Water Quality: Nutrient Management and Cropping Systems - Riparian Areas - Lesson 16

Water Quality: Nutrient Management and Cropping Systems - Riparian Areas - Lesson 16

Target Grade Level / Age Range:

Grades 9-12

Time:

50 minutes

Purpose:

Students will understand the importance of riparian areas and wetlands to help manage water and remove excess nutrients.

Students will design a plan for a constructed wetland as part of a watershed improvement plan.

Materials:

  • Worksheets and background information – enough for each group of students

Suggested Companion Resources (books and websites)

Vocabulary (with definitions)

  • Wetland: shallow vegetated pools that help filter pollutants, control flooding and provide wildlife habitat.
  • Riparian: Refers to site conditions that occur near water, including specific physical, chemical, and biological characteristics that differ from upland (dry) sites
  • Saturated Buffer: allow nutrients to be removed by redistributing tile water into the riparian buffer soil profile before reaching the stream
  • Constructed Wetland: A shallow vegetated pool that helps filter nutrients, especially nitrate, reduce flooding and provide wildlife habitat.
  • Berm: a flat strip of land, raised bank, or terrace bordering a river or canal
  • Weir: a barrier across the horizontal width of the river that alters the flow characteristics of the water and usually results in a change in the vertical height of the river level

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

Nutrient enrichment of water resources by inputs of nitrogen and phosphorus, which can lead to eutrophication is still a water quality problem in agriculturally dominated watersheds around the world. Internationally, wetlands both constructed and natural are increasingly being used to help reduce both point and non-point source nutrient and contaminant loss from agricultural practices.

Nutrient treatment wetlands – also called “constructed wetlands” – are an important edge-of-field practice. The wetlands designed and installed under the Conservation Reserve Enhancement Program (CREP) have been shown to improve water quality by reducing nitrate by an average of 52 percent. Actual nitrate removal depends on rainfall, with more removal in drier years and less removal in wetter years. In addition to removing nutrients, wetlands provide wildlife habitat, recharge groundwater, reduce flooding downstream by storing runoff, and can provide recreational opportunities.

Wetlands are a crucial part of our ecosystem. Their purpose is to soak up water, controlling periods of flood and re-releasing it when necessary. Wetlands also have the capability to slow down the flow of water across a landscape, thus removing contaminants from flowing water. In addition, the microbes associated with the wetland plants more efficiently remove nitrate than the plants themselves. Wetlands are also important for the number of wildlife species are attracted to them: from birds to aquatic life.

In agriculture, farmers can mirror nature through constructed wetlands. These pools are a very useful tool to filter runoff from cropland, feedlots, aquaculture operations, and agricultural processing facilities. The CREP wetlands are primarily designed to treat runoff from cropland.

Constructed wetlands are man-made features that mirror the natural function and benefit of wetlands. By following engineering designs, you can construct your own wetland near the edge of your field to control water movement, remove nitrate and enjoy the wildlife habitat. Through the CREP program, farmers across Iowa are constructing their own wetlands, which are effective at reducing peak flows, and removing sediment, and nitrate.

More than 70 constructed wetlands have been installed in Iowa for water quality as part of CREP. It is estimated that Iowa needs about 7,000 CREP wetlands to fully implement the Iowa Nutrient Reduction Strategy. CREP is a major state/federal initiative of strategically located wetlands using advanced computer technology and designed to remove nitrate from tile-drained water from cropland. These systems typically include a 5 to 10 acre wetland, surrounded by a 30 to 40 acre grass buffer. The typical system handles water from roughly 1,000 acres. One CREP wetland provides roughly the same amount of nitrate removal from 1,000 acres as converting 500 acres to permanent grass.

Interest Approach or Motivator

Share the video on the Nutrient Reduction Strategy (slide #2). Pose the questions and facilitate conversation.

