Soil Profile AssignmentName: ______Period: _____
Purpose: In this lab you will be learning about how to test soil samples for the presence of various nutrients, as well as how to use these and other qualities of the soil to determine the habitat from the sample was taken.
Data Collection
The protocols for all the various tests are printed separately, so refer to the Protocol Packet to see how to do each test. Follow the directions carefully. Start the fractionation and percolation tests first since both of these procedures require a longer waiting time before results can be determined.
Soil Texture:
I. Determine the percent composition of different particle sizes in your sample(s) using fractionation. Record the values below. Determine the soil type by using the Texture triangle in the protocol packet.
Sample A: Location:____________mm of sand ______% sand
______mm of silt ______% silt
______mm of clay ______% clay
______TOTAL / Sample B:Location: ______
______mm of sand ______% sand
______mm of silt ______% silt
______mm of clay ______% clay
______TOTAL
Use the soil texture triangle to determine the soil type for each sample. Draw the lines that you use to determine the soil type on the soil texture triangle in different color pens.
Soil A type: ______Soil B type: ______
II. Percolation Rate and Water-Holding Capacity:
Follow the procedures Protocol Packet to determine the percolation rate and water-holding capacity of your sample(s). Record the data below:
Sample A: Location:______Time for water to stop dripping: ______min.
Amount of water collected: ______ml
Percolation Rate (amount÷time): ______ml/min
Water-Holding Capacity: ______ml / Sample B: Location:______
Time for water to stop dripping: ______min.
Amount of water collected: ______ml
Percolation Rate (amount÷time): ______ml/min
Water-Holding Capacity: ______ml
III. Soil Texture Flow Chart. Another way of determining soil type, in addition to the fractionation you have set up with the graduated cylinders is through the soil texture flow chart. Follow the directions in your packet to determine the soil type using this method. Be sure to wash your hands after handling the soil.
Sample A: Location:______Length of ribbon before breaking: ___
Texture by feel (gritty, smooth, etc.):
Other notes (describe soil characteristics):
Soil A Type: ______ / Sample B: Location:______
Length of ribbon before breaking: ___
Texture by feel (gritty, smooth, etc.):
Other notes (describe soil characteristics):
Soil B Type: ______
IV. Soil Nutrients:Follow the procedure for each of the nutrient/pH tests in the protocol packet.
Sample A: Location:______pH: ______Nitrogen:______
Phosphorus:______
Potassium:______/ Sample B: Location:______
pH: ______Nitrogen:______
Phosphorus:______
Potassium:______
Analysis Questions:
- Explain the relationship between percolation rate and water-holding capacity.
- How does the particle size (sand vs. clay) in your soil affect both the permeability (percolation rate) and water-holding capacity of a soil? Include an explanation of how pore space between particles relates to these different properties of soil.
3. Which of your samples contained more clay? Did you find the data you collected for permeability and water-holding capacity matched or contradicted your answer to Question #2? If your data contradicted your answer, why might this have been the case?
.
4. What are the advantages and disadvantages of soil having a high percolation rate for water?
5. What type of soil would have a moderate percolation rate which would balance the advantages and disadvantages of a high percolation rate? Describe the relative ratio of the different types of soil particles in this type of soil.
6. The amount of humus is another important soil characteristic which we didn’t measure in this lab. Define what humus is and explain how would you go about estimating the amount of humus in your soil samples.
7. Why is pH important to a soil? What happens if soil is too acidic? Too alkaline?
8. List the importance of each of the following nutrients: N, K, P (see soil test instructions, text, and the soil booklets for information on this).
9. Based on pH and nutrient content, which types of plants could your soil samples support (see handout from soil booklets)?
Sample A
Sample B
10. Describe how the nutrient content of your soil samples is related to the ability of the habitat from which they were taken to recycle essential nutrients. Were these habitats seemingly poor in any nutrients? If so, do you think those nutrients might have been present in the habitat in places other than the soil? Explain.