Exam 1 Test questions- At least 90 of the points on your exam.docx

Exam 1 Test questions- At least 90% of the points on your exam
will be a selection of these
questions. Problems involving calculations will have altered
numbers.
1) Define or describe the following;
a) Reference state for soil water potential
b) Diffuse double layer
c) Soil bulk density
d) Soil water potential equilibrium
e) Cohesion
f) Soil water hysteresis
g) Porosity
h) Matric potential
i) Total soil water potential
j) Specific surface
k) Contact angle
l) Air entry matric potential
m) Volumetric water content
n) Time Domain Reflectometry
o) Gravimetric water content
p) Shrink-swell
q) Adhesion
r) Solute potential
s) Head units
t) Isomorphous substitution

u) Water characteristic function
2) Short answer-
a. If water exist in soil as films only (that is, water is only
coating particle surfaces),
explain why you would expect more water in a clay soil than in
a sand.
b. As a soil drains, is it true that small diameter pores drain
before larger diameter pores?
Explain.
c. For a given soil, is the bulk density a constant? Explain.
d. Explain why soil water would move from a drier to a wetter
soil. Or could it?
e. Does water drip from unsaturated soil? Explain based on
interfacial curvature.
f. It is often said that water always flow downhill. Is this true?
Explain.
g. Why do we need a reference state for the soil water potential?
List the properties of the
reference state.
h. Can an unsaturated sand pull water from an unsaturated clay?
Briefly explain.
i. Why does free water move against gravity into narrow
diameter pores?

3) Concise essay
a. Briefly describe the forces in soil which reduce the potential
energy of water relative to
the reference state.
b. Explain the purpose and basic operation of the pressure plate.
c. . Briefly describe the principle of operation of Neutron
Attenuation (neutron probe) and
Time Domain Reflectometry. What do these measure and how?
d. Concisely discuss the key physical and chemical
characteristics of the soil solid phase
involved with the adsorption and retention of water.
e. Briefly explain why some soils change dimension (swell)
upon wetting while others do
not.
f. A friend suggests that you use a tensiometer for the indirect
measurement of soil water
content. Briefly discuss the operation of the tensiometer, what
it measures, and list pros
and cons of using it for measuring soil water content.
g. A certain soil is known to change dimensions with changing
water content if the
dominant cation in the soil is calcium but not if the dominant
cation is potassium. Why?

4) Using a sketch, compare and contrast θ(h) for a fine and a
coarse textured soil. Explain the
similarities and differences (if any) between the curves.
5) A volume of soil (Vtotal) is the sum of the volume of pores
(Vpores) and the volume of solids
(Vsolids). Derive in a few steps the porosity φ expression
� = 1 − ��
��
where ρb is the soil bulk density and ρs is the particle density.
Quantitative
6) A bucket (20 cm diameter by 10 cm depth) contains a loam
soil with a particle density of 2.7
g/cm3 and a porosity of 40%. The soil is at a volumetric water
content of 0.10. If the bucket
receives 2.0 cm of rainfall,
a. Determine the soil water content after the rainfall (you may
assume that the rainfall
mixes uniformly throughout the soil volume).
b. Determine the weight of the bucket of soil after the rainfall
(you may disregard the
weight of the empty bucket).

7) A cylinder (4 cm diameter by 10 cm long) contains 210.0 g of
oven-dry mineral soil. Estimate
the grams of water required to fully saturate the soil in the
cylinder.
8) Suppose a layer of soil (20 cm thick, overlying impermeable
bedrock) has a known θ(h)
relationship
�(ℎ) = 0.46 �
−5
ℎ
�
0.25
If the soil is initially at h= -1000 cm, how much rainfall would
be required to increase h to -100 cm
throughout the soil layer? (You may assume that the added
water is mixed uniformly throughout
the 20 cm layer and that there is no evaporation or drainage
losses.)
9) Two soil samples, A and B, are placed next to each other
with good contact. Soil A is at
θ=0.28, while soil B is at θ= 0.15. The soil water characteristic
curve for each soil is

a. Will soil water move from one soil to the other? If so, which
sample will lose
water? Briefly explain.
b. Which soil would you argue has the narrower distribution of
pore sizes and why?
10) Suppose you have a homogeneous soil sample with a
volume of 100 cm3 and a known
moisture retention function (for h<-8 cm),
�(ℎ) = 0.48 �
−8
ℎ
�
0.15
0
50
100
150
200
250
300

