Page 1 of 11
CONFIDENTIAL EXAM PAPER
This paper is not to be removed from the exam venue
Life and Environmental Sciences
EXAMINATION
SOIL2005 Soil and Water: Earth's Life Support
Systems
EXAM WRITING TIME: 2 hours
READING TIME:10 minutes
EXAM
CONDITIONS:
This is a CLOSED book exam - no material permitted
MATERIALS PERMITTED IN THE EXAM VENUE:
(No electronic aids are permitted e.g. laptops, phones)
Cal
culator - non-programmable
MATERIALS TO BE SUPPLIED TO STUDENTS:
Blank scratch paper (student will be provided with answer booklet)
INSTRUCTIONS TO STUDENTS:
Please tick the box to confirm that your examination paper is complete.
Room Number ________
Seat Number ________
Student Number |__|__|__|__|__|__|__|__|__|
ANONYMOUSLY MARKED
(Please do not write your name on this exam paper)
For Examiner Use Only
Q Mark
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Total ________
Specimen
exam-paper
Page 2 of 11
Section A: Multiple choice questions, answer all questions in this section.
Q1. W
hich of the following microorganisms do not live in symbiosis with plants (one answer
only)? (0.5 mark)
(a)Rhizobia bacteria
(b)Actinomycetes
(c)Nitrosomonas bacteria
(d)Ectomycorrhiza
Q2. Which of the following organisms are not heterotrophs (one answer only)?
(0.5 mark)
(a) Cyanobacteria
(b)Nematodes
(c)White rot fungi
(d)Mycorrhiza
Q3. Which of the following statements is true (one answer only)? (0.5 mark)
(
a)Biochar is made by burning organic matter under high oxygen conditions.
(b) An increase in lignin content in litter would increase the decay constant of this litter.
(c)Biochar would have a greater decay constant compared to the organic matter it was
made of.
(d)Soils with a low microbial carbon use efficiency have a greater potential to respire mor
e
C
O
2
than soils with a high microbial carbon use efficiency.
Q4. Which of the following statements is true (one answer only)? (0.5 mark)
(
a)Agriculture currently uses ~12 % of the world’s land surface for crop production,
and accounts for 70 % of all water withdrawn from terrestrial freshwater
resources.
(b)Europe has the highest consumption of fresh water in the agriculture sector among
all the continents.
(c)With increasing global population since 1900, the water usage in the agriculture
sector has declined.
(d)In Australia 10% of the total land area is used for crop production.
Q
5. When water freezes and thaws in cracks and fissures of rocks, thereby splitting rocks
into smaller pieces, this is an example of – (one answer only) (0.5 mark)
(a)Chemical weathering.
(b)Mechanical or physical weathering.
(c)Biological weathering.
(d)All of the above.
Q6. Which of the following does not cause soil salinisation? (choose one answer)
(0.5 mark)
(a)Lack of water.
(b)Excessive evapo-transpiration.
(c)Nutrient uptake by crop plants.
(d)Poor drainage.
Specimen
exam-paper
Page 3 of 11
Q7. Which of the following statements is true (one answer only)? (0.5 mark)
(a)Granite is a mafic rock that is rich in olivine and pyroxene minerals.
(b)Ferro-magnesian minerals are abundant in mafic and ultra-mafic rocks.
(c)Muscovite and biotite are secondary minerals.
(d)Sedimentary rocks are the most common rocks that cover ~75% area exposed on
the Earth’s surface.
Q8. Micas are primary minerals that are important in the supply of − (one answer only)
(0.5 mark)
(a)nitrogen in soils.
(b)potassium and phosphorus in soils.
(c)potassium in soils.
(d)nitrogen and potassium in soils.
Q9. Which of the following chemical weathering reactions shows feldspar weathers to
produce kaolinite (one answer only)? (0.5 mark)
(a)CaCO
3
+ H
2
CO
3
→ Ca
2+
+ 2HCO
3
-
(
b)FeS
2
+ 3.75O
2
+ 2.5H
2
O → FeOOH + 2H
2
SO
4
(c) CaAl
2
Si
2
O
8
+ H
2
CO
3
+ ½O
2
→ Al
2
Si
2
O
5
(OH)
4
+ Ca
2+
+ CO
3
2-
(d)2KAlSi
3
O
8
+ 2H
2
CO
3
+ 9H
2
O → 2K
+
+ Al
2
Si
2
O
5
(OH)
4
+ 2HCO
3
-
+ 4H
4
SiO
4
Q
10. Which of the following elements are highly enriched in the soil compared to the
Earth’s crust (one answer only)? (0.5 mark)
(a)Si and C
(b)C and Al
(c)C and N
(d)N and Al
Q11. The cation exchange capacity of the soil is expressed in the units −
(one answer only) (0.5 mark)
(a)μS kg
-1
.
