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Essential Questions

How is topsoil being lost?

How might the landscape or other factors impact how much sediment is lost?

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Erosion Demonstration

Predict:

I predict that...because...

Observe:

Explain:

There are two containers of equal size and soil. In one container, there is a plant growing. In the other, there is only soil. If water is poured into each container, and then collected after it passes through the soil, what will happen?

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Problem Solving for TomKat Ranch

TomKat Ranch is an 1800-acre grassfed cattle ranch in Pescadero in the San Francisco Bay Area.

Their team of ranchers, scientists, and advocates look to nature to guide their landscape management in support of their values.

Over the next five years, they want to have inspired the transition of one million acres of California rangeland to regenerative management.

To do this, they have taken data about their land to determine soil health and where topsoil is being lost.

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Careers in Agriculture

A landscape coordinator may serve a variety of roles, such as monitoring which activities occur at certain areas and brainstorming new ways to grow food like “no dig gardening”

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Analyzing Ranch Data

Guiding Questions:

What type of data is being displayed?

What do you think it means?

What are the two keys?

What information do they provide?

What might be causing the areas to have different results?

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Water Infiltration

Water infiltration is an indicator of soil compaction
Water infiltration rate is measured as the time required for soil to absorb water (minutes per inch of water)
Compacted soils take longer to absorb water, increasing runoff and decreasing water available for local plant growth
More runoff also leads to loss of topsoil and an increase in sediment in rivers, streams, etc.

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How Can We Measure Runoff/Erosion?

Secchi Disks help to measure water transparency or turbidity.

Water with high turbidity is not very transparent and does not let light through.

High turbidity water is often caused by sediment in the water due to runoff.

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Testing the amount of sediment in rivers

at the different Sites

To use the Secchi disk:

Hold the string and lower the secchi disk into the water. Continue to lower the disk until it disappears.
Pinch the string at the top of the water.
Measure the length between the disk and where you pinched the string.
Record the depth on your data sheet.

Site	Depth of Secchi Disk (in cm)	Observations
1
2
3
4

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Which “site” matches each location?

What impact will the rate of water infiltration have on the amount of soil that ends up into the rivers, streams and ponds?

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What would you do?

You notice that at Site D, the water takes a very long time to absorb into the soil.

You also notice that the nearby bodies of water have a high turbidity.

Because of the long water infiltration rate at Site D, most rainwater is running off, eroding the topsoil, and adding lots of sediment to the nearby bodies of water.

What are some specific things that you could do to reduce issues above?

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What would the landscape coordinator do?

What decision did the landscape coordinator make to help keep the soil in place?

The plants growing in the picture are not grown for food or to be sold as flowers.

What is “missing” in the picture and what could they have done better?