0 0.1 0.2 0.3 0.4 0.5
So
il
w
at
er
te
ns
io
n
(c
m
)
Water Content (vol/vol)
Soil A Soil B
If the average matric potential of the sample is -2170 cm,
a. What is the water content of the sample?
b. How much water would you need to add to the soil sample
(assuming the water is
mixed uniformly with the soil) in order to increase the matric
potential to -100 cm?
c. What is the physical interpretation of the -8 cm in the
moisture retention function?

11) a. What do you need to know in order to determine the
direction of water flow between
two points?
b. The matric potential (or water pressure) is measured at three
soil depths. Use the data
in the following table to determine the direction of water flow
between depths 1 and 2
and depths 2 and
Soil depth (cm) soil texture h or p (cm) Pair (atm)
100 sandy loam -400 1
300 clay loam -80 1
400 loamy sand +5 1
12) A field soil is instrumented with tensiometers at three
depths as shown below. You wish to
know the direction of water flow (up or down) in the soil
between the measurement depths.

a. Describe (without a calculation) how you would use the
information in the diagram to
assess the direction of water flow.
b. Now use the data provided in the figure in a calculation to
determine the direction of
water flow in the soil between 15 to 40 cm depth and in the soil
between 40 to 100 cm depth.
Pair(gauge)=-310 cm
Pair(gauge)=-260 cm
Pair(gauge)=-510 cm
porous ceramic cup
capped air pocket

water filled tube
soil surface
Scale (cm)
15
40
100
0
13) A long capillary tube (radius=0.0015 cm) with a semi-
permeable membrane on the lower
end is oriented vertically and placed in a dilute sodium chloride
solution at T=20OC. If the height
of rise of water in the tube is 20 cm,
a. What is the solute potential (in head units) of the solution?
State assumptions.
b. Estimate the concentration of the sodium chloride solution.
14) Consider the following cylindrical pores. Determine the
height of rise in each configuration.
You may assume a contact angle of zero and 20 oC.

volume of 400 cm3 and a known
moisture retention function,
�(ℎ) = 0.43 �
−5
ℎ
�
0.40
If the average matric potential of the sample is -1000 cm, how
much water would you need
to add to the soil sample (assuming the water is distributed
uniformly in the soil) in order to
increase the matric potential to -100 cm?

known moisture retention function;
�(ℎ) = 0.48 �� |ℎ| ≤ 10 ��
�(ℎ) = 0.48 �10
|ℎ|
�
0.20
�� |ℎ| > 10 ��
If you have a 100 cm3 sample that is water saturated, how many
grams of water can you
remove by applying a suction of 0.40 atm?
10 cm
10 cm
r=0.01 cm
r=0.10 cm
10 cm
10 cm

r=0.01 cm
r=0.10 cm
17) Two soil samples, A and B, are placed next to each other
with good contact. Both soils are
at θ=0.25. The soil water characteristic function for each soil is
given below. Will soil
water move from one soil to the other? If so, which sample will
lose water? Briefly
explain.
Soil A: �(ℎ) = 0.55 ∗ �−18 ��
ℎ ��
�
1
3
Soil B: �(ℎ) = 0.48 ∗ �−12 ��
ℎ ��
�
1
2
18) The horse-shoe shaped soil system below contains a

homogeneous loam and is at
equilibrium. Prior to setting the horse-shoe into water as shown
below, the soil on the left
was saturated with water while the right side was oven dry.
a. Provide a qualitative sketch of the water content vs. elevation
above the water table
for the two sides of the horse-shoe. Provide a brief explanation.
b. If the divider at the top of the horse-shoe is removed, will
water move to the right?
Explain.
c. If a hole is drilled in the sidewall of the arc holding the soil,
will water drip out?
Explain.
Initially water saturated Initially air dry
10 m
water
divider
19) Consider the following soils separated by a no flow barrier.
The soils are resting in water
at equilibrium.

a. Provide a qualitative sketch of the soil water content
distribution (that is, θ vs.
distance) above the water-table in the two soils. Explain the
similarities or
differences in the sketches for the two soils.
b. Suppose that a portion of the no flow barrier at 3 m above the
water is carefully
removed allowing contact between the two soils. Will water
move from the clay to the
sand? From the sand to the clay? Explain.
20) A freely draining field soil (soil profile shown below on
left) has a uniform matric potential
of -150cm several days after a rain-storm that had saturated the
soil profile. Provide a qualitative
diagram (no calculations needed) of the relative water content
versus depth using the axes on the
right. Briefly explain your rationale.