(b)mg kg
-1
.
(c)mS kg
-1
.
(d)mmol
c
kg
-1
.
Q12. Which of the following conditions can cause a soil to be hydrophobic (one answer
only)? (0.5 mark)
(a) Continuous application of N fertilizer to clay soils.
(b) Continuous flooding of loamy soils.
(c) Continuous tillage of sandy soils.
(d)Wax-like substances from organic matter that coat the sand particles.
Q13. Generally, it is accepted that a plant cannot grow well if the air-filled porosity in the
soil is less than 10% because - (one answer only)
(0.5 mark)
(
a)The soil is too loose and roots cannot anchor on it.
(b)Soil could not retain enough water at that condition.
(c)Oxygen cannot diffuse adequately in soil pores.
(d)Plant nutrients will not be available under that condition.
Specimen
exam-paper
Page 4 of 11
Q14. With climate change, crop water use efficiency is going to impacted. Which of the
following practices that would be most effective in increasing crop water use efficiency
(one answer only)? ( 1.0 mark)
(a)Increasing soil temperature to enhance evaporation.
(b)Crop residue management and mulching.
(c)Reducing the use of synthetic fertiliser.
(d)Promoting the use of flood irrigation.
Q15. Which of the following soil has the smallest saturated hydraulic conductivity (one
answer only)? (1.0 mark)
(a)A horizon of a clayey Vertosol.
(b)Sodic B horizon of a Sodosol.
(c)Coarse sand of a Podosol.
(d)The surface of an organic soil.
Q16. A soil has a volumetric water content of 25%, which is equivalent to – (one answer
only)? (1.0 mark)
(a) 0.25 cm/m
(b)250 mm/m
(c)25 m
3
/m
3
(d)2500 mm
Q17. Which of the following practices can NOT increase the soil’s water holding capacity
(one answer only)? (1.0 mark)
(a)Ploughing the soil.
(b)Adding clay to sandy soils.
(c)Adding compost to the soil.
(d)Driving a tractor across a field.
Q
18. According to the soil water balance equation, evapotranspiration of a field over a
period is a function of – (one answer only) (1.0 mark)
(a)Water gains through precipitation balanced by soil water change and irrigation.
(b)Water loss through runoff and drainage downwards into the groundwater
balanced by precipitation and irrigation.
(c)Water gains via precipitation and irrigation minus water losses via runoff,
drainage, and soil moisture change.
(d)Water loss via plant uptake balanced by precipitation and irrigation.
Q
19. Which is the wettest soil condition among the listed soil water potentials (one answer
only)? (1.0 mark)
(
a)-3 J/kg
(b)-30 J/kg
(c)-300 J/kg
(d)-1500 J/kg
Specimen
exam-paper
Page 5of 11
Q20. The flow duration curve describes the relationship between stream flow volumes (or
heights) and the probability based on historical data. Which of the following could be
used as an indicator of the proportion of high flows – (one answer only). (1.0 mark)
a) Q90
b) Q50
c)Q10
d)None of the above
Q21. The Priestley Taylor equation is a simplification of the Penman Monteith equation
and can be used to estimate actual evapotranspiration (ET) for large areas (greater than
1 km
2
) because – (one answer only). (1.0 mark)
a)It ignores the effect of irrigation.
b)It incorporates the effect of wind reducing the humidity in the air.
c)In the case of large areas, we can ignore aerodynamic resistance.
d)In the case of large areas, temperature is less important than radiation.
Q22. Australia’s streamflow characteristics are considered unique. What are the main
characteristics that make the streamflow unique according to the paper by McMahon et al
(2007), which we discussed in class. (one answer only). (1.0 mark)
a)Australia has the lowest runoff compared to all other continents.
b)Australia’s streamflow occurs only in the colder seasons (winter/spring).
c)Australia has the lowest runoff coefficients and highest variability compared to all
other continents.
d)Australia floods more regular than any other continent.
Q23. Green and Blue are used to designate different types of water in the landscape.
Choose a correct statement from the followings – (one answer only). (1.0 mark)
a)Green water consists of all water used by vegetation and water stored in the soil.
b)Blue water consists of all water used by vegetation and water stored in the soil.
c)Water evaporated by an irrigated crop is Blue Water.
d)Water contaminated with green algae is Green Water.
Q24. In the framework of source, mobilisation and delivery for water quality, riparian
zones can play an important role in the delivery – (one answer only). (1.0 mark)
a)Because the vegetation in riparian zones evaporates water with high nutrient
concentrations, which filters the water moving into the stream.
b)Because the vegetation in riparian zones slows the water flow moving into the
stream, allowing part of it to infiltrate and biological processes to reduce
contaminants.
c)Because the vegetation in riparian zones stops water from moving into the stream.
d)Because the vegetation in riparian zones is more healthy than other parts of the
catchment.
