Soil Texture Lab

Soil Texture Lab

Materials: 100 mL graduated cylinder

Three soil samples

Water

2 Rulers

Procedure:

1. Fill the graduated cylinder with 25 ml of your soil sample.

2. Add 75 ml of water to the graduated cylinder.

3. Cover the graduated cylinder with your hand and invert several times until the soil is thoroughly mixed. Add one scoop of alum.

4. Place the cylinder on the table and let it settle for approximately 30 minutes.

5. Once the soil has settled, there should be 3 distinct layers. Measure the volume of each layer and the total volume of the sample.

6. Calculate the percentage of each layer. (you will do this calculation 3 times- one for each layer)

Volume of layer 1,2 & 3 X 100% = % of sand, silt or clay

Total volume of soil

7. Use the Soil Texture Pyramid to identify the type of soil in your sample.

Directions for using a Soil Texture Pyramid:

§  Using a ruler, find the point along the base of the triangle that represents the percent of sand in your sample. Position the ruler on the line that slants in the direction that the numbers are facing for percent sand.

§  Place the edge of a second ruler at the point along the right side of the pyramid so that the ruler slants in the direction that the numbers are facing for percent silt.

§  Using a pencil put a dot where the two rulers intersect. You can check for accuracy by drawing a straight line to the right and that number should be the amount of silt that you have. The three percentages should add up to 100%.

8. Repeat the above procedure for the other soil samples.

9. Now that you have determined the type of soil samples that you have, use the soil texture by feel chart below and see if you get the same answers.

10. Once you have followed the flow chart for each of your soil samples, fill out the chart below with the results of the soil by texture test.

Analysis:

1. What is the relationship between soil texture and water?

2. Which types of soil can be mixed together to form the best loam?

3. What are the causes of erosion?

4. What can be done about erosion problems?

5. Which soil sample would be more subject to erosion?