20 m
0 m
sand clay
θv
D
e
p
t
h

Soil surface
Sandy loam (60% sand, 10% clay)
Clay loam (30% sand, 35% clay)
Loam (45% sand, 15% clay)
Sand (90% sand, 5% clay)
Equilibrium diagram problems- These examples cover the type
problems that
will appear on the exam but the actual exam problem may be
altered.
21) A sandy loam soil sample is placed on a saturated porous
plate in contact with water as
diagramed below. Determine the equilibrium matric potential
or hydrostatic pressure
(in your choice of unit systems) in the soil at point A. Would
you expect this soil to be
saturated? Why or why not.

22) The following system is at equilibrium.
a. Find the matric potential (at the midpoint) in the sand and in
the silt.
b. At equilibrium, how do you expect the water content to
compare in the two soils (circle one):
θsand = θsilt
θsand < θsilt
θsand > θsilt

Explain your reasoning.
sand silt
Pair=1.50 atm
Pair=0.90 atm
water
water saturated porous plate
air chamber
10 cm
0
70 cm
80 cm
Pair (gauge)= -200 mbar
Air chamber
Pair= 850 mbar
0.10
1.00
m

0
A∙
porous plate
water
23) The following system is at equilibrium. Find the water
pressure term (h or P) of the total soil
water potential at point A and point B. You may express your
response in either energy/volume or
energy/weight of water.

24) The following soil-water systems are at equilibrium (two
separate problems). Find the
requested information (indicated by the question mark) in each
figure. You may express your
response in either energy/weight or energy/volume of water.
a. b.
B
A

Semi-permeable
membrane
Pair=813 mbar
s=-100 cm
Not
semipermeable to
solutes
Pair=1000 mbar
1.0 m
2.0 m
3.0 m
0.5 m
sandy loam
clay loam
Saline solution
(ρ=1.0 g/cm3) Solute free
capped air pocket
Pair = ?
50cm
water table

saturated soil
rigid,
unsaturated
soil
10 cm
Pair=1 atm
porous cup
capped air pocket
rigid,
unsaturated
soil
h=?
water filled tube
Pair=-0.20 m
60 cm
water filled
tube
Pair=1 atm
25) A soil sample is placed on a saturated porous plate and then
subjected to a series of

manipulations. Determine the equilibrium matric potential at
the midpoint of the soil sample (in
your choice of unit systems) at each step in the sequence.

Step 3: Step 4:
Pair (absolute) = 0.60 atm
Semipermeable membrane
saline solution, s = -Π
60 cm
10 cm
10 cm
40 cm
20 cm
10 cm
Semipermeable
membrane
saline solution, s = -Π
Notes-
• No evaporation
• Surrounding air pressure=1 atm
• Π= 4.9 x 104 Pascal
soil
water saturated porous plate water

26) The following soil-water system is at equilibrium. Find all
the components of the soil water
potential head at locations A, B, and C.
Pair=1.15 atm
Pair= 1 atm

No evaporation
50 cm
50 cm
∙ B
C ∙
A ∙
s=-200 cm
semipermeable membrane
Porous ceramic
water
saline solution
Article Discussions
1. What are the advantages and disadvantages of incremental
internationalization? (From the article: Internationalization
Process of Fast Fashion Retailers: Evidence of H&M and Zara)
Globalization has made many businesses all over the world to
adopt strategies that will give them a competitive edge over
other similar businesses. Some of them have adopted
incremental internationalization, which refers to the behavior of
firms to start operations in domestic markets and later expand
into new markets. This helps firms to establish themselves in
local markets before venturing into new foreign markets. As
such, it makes sense for a firm to first raise capital and learn the
most efficient business operations locally before it can expand

