Stream table experiment

Meher Banajee

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Students should work in groups of 3 or 4, or as materials allow. Each group will need a stream table, soil materials of one or more types to fill the table, a watering can, a collection pail for water and material that has passed through the stream table, various types of mulch as directed by the instructor, blocks of wood to raise one end of the table, pens, notebooks, and plastic protractor. In each test, roughly the same amount of "rain" should be allowed to fall on the soil so the results obtained will have some degree of consistency. 1. Fill the stream table to within 2 inches of the top with the soil type indicated by your instructor.

Using the blocks, raise the end of the table opposite the V notch about 1.5 inches. Let at least one pint of rain fall on the raised end of the table. Use the protractor to measure the angle of slope at each elevation. Describe the results. Repeat this process for elevations of 3, 4.5, 6, and 7.5 inches. At 7.5 inches elevation, the slope of the land is about 30 degrees; this is about the upper limit for row crop farming. Note the type and degree of severity of erosion obtained at each elevation. Which elevation causes the water to make the greatest erosion?

Links to reference material:
movie clips of sloped stream table

Your answer:
4.5"
3.0"
7.5"
1.5"
6.0"

Raise the table by 9" and sprinkle one pint of water directly on one spot on the soil. After the gully has been established, build a small check dam with pebbles across the gully. Allow an additional unit of rain to fall on the soil and record the results below:

Your answer:

Keeping the table at an elevation of 6 inches, smooth out all signs of previous erosion and create a series of 1/4 inch deep furrows about 1 inch apart parallel to the direction of water flow. Allow a unit of rainfall to fall on the soil and observe. Smooth off the soil again and make similar furrows at RIGHT ANGLES to the direction of flow of water. Provide a unit of rainfall, observe and record BOTH observations. Now compare the effects of both in a short answer.

Your answer:

Keeping the elevation at the 6 inch level, and using the selection(s) of mulch indicated by your teacher, place mulch evenly across the surface of your soil, being careful to cover all the soil in the test area. Test the effectiveness of each mulch by allowing a unit of rainfall to fall onto the mulch over the soil. Repeat this process with different mulches as directed by the teacher. Hay causes the most erosion followed by pine needles and shredded paper. Answer true or false.

Your answer:
TrueFalse

What effects did mulch/ground cover have on the erosion process? Were any types of mulch superior to others?

Your answer:
Shredded paper
Hay
Pine needles
They were the same

Some land has been describe as unsuitable for farming; or "will not support human populations". What does this mean and what factors can cause the soil to be described this way?

Your answer:
All of the above.
Tall crops will grow on this land.
None of the above.
Not many crops will grow on this land.
Plenty of crops will grow on this land.

If you tested more than one type of soil in the stream table, or if other groups of students tested other soils, obtain their data and compare to yours. Do all soils erode in the same fashion?

Your answer:

Contour plowing causes more erosion than parallel plowing. Answer true or false

Your answer:
TrueFalse

At what angle of slope did the erosion start to get really severe with your soil? What would have been the result of raising the slope of the land beyond this point? Explain.

Your answer:

If you were a farmer what kind of soil, elevation and furrows would you use? Explain your answer.

Your answer:

Name:

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Class:

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