Water Quality - Nutrient Management and Cropping Systems - Lesson 2 Soil Conservation

Water Quality - Nutrient Management and Cropping Systems - Lesson 2 Soil Conservation

Target Grade Level / Age Range:   

High School

Time:

120 minutes (3 class periods)

Purpose:

Students will learn about operational and structural conservation practices, and will understand their pros and cons in modern agricultural systems.

Materials:

Vocabulary (with definitions)

  • Operational – conservation practice is a short-run practice than can be implemented on a year-by-year basis.
  • Structural– long-run practice that will be in place once it is implemented until it is removed or altered.
  • Conservation--the practice of protecting natural resources against harm and waste.
  • Gully Erosion--Loss of soil in large, often impassible trenches or ditches resulting from runoff. Channels are deeper than 30 cm and cannot be removed by normal cultivation.
  • Rill Erosion- -Loss of soil in small but visible tracks that are less than 20 cm deep that can be removed by normal cultivation. Develop when surface water concentrates in depressions or low points.
  • Sheet Erosion-- Gradual removal of soil in thin layers by raindrop impact and shallow surface flow.  Results in loss of the finest soil particles.
  • Wind Erosion--Soil loss resulting from the action of the wind.
  • Watershed- - The area of land that water flows across or underground on its way to the same stream or river.
  • Water Cycle-- Transports water between earth’s land, atmosphere, and oceans. The major processes moving water are evaporation, transpiration, condensation, precipitation.
  • T Value (Tolerable Soil Loss) - - Maximum amount of soil loss in tons per acre per year that can be tolerated and still permit a high level of crop productivity to be sustained economically and indefinitely.
  • Detachment-- Separation of soil particles from the soil mass. Expressed in units of mass/area.
  • Deposition -- Accumulation of sediment on the soil surface. Expressed as mass/acre.
  • Nitrogen Cycle -- Cycling of nitrogen through the biosphere through 4-step process: nitrogen fixation, decay.
  • Operational--
  • Contour Buffer Strips – permanently vegetated strips located between larger crop strips on sloping land.
  • Contour Farming – aligning ridges, furrows, and roughness formed by tillage, planting and other operations to alter velocity and/or direction of water flow to around the hill slope.
  • Cover Crops – crops including grasses, legumes, and forbs for seasonal cover and other conservation purposes.
  • Crop Rotation – growing plants in a planned sequence on the same field.
  • Managed Grazing (Rotational Grazing) – Managing the planting of forage and using grazing rotations among fields or paddocks.
  • Nutrient Management – managing the amount (rate), source, placement (method of application), and timing of plant nutrients and soil amendments.
  • Integrated Pest Management – a site-specific combination of pest prevention, pest avoidance, pest monitoring, and pest suppression strategies that prevent or mitigate off-site pesticide risks to water quality.
  • Residue and Tillage Management – limiting soil disturbance to manage the amount, orientation and distribution of crop and plant residue on the soil surface year round.
  • Structural--
  • Diversion – a channel generally constructed across the slope with a supporting ridge on the lower side.
  • Field Borders – a strip of permanent vegetation established at the edge or around the perimeter of a field.
  • Grassed Waterways – areas planted to grass or other permanent vegetation where water usually concentrates as it runs off a field.
  • Buffer Strip – vegetated areas next to water resources that protect water resources from nonpoint source pollution and provide bank stabilization.
  • Stream Bank and Shoreline Stabilization – treatment (s) used to stabilize and protect banks of streams or constructed channels, and shorelines of lakes, reservoirs or estuaries.
  • Terraces – an earth embankment, or a combination ridge and channel, constructed across the field slope.
  • Windbreak – single or multiply rows of trees or shrubs in a line that reduce wind erosion.
  • Water and Sediment Control Basin – a basin with an engineered outlet, formed by an embankment or excavation or a combination of the two that captures and detains sediment run off to allow it to settle out in the basin.