into other countries. Another advantage of incremental
internationalization is that firms are facilitated to gather
sufficient resources that enable them to come up with effective
strategies to enter the new markets. For instance, a firm
intending to operate globally should first consider setting up
operations in a stable environment that will facilitate for its
growth and sustainability. Based on the lessons learnt, it can
then identify more effective strategies when operating in other
countries. Some may argue that the model has become outdated
due to increased competition that has forced companies to seek
ways of faster penetration into new markets. However,
incremental internationalization is an effective model for firms
intending to grow gradually.. this model is also criticized as it
encourages firms to have late market entry, which may limit
their market share as other early entrants may have already
taken over the market.
2. Why are international brands first introduced as premium
brands in developing countries?(From the article: Evolution
Patterns of Apparel Brands in Asian Countries: Propositions
From an Analysis of the Apparel Industry in Korea and India)
It makes sense to attach higher prices to products so as to earn
higher earnings. This concept has been used by many
international firms, as premium brands are associated with high
quality and well–designed products. This is due to the fact that
local apparels are regarded as being inferior in quality and
design. Therefore, premium brands fetch better prices, and the
firm earns a competitive advantage over other firms producing
domestic apparel. For instance, the Tommy Hilfiger brand is
considered as a premium brand in India, and it is so costly that
the price of one item is twice a worker’s monthly income. To
support this point, most developing countries prefer wearing
international brands to their own designs. This is due to the
mentality that global brands are more superior. However,
premium pricing is only a marketing strategy to enhance a
company’s competitive advantage.

3. Which is the best method of approaching a consumer for
retail clothing? (From the article: International Brand
Management and Strategy: Apparel Market in China)
The far end of the supply chain is the consumer, who has a big
impact on the success of an apparel business. However,
approaching consumers is one of the biggest challenges that
businesses have to go through. It would help if the were to be
aware that multiple methods of communication that are
cumulated over time are the best options for approaching
consumers. When making decisions regarding clothing items,
consumers rely on pre–existing knowledge. Various
communication sources should be used to get to the consumers
so as to enhance brand awareness. For instance, in China,
consumers for apparel do not take time to search for the best
clothing items that are available, as their basis for selecting a
particular brand is due to the attributes that have been
communicated to them via various communication channels. In
other parts of the world, this strategy can also be adopted. A
company that sends a consistent message about its brand raises
consumer awareness, therefore influencing consumer purchase
decisions.
Developing Sustainable Supply Chains
Chapter 4 Review
Going Global
By
Fatimah Hakeem
Ann Huebner
Fareeha Naz

Consumers and corporations all across the world have
demonstrated interests in social, environmental, economic,
political responsibility:
Recycling, global warming, pollution, workers conditions,
unfair treatment of human beings.
Consumers and Corporations responsibilities
The expression which gives attention to these responsibilities in
the business processes and supply chain is Codes of conduct.
but the Sustainability considered strategy to integrate these
responsibilities integrate dimensions to enhance cooperation
and uniformity among the supply chain.
Code of conduct = supporting sustainability
Concepts related to responsibilities
Small firms = applying a code of conduct always is so difficult.
Challenges: multiple languages, resource availability, and
limitation of infrastructure and financial.
Challenges of sustainability of corporate supply chains

Activist organizations by consumer worldwide has helped shape
working conditions
e.g. The Gap store: agreed implement in workers conditions.
pressure for corporate attention to sustainability
Corporate exploitation:
law price wages, workplace sexual harassment, extended work
hours, child labor.
Outcome: FLA
To mission is to improve work locations worldwide.
corporation membership in the Fair Labor Association.
e.g Adidas and Nordstrom.
implementation of corporate supply chain sustainability

Worldwide Responsible Accredited Production.
WRAP process:
Application > Self-Assessment > Monitoring > Evolution >
Certification
WRAP
Corporate Codes of Conduct
WRAP
Application
Self-Assessment
Monitoring
Evaluation
Certification
Fair Trade
Fair Trade (Cont'd)
Organizations
WFTO
FLO
IFAT

Factors:
Ethics
Morals
Human Rights
Abuses in Apparel Industry
Three primary factors that contribute to human rights
violations:
Poverty
Gender
Age
therainseason.com%2F2012%2F11%2F28%2Ffree2work%2F&p
sig=AFQjCNHoEf6gD5cgCyGJkojrLqIOx-
MGRA&ust=1442254142887547

