Soil Ratios and Types
Using the formula below, calculate the percentage
of each soil type: sand, silt, or clay present in the soil column of half-pint
bottle. Record results on Table 2 Results of
Lab Report .
% sand = Depth of sand layer in mm. x 100 %
Total depth of soil in mm.
Determining Soil Type-Texture:
Use Figure 1 to determine the soil type for the sample as follows:
- Find each percentage on the proper axis of the soil triangle.
- Follow the dotted lines from each percentage to the point where they
intersect inside the soil triangle.
- Identify soil sample type by identifying the region of the soil triangle
that contains the point of intersection.
- If the dotted lines intersect on the boundary between two regions,
assign the soil type of the graph region of greater area.
Analysis:
As each lab group determines the soil type
of their samples, students place a mark inside the corresponding region
of the soil triangle. Answer the following questions:
- Do the marks fall in one area of the triangle?
- Which type of soil particle is most common in your region?
- Do some samples on the triangle fall outside the main cluster of
samples?
- Look at the features of the collection site. What factors at the
collection site are associated with those types of soil?
- Which two soil samples in class could be mixed to obtain the best
soil?
- Which soil sample will hold the most water?
- Which soil sample will be most subject to erosion?
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