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Soil Health Comparison: Tillage Methods

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About This MicroSim

This MicroSim provides a time-lapse comparison of how two farming practices -- conventional tillage and no-till farming -- affect soil health over 20 simulated years. Side-by-side cross-section views of soil profiles start identically, then diverge dramatically as seasons advance.

On the conventional tillage side, students observe topsoil thinning, organic matter decreasing (soil lightens in color), a compaction layer forming, fewer visible organisms (earthworms and roots decline), and increased surface erosion during rain events. On the no-till side, the topsoil remains stable, organic matter accumulates (soil darkens), root networks extend, earthworm and fungal populations grow, crop residue builds on the surface, and water infiltrates more effectively.

Metrics panels track five key indicators -- soil organic carbon percentage, water infiltration rate, erosion rate, earthworm count, and crop yield -- with line graphs showing trends over the 20-year period. This visualization makes decades-long soil processes visible in seconds, connecting farming decisions to ecological outcomes that are normally invisible.

How to Use

  1. Observe the two identical side-by-side soil profiles: conventional tillage (left) and no-till (right).
  2. Click Advance Season or Play to progress through years and watch both profiles change.
  3. Compare the visual changes: soil color, topsoil depth, organisms, root networks, and surface erosion.
  4. Monitor the metrics panels showing soil organic carbon, infiltration rate, erosion, earthworm count, and crop yield.
  5. Watch the line graphs tracking each metric over the 20-year simulation.
  6. Click Reset to restart the comparison from year zero.
  7. Pay special attention to what happens to crop yield -- does no-till match conventional tillage over time?

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

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<iframe src="https://dmccreary.github.io/ecology/sims/soil-health-comparison/main.html"
        height="567px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

9-12 (High School Biology / AP Environmental Science)

Duration

45 minutes

Learning Objectives

  • Evaluate the long-term effects of conventional tillage vs. no-till farming on soil health indicators.
  • Analyze how farming practices affect soil organic carbon, water infiltration, erosion, and biodiversity.
  • Assess the trade-offs between short-term agricultural productivity and long-term soil sustainability.
  • Propose evidence-based farming recommendations that balance yield with soil conservation.

Prerequisites

  • Understanding of soil horizons and basic soil properties
  • Familiarity with the concept of sustainable vs. unsustainable resource use
  • Basic knowledge of agriculture and food production

Standards Alignment

  • NGSS ESS3.C: Human Impacts on Earth Systems
  • NGSS ESS3.A: Natural Resources
  • AP Environmental Science: Topic 5.3 - The Green Revolution; Topic 5.5 - Soil Degradation and Conservation

Activities

  1. Engage (5 min): Show a photograph of the Dust Bowl era (1930s). Ask students what caused it and whether it could happen again. Introduce the connection between tillage practices and soil loss. Explain that the US loses about 1.7 billion tons of topsoil per year to erosion.

  2. Explore (15 min): Students run the simulation through all 20 years, recording the five metrics at year 0, year 5, year 10, and year 20 for both farming methods. They create a comparison table and identify which metrics diverge the most.

  3. Explain (15 min): Discuss the mechanisms: conventional tillage breaks up soil structure, exposes organic matter to oxidation, destroys fungal networks, compacts subsoil, and leaves the surface vulnerable to wind and water erosion. No-till preserves soil structure, allows organic matter to accumulate, supports soil food webs, and maintains water infiltration. Discuss why no-till yields may be lower initially but stabilize or improve over time.

  4. Extend (10 min): Students role-play as agricultural advisors. A farmer is considering switching from conventional tillage to no-till but is worried about short-term yield loss. Using data from the simulation, students write a recommendation letter that addresses the farmer's concern with evidence from both the 5-year and 20-year timescales.

Assessment Questions

  1. Compare the soil organic carbon levels after 20 years of conventional tillage vs. no-till farming. What explains the difference?
  2. Why does water infiltration rate decrease with conventional tillage but increase with no-till? What are the downstream consequences of reduced infiltration?
  3. A farmer says, "Conventional tillage gives me better yields, so it must be the better method." Using the 20-year data from this simulation, write a response to this claim.
  4. How do soil health practices on farms connect to broader environmental issues like water quality, climate change, and biodiversity?

References

  1. Montgomery, D.R. (2007). Dirt: The Erosion of Civilizations. University of California Press.
  2. Lal, R. (2004). Soil carbon sequestration impacts on global climate change and food security. Science, 304(5677), 1623-1627.
  3. USDA: Soil Health. https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health