Poverty Measurement
HDI- Human Development Index considers three variables:
GDP per capita
Life expectancy at birth
Adult literacy
Human Rights
Abuses in Apparel Industry
www.independent.org%2Fpublications%2Fworking_papers%2Fa
rticle.asp%3Fid%3D1369&
Human Rights

http://www.srilankabrands.com/made-in-sri-lanka-with-pride-
and-integrity/
Many consumer activist groups now demand:
-that all workers need to be paid a living wage.
Human Rights Organizations
ttp://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=ima
ges&cd=&cad=rja&uact=8&ved=0CAUQjhxqFQoTCIDDo9G19
McCFYeZgAodJhIFZg&url=http%3A%2F%2Fen.maquilasolidar
ity.org%2Fcurrentcampaigns%2FBangladesh&psig=AFQjCNGM
k0324vwUFx2Zxn-PdVkt2AHQWA&ust=1442247603012273
Trade Unions
10 months after the Rana Plaza building collapse in Bangladesh

killed over 1,100 garment workers and injured over 2,000 more,
70 trade unions protested working conditions
Support education
Prevent pollution
Value biodiversity
Promote safety and health
Minimize energy consumption
Preserve natural resources
Recycle waste
Provide reasonable wages
Support equal opportunity
Commit to community
Make a profit
THE SPHERES OF SUSTAINABILITY
Going Global Textbook , pg 111
Discussion Question:
How does this illustration guide the apparel industry toward a
sustainable supply chain?
Ethical Fashion Dimensions: Pictorial and Auditory Depictions
Through Three Culture Perspectives

The article is an explanatory study comparing the attitudes of
young fashion conscious consumers towards ethical fashion in
Canada, France and the United Kingdom. The study includes
cross cultural research done by the methods of forming focus
groups, interviewing students from universities, and analysis of
mood boards created by interviewees. Due to fast fashion
manufacturing costs have been lowered and the increased
pressure by consumer demand for cheaper fashion items has led
to sacrificing of ethical standards so that they can remain
competitive in the fashion industry.
Although awareness of ethical issues has increased and the
consumers are sympathetic towards the ethical issues but the
visual appearance of the garment strongly influences the
purchasing intention of the garment as opposed to its ethical
credentials. This article will help address the gap by actually
providing results of the research which compare the attitudes
towards ethical fashion of apparel consumers in these three
countries.
The findings show that the consumers of UK generally thought
that ethical clothing would be expensive however Canadians
didn’t think the same, they thought ethical clothing would be
less available. The Canadians didn’t want to pay an extra price
for the garment being ethical while French consumers were
willing to pay and extra price if it fulfilled as a redemption for
other bad behavior. Some consumers mentioned that if the other
important criteria was met by the garment they would be willing
to purchase an ethical garment while some were confused about
the meaning of ethical fashion thus were uninterested in buying
it at all. While some people thought of ethical garments as
“dull” or “boring” the others said they would boycott a company
if they were made aware of its unethical practices.
The article also has some limitations and scope for further
research. As the participants of the study were a small group of

homogeneous people who were in the same age bracket ( 18-26)
and broadly belonging to the same socio-economic and
educational backgrounds, the information derived may not be a
very good representative of the diverse market of that county.
Also the cross cultural nature of the research required to
translate data from French to English which might not be as
accurate as thought.
Phau, I., Teah, M., & Chuah, J. (2015), Consumer attitudes
towards luxury fashion apparel made in sweatshops, Journal of
Fashion Marketing and Management, 19 (2), 169-187.
The motivation of this study is to let more people have more
understanding on how consumer attitudes play a significant role
in luxury fashion apparel which was made in sweatshops in the
developing countries. And also can use the hypothesis extension
to population, not only in Australia, but also for other countries
of different socioeconomic groups which may produce different
results.
The benefits are high profits and low price for production.
This article reports that only 1% of apparel production
practices “ethically made apparel” of the 1 trillion global
fashion industry. This means that there is a huge sustainability
problem in the fashion industry that needs to be addressed.
Also, the increasing apparel consumer demands also increase
the demand for consumer information for ethical manufacturing
practices from fashion companies. This make more people
recognized that ethical branding strategy should be utilized in
the future to maintain sustainable development in the society.
The framework used in this article was Theory of Planned
Behavior (TPB), to examine consumers’ attitudes towards

