Introduction
Soil is the basic resource to all life. Without the proper soil, a tree will not grow to its optimum size or condition. We should learn all we can about the soil, such as how it affects animals, microorganisms, weeds, shrubs, flowers, people and trees. The size and texture of the particles plays a big part in how the soil functions.

Things to look for in soil are color, texture, structure, depth, and reaction (pH). A general soil profile is made up of a litter layer, A horizon, B horizon and C horizon. A soil sampling device allows you to gather data on the soil makeup on any site.

Questions

1. What texture class is this soil?
2. What is the particle size make-up of this soil?
3. Are there different soils on the school grounds?

Hypothesis
     Students should make up their own before continuing.

Materials
1 Soil probe
1 Metric ruler
1 Quart jar with lid
1 Set index cards for diagrams

Procedure

1. Collect all needed materials and prepare data tables for this exercise.
2. Use the soil probe to collect soil cores as deep as possible from a site determined by your teacher.
3. For one of the cores, diagram and measure the depth of each layer or horizon in your sample. Make a representative diagram, if necessary.
4. Collect enough cores to fill the quart jar at least half and no more than two thirds full.
5. Fill the rest of the jar with water, seal tightly and shake vigorously for 10 minutes. You may want to share the task with your partners.
6. Let the jar stand for 24 hrs. Make sure it is labeled with your name and period.
7. The next day, mark the soil layers of each sample on an index card placed behind the bottle. Mark the top of the soil and the points where the layers change.
8. To find the percent of sand, silt and clay in your sample measure the marks on the card for: 1) entire height, 2) sand (bottom) layer, 3) silt (middle) layer, and 4) clay (top) layer. Then take the height of each layer by the total height and multiple by 100. Record the figures on the data sheet.
9. Make a diagram of the soil cores, soil profile from the quart jar and label both.

Analysis of Results

1. At which site was the soil the most sandy? silty? clayey?
2. Do you think that this is a trend and would be found at other sites? Explain.
3. What are some factors that may change the results of this experiment? Explain.

Discussion Questions

1. Is the soil at the site of each tree different? Is there some trend that you can see?
2. Look in one of the resources and find out what type of soil one of your trees require, and see how this compares.

Conclusions

1. Did you achieve your hypothesis? Explain.
2. What did you learn by doing this exercise?
3. If you were to look at more trees, what type of sites would you choose to visit? Give at least 3, with reasons for each.

Table A:

Soil Profile

Sample No.	Site	Litter depth	A horizon depth	B horizon depth	DEPTH of Change
.	.	.	.	.	.
.	.	.	.	.	.
.	.	.	.	.	.
.	.	.	.	.	.

Table B:

Soil Texture

Sample No.	Site	Stand	Silt	Clay	Total	% Sand	% Silt	% Clay
.	.	.	.	.	.	.	.	.
.	.	.	.	.	.	.	.	.
.	.	.	.	.	.	.	.	.
.	.	.	.	.	.	.	.	.

Background Information
Soil particles vary greatly in size. The largest particles settle to the bottom first. The fine particles settle slowly; some are suspended indefinitely.

Soil scientists classify soil particles into sand, silt and clay. Scientists use these three components and the calculated percentages on the texture triangle to determine the textural class of the soil at a given site. Using the information in the Understanding Soils Bulletin #4052, and information from the other three soils bulletins, the students can find the textural class of a soil from this exercise.

Size of soil particles is important. The amount of open space between the particles has much to do with how easily water moves through the soil. This also determines how much water the soil will hold, which has a major effect on the type of plants that can grow in the soil.

Target Group
This exercise can be done with only slight modifications, for almost any grade level.

Timeline
This exercise will take two days: one to collect materials and set up the jars; one to gather and calculate the data.

Placement of Lab in Curriculum
This can be done at any time, but preferably for comparing soils to tree species or area found. It is best used to show how different species will grow.

Student Learning Objectives

1. Understanding the interaction among trees, soil and people.
2. Gathering, comparing and analyzing data.
3. Prepare a written report of soil types found.

Preparation and Teaching Tips

1. Soils can be measured with the soil corer, or hand shovels can be used to dig small but deep holes to gather soil down at least to 15 inches. The deeper the soil core to be analyzed the better.
2. Fill a one quart Ball and Mason jar with water about two thirds of the way. Then add the soil until almost filled. (If in the field, put soil in the jar about 1/2 way and then fill with water back in the lab.)
3. Shake the jar vigorously for at least 10 minutes. Allow to settle over night.
4. Place a index card behind the jar and mark each of the layers on the card and then measure.
5. Finally, calculate the percentage clay, silt, and sand from the total and apply this to the texture triangle to determine the soil type.

References

1. Teaching Soil and Water Conservation: A Classroom and Field Guide. US Department of Agriculture Program Aid #341.
2. Understanding Soils. VAS Bulletin #4052.
3. Soil Texture. VAS Bulletin #4030.
4. Soil Color. VAS Bulletin #4029.
5. Soil Structure. VAS Bulletin #4028.

Discussion Question Answers

1. Answers will vary depending on the site.

Blowouts
The mass of the sample can be taken in a previously massed plastic bag using field scales. Soils can be dried and reweighed in the same plastic bag, for soil moisture calculations, if appropriate. This can provide comparisons with the soil meter readings. These meters are found with instructions in the Forester'sTrunk, or can be purchased at any garden supply store.

example data

Table A:

Soil Profile

Sample No.	Site	Litter depth	A horizon depth	B horizon depth	DEPTH of Change
006-34	forest	4 cm	34 cm	19 cm	4\38\57
006-22	field	6 cm	23 cm	10 cm	6\29\39
.	.	.	.	.	.

Table B:

Soil Texture

Sample No.	Site	Stand	Silt	Clay	Total	% Sand	% Silt	% Clay
tree 23	cy	3.96 cm	0.4 cm	4.4 cm	8.8 cm	45	5	50
tree 41	pw	2.04 cm	6.12 cm	2.04 cm	10.2 cm	20	60	20
grassy	field	1.75 cm	7.63 cm	4.62 cm	14.0 cm	12.5	54.5	33
.	.	.	.	.	.	.	.	.

Tree 23: soil is clay
Tree 41: soil is silt loam
Grassy: soil is clay loam