Q25. The relationship between stream flow and contaminant concentration is important
because it allows– (one answer only). (1.0 mark)
a)Estimation of the total load of a contaminant and its possible source flow path.
b)Accurate prediction of the origin of the contaminant.
c)Linking the contaminant to evaporation processes.
d)Accurate prediction of the flow volumes in a stream.
Specimen
exam-paper
Page 6 of 11
Section B: Short answer questions, with some questions require calculations. Answer
all questions in this section.
Q26. Describe three strategies by which plants can increase phosphorus uptake from soil.
(2 marks)
Q27. The table below shows properties for soil A and soil B:
Soil Sand (%) Silt (%) Clay (%) Microbial carbon use
efficiency
A 50 20 30 0.7
B 72 20 8 0.3
Based on these properties, which soil would you expect to have a greater potential for
stabilising soil carbon? Explain why. (2 marks)
Q28.
Describe two abiotic processes that result in reduced ammonium concentration in the
soil. Describe under what soil conditions these abiotic processes particularly could occur.
(2 marks)
Q
29. Explain the origin of variable charge in kaolinite or goethite in soils by using an
appropriate example. (2 marks)
Specimen
exam-paper
Page 7 of 11
Q30. Describe the main features or characteristics of outer-sphere complexation in soils,
also give an example of a cation or an anion adsorbed by this process or mechanism.
(2 marks)
Q31. Briefly describe the effects of acidification in the soil. (2 marks)
Q32. Consider the following laboratory data for a surface soil (0-10 cm) to answer the
following questions.
Soil property Value
Organic carbon (%) 1.5
Bulk density (Mg/m
3
) 1.40
Ca (mmol kg
-1
) 40.0
Mg (mmol kg
-1
) 1.0
Na (mmol kg
-1
) 4.5
K (mmol kg
-1
) 4.0
(i) Calculate the exchangeable sodium percentage (ESP) of the soil. Is this a sodic soil or
not? (1.0 mark)
(ii) Calculate the quantity (in tonnes or Megagrams) of organic carbon that is present in the
top 10 cm of the soil in one hectare. (1.5 marks)
Specimen
exam-paper
Page 8 of 11
Q33. The following table has data for a Vertosol (clay soil) near Narrabri in NSW.
Depth (mm)
Bulk density
(g/cm
3
) Soil texture
Field
Capacity
mm/mm
Wilting Point
mm/mm
0-2501.27 Medium Clay 0.43 0.20
250-6001.35 Medium Clay 0.37 0.25
600-10001.45 Heavy Clay 0.36 0.24
Calculate the Profile Available Water capacity (0-1 m). Is the calculated value small,
medium or large? (2.5 marks)
Q34. A Vertosol has a bulk density of 1.35 (g/cm
3
) and field capacity at 0.37 (mm/mm).
Assuming the density of solid is 2.65 g/cm
3
, what is the soil’s the air-filled porosity at field
capacity, and would it be limiting for plant growth and explain why? (remember Φa+ ΦL +
Φg =1, Φs = ρ/ ρs) (1.0 mark)
Q35. A topsoil is at a volumetric water content of 20%, and rain falls on the soil overnight.
Observation shows that the volumetric water content of the soil has increased to 25% and
the water has penetrated 200 mm in the soil. How much rain water has fallen in the soil?
(2.5 marks)
Q
36. Explain how maintaining good soil structure can benefit soil’s function in water
storing, filtering and mitigating drought. (2.0 marks)
Specimen
exam-paper
Page 9 of 11
Q37. The translation and attenuation of the flood peaks in river routing depends very
strongly on the storage in the river. In the two models of routing discussed in class (Linear
and Muskingum) storage is conceptualised differently. Explain:
(a)The difference in conceptualisation of storage in the two models (no maths or
equations needed, describe how the concepts are different). (2.5 marks)
(b)How storage influences the flood peak, for example compare the change in a
flood peak in a river with lots of storage and a river with very little storage as the
flood peak travels downstream? (2.5 marks)
Specimen
exam-paper
Page 10 of 11
Q38. The hydrograph represents the flow in a stream as a function of time. Outline how
changes (for example increases) in the following two processes would change the shape of
the hydrograph:
(a)Change in Hortonian runoff.(2.0 marks)
(
b)Change in groundwater recharge.(2 .0 marks)
Specimen
exam-paper
Page 11 of 11
END OF EXAMINATION
Specimen
exam-paper