luxury fashion apparel brands made in sweatshops.
In this quantitative article, the authors gathered data by
conducting a “mall intercept” self-administered questionnaire.
They did this by preparing the interviewer and approaching
every fifth person who passed by the mall entrance. The data
collection was over a period of three weeks, both during
weekdays and weekends. Out of 260 questionnaires, 63 were
incomplete and eliminated and only 197 were used for analysis
using SPSS software. % were male, 51% were female and the
majority of respondents were ages 21-35, with earnings less
than $15,000/yr.
The survey instrument used was a seven-point Likert Scale
to measure and analyze how attitudes(3 dimensional), social
norms (3 dimensional), and perceived behavioral control- 1
dimensional (PBC) affect “intention not to purchase luxury
branded apparel made in sweatshops” and how significant it is
towards “Willingness to pay more for luxury branded apparel
not made in sweatshops”.
From all 17 Hypothesis, eight were found supported (H1b,
H3b, H3a, H2a, H6b, H8a, H8b, and H9) and 9 were not
supported (H1a, H2b, H4a, H5a, H6a, H7a, H4b, H5b, and H7b).
After looking over the 17 hypothesis, some of the practical
implications of this article may be that consumers who are
aware of luxury brands who use sweatshops are willing pay a
higher price for luxury items not made in sweatshops. This can
lead to luxury brands having an option to implement “super-
premium” prices and also may be able to create an
“exclusiveness” of the luxury brand and strategically create a
niche-market.
The limitations of this study could be that the sample
population was too small, authors could have gathered more

data by staying longer than 3 weeks, or by not waiting until the
fifth person to walk in through the doors. The sample was not
representative of the general population because the majority of
respondents were probably not aware of the issue at hand (Phau
et al, 2014).
Problem Set #2
SCOR470 Fall 2015
Topics: Soil water potential, unit conversions, soil water
content
Honor code opportunity- It is required that the work you are
turning in is your effort. In addition,
you may wish to sign the honor code statement. Declining to
sign this statement will not count
against you.
"I have not given, received, or used any unauthorized
assistance."
Signature
1. Unit conversions
a. You are curious about the matric potential of an air-dried

soil. This depends on the
relative humidity of the air of course but you find a value of -
2.20 x 105 J/Kg in a journal
article. Express this in MPa and m. (Note that the permanent
wilting point for plants is
typically assumed to be -1.5 MPa.)
b. You need a value for the osmotic pressure of maple tree sap
and find a table in a
reliable older reference stating 2.23 x 106 erg/cm3. Convert this
to m, ft., and Pa.
c. Your grandfather’s WWII submarine could withstand about
1.5 MPa of water
pressure. Assuming a saltwater density of 1.03 g/cm3, calculate
the crush-depth of the
submarine in m and ft.
2. a. Calculate the energy/volume (in J/m3) of water a plant
root must overcome to withdraw
water laterally from a soil with a matric potential of -15000 cm
with an EC of 8 dS/m.
b. Assuming 15 oC, calculate the relative humidity in the soil
air for the soil in part (a).
Note that this soil is near the wilting point for many plants.
Helpful information: The EC, electrical conductivity, is a
measure of the total dissolved salts in a

system. For a wide range of soils, the following empirical
relationship relates the EC of the soil
solution to the osmotic pressure (Π) of the solution; Π(bars)=
0.36 x EC (dS/m). The EC unit is
decisiemen per meter.
3. Consider a soil profile above a shallow water table:
clay loam
water table
loamy sand
loam
silt loam
0.40 m
0.30 m

0.15 m
0.20 m
Soil surface
Suppose the θ(h) in this profile is described by the Brooks-
Corey formulation:
θ(h) = θS for |h| ≤ |he|
θ(h) = (θS -θr)[(he/h)
λ] + θr for |h| > |he|
Using the parameters in the following table, calculate and plot
the equilibrium water content
profile, θ(z), from the soil surface to the water table.

