour water across this flat sandy one, and then tip up the clay one and run water across it. As you can see, I changed some variables and could alter the erosion amounts. What variables could there be to cause water erosion? List some on your paper and then we will compare our answers. 4
Wait for the students to write their responses. There are five variables that affect water and wind erosion for soils they are: Slide #23 Texture and structure The coarser the texture, the higher the infiltration rate, the lower the risk of water runoff Fine particles are detached easier then large particles, therefore silt erodes quicker then sand Good structures also resist rain splash and take in water to reduce run-off Slide #24 Slope Two components of slope must be considered Length and steepness or grade Length allows for volume while grade allows for water velocity With wind erosion, the longer the field the more piled up the soil would be at the end of the field, wind has a snowballing effect on soil Slide #25 Surface Roughness Rough soil slows water and reduces downhill flow and also acts as a windbreak Therefore tillage ridges are helpful Tillage across slopes helps slow water and wind erosion while tillage with the slope promotes downhill water erosion Slide #26 Surface Cover Surface cover reduces water impact from falling water and also slows surface movement of water Surface crops hold soil with their roots and combat surface flow Row crops are effective when the canopy covers the exposed soil Slide #27 5
Climate Dry soils and dry climates promote wind erosion, the drier the soil the more likely it will be picked up transported elsewhere. Follow this objective with the Cartographer Moment asking the students to create a map in their notes that shows each of the factors in action for deeper understanding. Objective 3. Identify the types of erosion
Show the students the 1 lb weight and ask them questions about how much soil an object like that could displace if you dropped it and then compare it to a raindrop by using the eyedropper. I have up here a 1 pound weight and an eyedropper with one raindrop in it. Which one do you think would displace the most soil if I dropped the weight and the raindrop on some soil? If I drop them both from the same height, the weight would displace more, but how high up does a raindrop come from? A two inch per hour rain, has the same energy as a one pound weight dropped from 47 feet onto one square feet of soil. Falling rain has great power! We have talked extensively about wind and water erosion but what are the types of erosion? They types of erosion are based on the severity of erosion. Slide #28 Splash erosion A water drop hits the soil and moves particles as much as 5 feet from the point of impact. Slide #29 Sheet erosion A thin layer of soil is removed in a sheet. This problem is hidden until all topsoil is removed. Slide #30 Rill erosion Many small channels on slope, running water carves out rills, small enough to be filled in by tillage. Slide #31 Ephemeral erosion Large rills, tillage can cross it but won’t fill it in completely. The next rain will cause even greater damage.
Slide #32 Gully erosion So large that equipment cannot cross it. Begin on steep slopes where water has the power to cut large channels.
Review/Summary Who thinks they can name 3 of the 5 types of erosion without looking at their notes? Take a volunteer very quickly. Let several give it a try and then use a form of the choral response moment until the whole class has all five types down. Application Extended classroom activity: Invite a soil conservationist from the local USDA Natural Resource Conservation Service to come to the classroom and perform a soil erosion demonstration or to talk about the conservation changes the USDA has implemented in the last 60 years. FFA activity: Encourage students to participate in the Land Classification CDE or the chapter could do an erosion study on a local area that needs landscaped. SAE activity: Implementing conservation practices into existing SAE’s is always prudent. Also, a student could do an agriscience project on various wind and water erosion projects.
PS U6 L9 Student Evaluation
Soil Erosion Evaluation Name_______________________________________________DATE_____________ Circle the best answer for each question. 1. Approximately how pounds of soil are eroded each year? A. B. C. D. 2. 50 million pounds 50 million tons 50 billion pounds 50 billion tons
Which element historically causes more erosion? A. Wind B. Water
What level of soil loss is acceptable per acre per year? A. B. C. D. 1 ton per acre 3 tons per acre 5 tons per acre 10 tons per acre
When topsoil is lost the following is also lost A. Organic matter B. Water holding capacity C. Profits D. All the above E. None of the above Soil erosion affects A. The field it is on B. Nearby lakes and waterways C. Tillage operations D. All the above E. None of the above What statement about texture is most accurate? A. High infiltration rates are desired B. Fine soils resist erosion C. Good soil do not resist rain splash D. Sand erodes faster than silt
What two elements of slope should be considered in regards to erosion A. Length and width B. Grade and width C. Length and texture D. Length and Grade Tillage used to control erosion should be performed A. With the slope B. Diagonal to the slope C. Across the slope D. Making very shallow ridges Using surface cover to control erosion is also important. Which statement is most true? A. Row crops are effective all the time B. Surface or low growing crops help buy holding soil with their roots C. Bare surfaces are most desired D. Surface cover increases water impact on the soil The weather factor that promotes wind erosion the most is? A. Tropical storms B. Drought C. Snow D. Rain Which type of erosion causes the least amount of erosion? A. Sheet B. Rill C. Gully D. Splash Which type of erosion is a series of large rills? A. Ephemeral B. Sheet C. Gully D. Rill Gully erosion is A. Easily fixed B. Crossed by tillage equipment C. Impassable D. Begins on gentle slopes A large concern of sheet erosion is A. It occurs only on severe slopes B. It is hidden until all topsoil is removed C. It creates huge gaps in a field D. It moves soil particles 5 feet away from the point of impact 9
Answers to the evaluation. 1. Approximately how pounds of soil are eroded each year? i. ii. iii. iv. 50 million pounds 50 million tons 50 billion pounds 50 billion tons
2. Which element historically causes more erosion? i. Wind ii. Water
3. What level of soil loss is acceptable per acre per year? i. ii. iii. iv. 1 ton per acre 3 tons per acre 5 tons per acre 10 tons per acre
4. When topsoil is lost the following is also lost i. Organic matter ii. Water holding capacity iii. Profits iv. All the above v. None of the above 5. Soil erosion affects i. The field it is on ii. Nearby lakes and waterways iii. Tillage operations iv. All the above v. None of the above 6. What statement about texture is most accurate? i. High infiltration rates are desired ii. Fine soils resist erosion iii. Good soil do not resist rain splash iv. Sand erodes faster than silt 7. What two elements of slope should be considered in regards to erosion i. Length and width ii. Grade and width iii. Length and texture iv. Length and Grade 10
8. Tillage used to control erosion should be performed i. With the slope ii. Diagonal to the slope iii. Across the slope iv. Making very shallow ridges 9. Using surface cover to control erosion is also important. Which statement is most true? i. Row crops are effective all the time ii. Surface or low growing crops help by holding soil with their roots iii. Bare surfaces are most desired iv. Surface cover increases water impact on the soil 10. The weather factor that promotes wind erosion the most is? i. Tropical storms ii. Drought iii. Snow iv. Rain 11. Which type of erosion causes the least amount of erosion? i. Sheet ii. Rill iii. Gully iv. Splash 12. Which type of erosion is a series of large rills? i. Ephemeral ii. Sheet iii. Gully iv. Rill 13. Gully erosion can be i. Easily fixed ii. Crossed by tillage equipment iii. Is impassable iv. Begins on gentle slopes 14. A large concern of sheet erosion is i. It occurs only on severe slopes ii. It is hidden until all topsoil is removed iii. It creates huge gaps in a field iv. It moves soil particles 5 feet away from the point of impact
PS U6 L9 Job Sheet
Enterprise: Soils Job: Soil Erosion
1. How much soil is lost each year to wind and water erosion? 2. What is the average loss per acre? 3. What are some of the lasting effects of soil erosion? 4. What factors affect soil erosion? 5. What are the five types of erosion (list & explain)?