Procedures

  1. Teach the content in slides 3-12 in the accompanying PowerPoint.
    1. Nutrient treatment wetlands – AKA “constructed wetlands” –
    2. Edge-of-field practice
    3. Designed and installed under the Conservation Reserve Enhancement Program (CREP)
    4. CREP wetlands are primarily designed to treat runoff from cropland
    5. Shown to improve water quality by reducing nitrate by an average of 52%
    6. Provide
      1. wildlife habitat,
      2. recharge groundwater,
      3. reduce flooding downstream by storing runoff
    7. provide recreational opportunities.
    8. Soak up water, controlling periods of flood and re-releasing it when necessary.
    9. Slow down the flow of water across a landscape, removing contaminants from flowing water
    10. Microbes associated with wetland plants efficiently remove nitrates
    11. Man-made features that mirror the natural function and benefit of wetlands
      1. Utilize ditch plugs, dams, levees, dikes, and dugouts
      2. Grade or level land with machinery
      3. Plug subsurface drain tile or install water level control structure
      4. Plant native shrubs, trees, grasses
      5. Direct water flow with pipes, chutes, berms, and weirs
    12. More than 70 constructed wetlands have been installed in Iowa
    13. Estimated that Iowa needs about 7,000 CREP wetlands to fully implement the Iowa Nutrient Reduction Strategy
    14. Systems typically include a 5 to 10 acre wetland, surrounded by a 30 to 40 acre grass buffer
    15. Systems typically handles water from roughly 1,000 acres
    16. One CREP wetland provides roughly the same amount of nitrate removal from 1,000 acres as converting 500 acres to permanent grass.
    17. Vegetation Types in wetlands
      1. Emergent – plants that grow mostly out of the water
      2. Floating – plants with primary photosynthesizing leaves float on the surface of the water
      3. Submerged – plants just below the surface of the water
    18. Occur along watercourses and water bodies.
      1. flood plains
      2. streambanks and river banks
      3. Adjacent to ditches, canals, ponds, lakes, and reservoirs
    19. Different from surrounding lands because of unique soil and vegetation characteristics influenced by the presence of water
    20. General indicators of riparian areas include:
      1. Vegetation: kinds and amounts of vegetation differ from adjacent upland vegetation because more water is supplied to plants
      2. Soil: stratified sediments of varying textures that are subject to intermittent flooding or fluctuating water tables
      3. Water: direct influence by water from a watercourse or water body.
    21. Hydrology (movement of water)
      1. Ground water is generally nearer to the surface and available for plants.
      2. Fine-textured sediments are able to hold large amounts of water.
      3. Nutrient-rich ecosystem with sedimentation of organic matter and dissolved nutrients in the water.
      4. Periodic flooding allows water to move through soils enhancing the recycling of nutrients and other chemical reactions beneficial to plant growth.
      5. The timing of flooding enhances survivability of organisms, promotes species diversity, and biological productivity.
    22. Base flow (normal water flow in a river or stream)
      1. Alluvial soil, which is sedimentary material deposited by flowing water, is usually deep and stores large amounts of water from rainfall and runoff.
      2. Water flowing in a stream that is due to ground water seepage into the channel is maintained by riparian vegetation that shades the water, keeping it cooler and slowing evaporation.
    23. Nutrient cycling
      1. Nutrients are exposed to mechanisms that may use or change them.
      2. Nitrogen, phosphorus, calcium, magnesium, and potassium, are taken up by shallow-rooted riparian vegetation.
      3. Dissolved nutrients moving with the ground water and those that are leached in the soil may be taken up by deeper-rooted riparian vegetation.
      4. Some nutrients pass through without being detained, and some may be reintroduced into the water column when the vegetation dies and decomposes.
    24. Energy transfer
      1. Energy from dead plant matter (litter) is made available to in-stream animal communities to use and those downstream.
    25. Downstream flooding
      1. Reduces downstream flooding.
      2. Plants resist the flow and dissipate the energy.
      3. Increase the time available for water to infiltrate into the soil and be stored for use by plants.
    26. Water quality
      1. Reduced water velocities allow for sediment and organic matter to settle out of water.
    27. Aquatic life
      1. Rooting herbaceous and woody vegetation provide habitat and stabilizes streambanks.
      2. Plants reduce erosion and can create overhanging banks that serve as habitat for fish.
    28. Terrestrial life
      1. Extremely productive and have diverse wildlife.
      2. Provides corridors for migratory wildlife as forested connectors between habitats.
  2. Students will look at the Beaver Creek Watershed background information. Pass out at least one copy per group. Break the class into small groups (3 or 4 students works well). Distribute the Beaver Creek Watershed worksheet and have students work in groups to develop a plan and respond to the questions based on the information in the background document.
  3. Based on time, students can present their plan to the entire class or submit their written work to the instructor.

Wrap up class by passing out copies of the Beaver Creek Watershed Improvement Plan. Facilitate a conversation with students on how their plans compared to the plan that the watershed authority came up with.

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

Did you know? (Ag facts)

  • Iowa has diverse wetlands that include prairie-pothole marshes, swamps, sloughs, bogs, fens, and ponds.
  • Wetlands cover about 1.2 percent of Iowa, but about 200 years ago more than 11 percent of the State's area was wetland.
  • Conversion of wetlands to agricultural lands, largely in the prairie-pothole region, has been the primary cause of wetland loss.
  • Wetland acreage has been slowly increasing since 1987 as a result of the Prairie Pothole Joint Venture, a cooperative Federal, State, county, and private-organization program.
  • The Wetland Reserve Program of the 1990 Food, Agriculture, Conservation, and Trade Act has the potential to add a substantial number of additional acres.

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

  • Students can contact the Upper Cedar Watershed Management Authority (or another watershed authority) and interview them on their watershed plan.
  • Students can contact a local soil and water conservation district and interview them about watershed management and riparian areas.
  • Students can contact a representative from the Iowa Department of Agriculture and Land Stewardship and interview them on watershed management, water quality, and riparian areas.
  • Students can contact a representative from the Iowa Department of Natural Resources and interview them on watershed management, water quality, and riparian areas.
  • Students can interview someone involved in watershed planning to discover career options in this field.
  • Have students explore the People in Ecosystems/Watershed Integration app. Tutorial: https://www.youtube.com/watch?v=nbSuPS1gkaw App: http://www.nrem.iastate.edu/pewi/app/

Sources/Credits

Lesson plan development was funded by the Resource Enhancement and Protection Conservation Education Program (REAP CEP). Resource Enhancement and Protection Program (REAP): Invest in Iowa our outdoors, our heritage, our people. REAP is supported by the state of Iowa, providing funding to public and private partners for natural and cultural resources projects, including water quality, wildlife habitat, soil conservation, parks, trails, historic preservation and more.

Author(s)

Will Fett

Organization Affiliation

Iowa Agriculture Literacy Foundation

National Agriculture Literacy Outcomes

  • T1.9-12.c. Discuss the scientific basis for regulating the movement of plants and animals worldwide to control for the spread of potentially harmful organisms (e.g., invasive species and disease causing organisms such as foot and mouth disease and avian and swine flu) as well as the methods of control in place (state, national, and international policies, economic incentives)
  • 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

  • HS-LS2-2. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales. (riparian areas / buffer zones)
  • HS-LS2-7. Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity. * (no-till, buffer zones, riparian area management, bioreactors)
  • HS-LS4-6. Create or revise a simulation to test a solution to mitigate adverse impacts of human activity on biodiversity. * (buffer strips, riparian area management)
  • HS-ESS2-5. Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes. (water cycle, tiling, terracing, bioreactors, riparian areas)

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