AGR_2320 LAB # 2 Physical Properties of Soils (1)
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University of Guelph *
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Course
2320
Subject
Geography
Date
Dec 6, 2023
Type
Pages
4
Uploaded by ProfWillpowerPartridge28
LAB # 2 Physical Properties of Soils
1.
After reviewing the video and testing the methods in the lab, determine the texture
of soil collected from 2 locations around your home or a location of your choice.
Complete table 3 to show the results of the tests. The soil can be collected from farm
fields, flower beds (below any mulch), or whatever location is easily available to you.
Be sure to indicate where you collected the soil (address plus was it a yard, field ,
flower bed ...)
soil
Ribbon test Length
of ribbon (cm), plus
texture estimate
Feel test
Texture estimate
Overall textural
category estimate
Soil 1 (Guelph lake)
No Ribbon (falling
apart)
Very Grainy
Sand
Soil 2 (143 Kortright
- Backyard)
2.6cm
Sticky but still grainy
Clay loam
2.
The texture may also be estimated using the “mason jar test” (any type of glass jar
will work) described in the following web link
(https://hgic.clemson.edu/factsheet/soil-texture-analysis-the-jar-test/). Note that the
mason jar method as given in the video is unlikely to result in all of the aggregates
breaking apart, which may result in an overestimation of the sand content and
under estimation of clay, so it should only be used as an estimate of texture.
Complete the Mason jar test for the same two soils used in the hand test for soil
texture and input your results in table 4. In addition to filling out table 4 include a
picture of your mason jars at the end of each test to show the thickness of each layer
Soil 1
Soil 2
Thickness of sand layer
2.5cm
2cm
Estimate of the % sand in sample
60%
50%
Thickness of silt layer
1.5cm
1.5cm
Estimate % silt in sample
35%
37%
Thickness of clay layer
0.2cm
0.5cm
Estimate % of clay in sample
5%
13%
Overall textural category of sample
Sandy loam
Loam
3.
Question 3. The time it takes for each particle size to fall out of the range of the
hydrometer is calculated using Stokes law as modified and discussed in class. Use
the equation given below to calculate the amount of time for all particles of the sizes
listed in table 5 to fall 12 cm out of suspension in still water.
Radius (cm)
Calculation (show work)
Time required to drop 12cm
0.001
12/(34,700)(0.001)^2
345.82s
0.0003
12/(34,700)(0.0003)^2
3842.46s
0.0001
12/(34,700)(0.0001)^2
34,582.13s
4.
Use the data in table 6 to complete figure 2
Figure 2.
The Particle Size Distribution (um) of A (green) and B (red). Both represent a positive
trend in percent equal to or less than indicated size and particle diameter, being at its greatest in
the sand portion.
5.
Question 5. Use the information in figure 2 to determine the sand, silt and clay
content of soils “A” and “B”along with the textural category of each of the soils.
Input this information in Table 7.
Soil
%sand
%silt
%clay
Textural category
A
32%
43%
25%
Clay loam
B
60%
30%
10%
Sandy loam
6.
Examine the display and figure 4 to help fill in table 5:
Turbidity
(yes/no)
Likely to slake
(yes/no)
Likely to crust
(yes/no)
Potential for
erosion (high/low)
High organic
matter
No
No
No
Low
Low organic
matter
Yes
Yes
Yes
High
I. What factor(s) are responsible for the result on the 2 soils (figure 4)?
High organic matter has low erosion and nonsusceptibility to all points. Soils with a high
quantity of organic matter generally have smaller particles and stronger structures. Thus, they are
less likely to dissociate in water, preventing turbidity. In being bonded together by organic
matter, they are less likely to destabilize, minimizing erosion, slake, and crust. Soils with low
organic matter are composed greatly of clay and silts. These particles have less rigidity and
separate easily in water. Their decreased aggregation and loose structure result in turbidity, slake,
crust, and erosion. Organic matter creates stabilized and strong structures.
II. What are the implications of slaking and crusting?
Slaking breaks down soil structure immensely. This makes the soil more susceptible to erosion,
as the particles are likely to be taken with water runoff. They can also cause dense structures,
inhibiting filtration from the water. This prevents proper hydration for receiving nutrients,
harming any organic matter within the soil. Crusting works to create a strong barrier that plants
can not penetrate. This inhibits growth of matter within the soil and creates a nutrient imbalance.
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This crust also limits interaction with the external environment, prohibiting nutrient exchange
and various forms of respiration.
7.
Review the method of taking a bulk density core and the methods of calculation of
bulk density and pore space ratio from the lecture. For your calculation of pore
space ratio assume a soil particle density of 2.65 g cm-3. Calculate the bulk density
and pore space ratio of the three soils in table 7
Core #
Volume of core
(
cm
3
)
Oven dry
weight of core
(g)
Bulk density
Pore space ratio
1
86
114
1.32
0.5
2
86
93
1.08
0.6
3
86
127
1.48
0.44
8.
Which soils would have predominantly macropores, micropores, or a mixture?
Record this information in table 8 Consider the magnitude of each of: bulk density,
shrink-swell potential, and compressibility and rate each soil, relative to the other
soils as high, H, medium, M, or low, L and fill this information in table 8
Soil patent
material
Relative proportion of
Macro vs Micro pores
Bulk density
Shrink-swell
potential
Potential
for
compaction
Outwash sand
plain
Mostly Macro
High
Low
Low
Lacustrine clay
plain (well
structured)
About the same
Low
High
High
Esker
Mostly Macro
High
Low
Low
Ground
moraine (silt
loam well
structured)
About the same
Medium
Medium
Medium