Q6. Which of the following cause soil salinisation? (0.5 mark)

(a)  Lots of rainfall and low temperature.

(b) Excessive evapo-transpiration.

(c)  Native pasture land use.

(d) Good soil drainage.

Correct Answer (b)

Q7. Which of the following statements is not true? (0.5 mark)

(a) Granite is a felsic rock that is rich in feldspars and quartz.

(b) Ferro-magnesian minerals are abundant in felsic or acidic rocks.

(c)  Muscovite and biotite are primary minerals.

(d) Sedimentary rocks are the most common rocks that cover ~75% area exposed on the Earth’s surface.

Correct Answer (b)

Q8. Micas and orthoclase feldspar are primary minerals that are important in the supply of − (0.5 mark)

(a) nitrogen in soils.

(b) potassium and phosphorus in soils.

(c)  potassium in soils.

(d) nitrogen and potassium in soils.

Correct Answer (c)

Q9. Which of the following chemical weathering reactions shows feldspar weathers to produce kaolinite? (0.5 mark)

(a) CaCO3  + H2CO3 → Ca2+  + 2HCO3-

(b) FeS2  + 3.75O2  + 2.5H2O → FeOOH + 2H2SO4

(c)  Fe2SiO4 + 2H2O + ½ O2 → Fe2O3  + H4SiO4

(d) 2KAlSi3O8  + 2H2CO3  + 9H2O → 2K+  + Al2Si2O5(OH)4  + 2HCO3-  + 4H4SiO4

Correct Answer (d)

Q10. Which of the following elements are highly enriched in the soil compared to the Earth’s crust? (0.5 mark)

(a) Si and C

(b) C and Al

(c)  C and N

(d) N and Al

Correct Answer (c)

Q11. The cation exchange capacity of the soil is expressed in the units − (0.5 mark)

(a) µS kg- 1.

(b) mg kg- 1.

(c)  mS kg- 1.

(d) mmolc kg- 1.

Correct Answer (d)

Q12. Which of the following conditions can cause a soil to be hydrophobic? (0.5 mark)

(a) Continuous application of N fertilizer to clay soils.

(b) Continuous flooding of clayey soils.

(c) Continuous tillage of sandy soils.

(d) Wax-like substances from organic matter that coat the sand particles.

Correct Answer (d)

Q13. Generally, it is accepted that a plant cannot grow well if the air-filled porosity in the soil is less than 10% because- (0.5 mark)

(a) The soil is too loose and roots cannot anchor on it.

(b) Soil pH becomes acidic at that condition.

(c)  Oxygen cannot diffuse adequately in soil pores.

(d)  Plant nutrients will not be available under that condition.

Correct Answer (c)

Q14. A rice growing field near Griffith has a crop water use index (CWUI) of 8.5 kg/ha/mm in producing rice. While a sorghum field near Moree has a CWUI of 4.0 kg/ha/mm. Which of the following statements is most correct? ( 1.0 mark)

(a) The two numbers cannot be directly compared as CWUI does not consider how much water is applied and lost.

(b) The sorghum field near Moree is more water-efficient in producing grain.

(c)  The rice field near Griffith is more water-efficient in producing grain.

(d)  Rice crop uses less water than barley.

Correct Answer (a)

Q15. Which of the following soil has the largest saturated hydraulic conductivity? (1.0 mark)

(a) A horizon of a clayey Vertosol.

(b) Sodic B horizon of a Sodosol.

(c)  Coarse sand of a Podosol.

(d) Dense B horizon from a Chromosol.

Correct Answer (c)

Q16. A soil has a volumetric water content of 30%, which is equivalent to? (1.0 mark)

(a) 0.30 mm/m

(b) 0.30 mm/m

(c) 30 m3/m3

(d) 300 mm/m

Correct Answer (d)

Q17. Which of the following practices can NOT increase the soil’s water holding capacity? ( 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.

Correct Answer (d)

Q18. A soil has a bulk density of 1.2 g/cm3, what is its volume fraction of solid (proportion of solid) assuming the density of soils is 2.65 g/cm3. ( 1.0 mark)

Q20.  The flow duration curve describes the relationship between stream flow volumes (or heights) and the probability based on historical data. This can be used to: (1.0 mark)

a)   Determine how high the water will rise in a flood event.

b)   Identify how floods will change due to climate change.

c)   Explain the relationship between river water height and streamflow volume.

d)  Ascertain the probability of a flood of a certain volume occurring in a given year.

Correct Answer (d)

Q21. Comparing the full Penman Monteith and the Priestley Taylor equation can be used to estimate actual evapotranspiration (ET) for large areas (greater than 1 km2) because: (1.0 mark)

a)  There are often only temperature data available for large areas.

b)  The Priestley Taylor is better for extimating areas of open water within an area.

c)   In the case of large areas, we can ignore aerodynamic resistance.

d)  The Priestley Taylor equations takes into account plant characteristics such as for agricultural fields.

Correct Answer (c)

Q22. The combination of high flow variability, low runoff coefficient, and high evaporation means that in Australia: Choose the best answer from the four options given below. (1.0 mark)

a)   Large storage dams are an effective way to prevent flooding and provide irrigations water.

b)   Storage dams can only be used Northern Australia.

c)   Current dams in Australia are too small to capture sufficient water for irrigation.

d)   Large dams are unreliable for storage as the flow is too irregular, evaporation too high and fill too slowly due to low runoff coefficients.

Correct Answer (d)

Q23. Green and Blue are used to designate different types of water in the landscape.

Choose a correct statement from the followings: (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

Correct Answer (a)

Q24. Riparian zones are really important for maintaining healthy river systems. One of the reasons why riparian zones are effective for managing nutrient contamination is: (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

Correct Answer (b)

Q25. The relationship between stream flow and contaminant concentration is important because it allows: (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.

Correct Answer (a)

Section B: Short answer questions, with some questions require calculations. Answer all questions in this section.

Q26. List one carbon and one nitrogen containing gas that can be emitted into the atmosphere from soil. For each gas, briefly describe the process of how it is produced, and under which conditions it is most likely to be formed. (2 marks)

Q27. Describe two natural pathways by which nitrogen enters the soil. (2 marks)

Q28. Explain why legumes (more so than non-legumes) would benefit from having a symbiotic relationship with arbuscular mycorrhiza.   (2 marks)

Q29. Explain the origin of permanent charge in phyllosilicate minerals in soils by using an appropriate example. (2 marks)

Q30. Explain the process of inner-sphere complexation in soils and describe its main features or characteristics. (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.

(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)

Q33. The following table has data for a Vertosol (clay soil) near Coonamble in NSW.

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 1.32 (g/cm3) and field capacity at 0.43 (mm/mm). Would the air-filled porosity of the soil at field capacity be limiting for plant growth and explain why? (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)

Q36. Explain how maintaining good soil structure can benefit soil’s function in water storing, filtering and mitigating drought. (2.0 marks)