Background – Agricultural Connections (what would a teacher need to know to be able to teach this content)

  • This publication ( http://www.extension.iastate.edu/agdm/crops/html/a1-41.html ) has helpful images of the conservation practices mentioned.
  • Most of the vocabulary words relate to conservation methods. While they all hold value to someone, they might not all hold value to every farmer.
    • Different landforms or features will dictate what kinds of practices will be most beneficial. For instance, if a field is mostly flat, contour farming will not be a helpful practice, because there is nothing to contour around. However, managing tillage and residue can be a positive way for that farmer to maintain the integrity of their flat field.
    • These practices may also have varied costs associated with them. Especially the structural conservation practices will have costs associated with integration, and will likely need maintenance over the years to ensure that it continues to do its job.
      • Some of the operational conservation practices, such as nutrient management, can be budgeted for more easily, however. For the Low cost of soil tests, the farmer can calculate exactly the amount of fertilizers needed for their land. This can save the farmer money on fertilizer costs immediately upon implementation.
        • Conservation practices that focus on the long-run of saving soil also have financial benefits, but this value is less visible. Here is a link to an extension article outlining the dollar value of erosion in various Iowa counties: https://www.extension.iastate.edu/agdm/crops/html/a1-75.html. The average cost per acre in 2012 over the 20 counties evaluated was $339.
    • When looking at conservation efforts purely from an erosion reducing standpoint choices may seem obvious. However, if the discussions in your classroom turn this way, encourage students to think about alternative factors. It might be beneficial to do some calculations of current corn prices (generally around $3.50-ish), bushels per acre (189 bu/acre average corn in 2015), average farm size (333 acres), cost of inputs, etc., to see the kinds of disposable income the farmer might be able to put forth for these practices. Then, revisit the cost of not implementing conservation practices. Help students objectively weigh the pros and cons of implementing short or long-term conservation practices.
  • Some of the vocabulary words refer to types of erosion and other conservation buzzwords. While some are relatively self-evident, others are more complicated.
    • T Value is one of the more complicated concepts. In Iowa, we generally measure this by 1-5 tons per acre per year of soil loss. As a reference, the flattest lands in north-central Iowa can tolerate 5 tons per acre per year of soil loss, and therefore they do not need to worry as much about conservation tillage, etc. However, the older, more weathered, thinner soils in southern Iowa could have a T value of 1 ton per acre per year of soil loss, meaning that the land should be kept in a perennial crop (such as hay or pasture) to minimize any erosion. Realistically one ton per acre per year is a very small amount of soil, and this amount can be lost even on a native prairie vegetated soil. However, that does not mean that we need not try to prevent soil loss.
      • These values are defined per soil series within soil survey books. Many farms off “the Lobe” (the area of flat land in the north-central part of the state) have a T value of 3 tons per acre per year. “The Lobe” will generally have T values closer to 5. Land with T values of less than 3 should be put in perennial crops and not used for row crops.
    • The Nitrogen Cycle might be touched on if any conversations about nitrates in the water come up in class. Essentially, there is a lot of nitrogen available in the air (more than 75% of the air), but it is in a form that is unavailable to living things. So, various bacteria are able to break down N2 into more available forms for plants to use and for animals to eat once the plants do use them.
  • This lesson will require some preparation before class. You will need to print one copy of the Vocab Words attached document and cut apart enough cards for each student to match with another student (word and definition), as well as enough copies of the graphic organizer for each student.
  • If desired, you could also provide a copy of the complete vocab list to each student.

Interest Approach or Motivator

Prior to class time, print the document Soil Conservation Vocab Words.docx and cut along the lines. For the motivator activity, you will need one strip (either vocab word or definition) for each student in class. There are 28 vocab words listed with definitions, so you may pick and choose words that could work well with your students’ prior knowledge.

Hand each student a card with a key term or definition of key term as they walk in the door. The student’s card will either have a key term from the vocabulary or a definition that matches a key term.  Instruct the students to find the person that matches their card and sit next to them and wait for further instructions. 