4. The following system is at equilibrium. Determine each
component of the total soil water
potential in energy/volume and energy/weight at the points
indicated (A, B, …). If a component
is zero, state why.

Soil
θS
θr
|he|
(cm)
λ
Silt Loam
0.49
0.10
12
0.21
Loamy sand
0.40

0.02
3
0.47
Loam
0.44
0.05
7
0.23
Clay loam
0.51
0.14
19

0.18
Loamy
sand Clay loam
A∙ B∙
Semi-permeable
membrane
Soils slightly saline
EC=0.75 dS/m
Pair(absolute)=
0.90 atm
15 cm
40 cm
60 cm
5cm
0.05 M KCl
Pair=1.0 atm
T=25 oC
No evaporation
M is moles/liter
Liquid saturated porous

plate
5. Refer to Problem# 4.
a. Consider a microorganism at point A in the loamy sand.
Assuming the cell wall of the
microorganism is semipermeable, what osmotic (solute)
potential is necessary within the cell
to avoid loss of cellular fluid to the soil water? You may
assume that osmotic adjustment of
the cellular fluid is the only defense against lower water
potentials outside of the cell.
b. Using the θ(h) parameters for the soils listed in Problem 3,
calculate the water content at
Point A and Point B in the figure.
c. Suppose the microorganism at point A has had enough of
fighting the water robbing forces
in her loamy sand home and dreams of moving to a wetter
environment. Her life coach
recommends she follow her dreams so she packs up and moves
to the wetter soil(?) at
position B (the clay loam). What cellular solute potential is
necessary to prevent
dehydration in the new home?
6. A common representation of the moisture retention function

first used by van Genuchten
(1980) is as follows:
θ(h) = (θS−θr)[1+(α|h|)n]m + θr where m = (1-
1/n)
where h(cm) is the soil water pressure head (matric potential in
head units), θs is the saturated
water content, θr is the so-called residual water content, and α
(cm-1) & n are shape parameters.
The purpose of this problem is to give you practice working
with and interpreting this function.
Consider the following soils with their typical parameter values
(based on texture);
Soil Texture θs θr α(cm
-1) n
sandy loam 0.39 0.03 0.070 1.60
silt loam 0.44 0.07 0.025 1.35
clay 0.55 0.12 0.010 1.20
a. For 0.1<|h|<50000 cm, plot θ(h) for each soil in the table. I
recommend that you use a log
scale for h.
b. If water is available for plant uptake over the matric potential
range of -0.0100 to -1.500
MPa, calculate the cm of plant available water (PAW) in a 60
cm deep root-zone of each
texture.

c. If you allow a crop to deplete 60% of PAW prior to
irrigating, estimate the time between
irrigations in each of the soils if the evapotranspiration loss is
0.7 cm/day. You may ignore soil
water drainage below 60 cm depth and assume no rainfall.
d. Suppose the sandy loam is at θ=0.100, the silt loam is at
θ=0.150, and the clay is at
θ=0.350. Samples of each soil are then placed in horizontal
contact;
Upon contact, what is the direction of flow between the layers?
Explain.
Sandy
loam
Silt
loam
Clay
7. Tensiometers are used to measure matric potential (soil water
pressure) and thus can be helpful
in determining the direction of water flow and estimating soil
water content if θ(h) is known for the
soil. The three tensiometers shown here are in the silt loam and
clay soils of problem # 6.

Readings (the gauge pressure of the air in the headspace) are
reported for three dates during the
early summer:
Tensiometer 1 Tensiometer 2 Tensiometer 3
June 1 -80 cm -110 cm -150 cm
June 15 -240 cm -200 cm -300 cm
June 30 -450 cm -400 cm -350 cm

a. For the three dates, calculate the water content at each depth
and sketch the water content profile
between 20 and 60 cm depth.
b. For each date, determine the total soil water potential at each
depth and then indicate the
direction of water flow between 20 and 40 cm depth and
between 40 and 60 cm depth. Note that
you can assume that the tensiometer is at equilibrium with the
soil water.
Water saturated
porous cup
Water filled
tube
Sealed
headspace #1 #2 #3
Silt Loam
Clay
20 cm
40 cm
60 cm
10 cm

Exam 1 Test questions- At least 90 of the points on your exam.docx

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