Procedures

  1. After students have found their partner, have them share their term and definition with the class to determine if they paired up correctly.
  2. As a review ask students what similarities or differences they noticed in the vocab words. What are some consequences of erosion?
  3. Ask students to discuss and brainstorm with their partner ways erosion can be prevented.
  4. After a few minutes of discussion in partners, have each group report and share the highlights of the small group discussions.
  5. Take a few minutes to review types of erosion and operational vs. structural conservation methods. Open the attached PowerPoint (Types of Erosion.pptx), and go through it as a class. Tell students to ask questions as they think of them.
    1. The PowerPoint is organized into types of erosion, conservation practices, conservation definition, watershed definition, and T value definition.
      1. When talking about the four main types of erosion, ask students to think of how those types occur and how they could be managed. Tell students to think about how landforms or land features could impact these erosion types.
      2. When following up with other definitions, ask students how these terms may tie into the overall conservation discussion. For instance, why might we care about the watershed if we are talking about erosion?
  6. Hand out the blank graphic organizers and have students get their writing utensil. Go through the graphic organizer as a class. Ask students if they have any questions about the different headers (description, purpose, etc.).
    1. Ask students do define operational vs. structural conservation methods. This was previously covered in the PowerPoint.
  7. Have students pair up with their original partner from the beginning of class. Each pair of students will work together to fill out the graphic organizer.
    1. One student could research while the other records, they could split the list in half, or they could split the list by headers instead of erosion control measures.
  8. Give the students some time to fill in the graphic organizer (about 15-20 minutes).
  9. When the allotted time is up, bring the class back together. Ask students what they noticed while researching these various efforts.
    1. What types of measures seem most effective? What seems easiest? What kinds of things are farmers looking to conserve? Why does conservation appear to be a concern?
  10. Have a discussion with the class about conservation efforts. Ask the class to pretend they are farmers. Their land is relatively hilly. What kinds of efforts would you want to implement? What kinds of factors would you want to keep in mind?
    1. Remind students of factors like cost, soil compaction, length of seasons, and weather patterns in Iowa.
  11. Once the discussion is wrapped up, assign each student a conservation effort. Tell them that they will be responsible for creating a PowerPoint presentation on the effort.
    1. Tell them they will need to discuss the outcomes on biodiversity, the environment, agricultural systems, etc.
    2. Also outline ease of implementation, cost, and effectiveness of conserving soil and maintaining water quality.
  12. Give students one class period to work on their presentation. The next lesson (lesson 3) will be dedicated to showing the presentations to the class.

Essential Files (maps, charts, pictures, or documents)

Did you know? (Ag facts)

  • Implementing erosion control practices is one of the most effective ways to protect the soil and land that grows our food.
  • 5 tons/acre/year of soil loss is the maximum tolerable loss for soil in Iowa

Extension Activities (how students can carry this beyond the classroom)

Follow up with activities about watersheds and runoff in cities and rural areas.

Sources/Credits

Precision Conservation Planning Curriculum—Iowa State University, Department of Agricultural Education & Studies

Author:

Anita Fisher

Chrissy Rhodes

Organization Affiliation:

West Bend-Mallard Community School

Iowa Agriculture Literacy Foundation                

National Agriculture Literacy Outcomes

  • T1.9-12.b -- Describe resource and conservation management practices used in agricultural systems (e.g., riparian management, rotational grazing, no till farming, crop and variety selection, wildlife management, timber harvesting techniques)
  • T1.9-12.a -- Describe how wildlife habitats are created and maintained by farmers/ranchers and why these habitats are important (e.g., promoting pollinator habitat, insect refuges, creating buffer zones for nutrient management, etc.)

Iowa Core Standards

Science:
  • HS-LS2-7. Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
  • HS-ESS3-4. Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.
Language Arts:
  • SL.11-12.4-- Present information, findings, and supporting evidence, conveying a clear and distinct perspective, such that listeners can follow the line of reasoning, alternative or opposing perspectives are addressed, and the organization, development, substance, and style are appropriate to purpose, audience, and a range of formal and informal tasks.

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