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SSA520S - SOIL SCIENCE - 2ND OPP - JAN 2023 |
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(
nAm I BIA un IVERSITY
OF SCIEnCE Ano TECHn OLOGY
FACULTYOF HEALTH,NATURAL RESOURCESAND APPLIEDSCIENCES
DEPARTMENT OF AGRICULTUREAND NATURAL RESOURCESSCIENCES
QUALIFICATION: BACHELOROF SCIENCEIN AGRICULTURE& BACHELOROF HORTICULTURE
QUALIFICATION CODE
07BAGA, 07BHOR
COURSECODE: SSA520S
COURSENAME: Soil Science
NQF LEVEL: 5
SESSION:
DC::.-.:.TION:3 Hours
NQF CREDITS: 12
January 2023
MARKS: 100
SUPPLEMENTARY EXAMINATION QUESTION PAPER
EX~;MINER{S} Mr Brian J. Mhango
MODERATOR: Dr T. Nzuma
INSTRUCTIONS
1. Answer ALL the questions.
2. Write clearly and neatly.
3. Number the answers clearly.
PERMISSIBLEMATERIALS
1. Examination question paper
2. Answering book
3. Scientific calculator
THIS QU!EST!ONPAPERCONSISTSOF 4 PAGES{Excluding this front page)
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r
ANSWER ALLTHE QUESTIONS
QUESTION 1
a) The ___
is a vertical section through soil mass
A. Soil erosion
B. Soil profile
C. Both A and B
D. None of the above
b) Wind erosion is common in
A. Humid zones
B. Arid zones
C. Arid and semi-arid zones
D. Arid and Humid zones
c) Wind erosion is more in
A. Cohesive soil
B. Non-cohesive soil
C. Rocky soil
D. All of the above
d) The reason for wanting to organize soil knowledge is the basis for:
A. The principle of prioritization
B. The principle of classification
C. The principle of purpose
D. The principle of identity
e) The mass of dry soil is 380 grams, if the particle density is 38g/cm 3 then:
A. The soil bulk density is> 39g/cm 3
B. The soil bulk density is< 38 g/cm 3
C. The soil bulk density is about 39g/cm 3
D. The soil bulk density is unknown
[10)
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QUESTION 2
As may be applicable, determine the % sand, %silt, %clay or the soil texture name in the tables
below:
%Clay
30
60
10
45
5
e0
%Sand
10
30
40
10
35
% Silt
60
10
40
45
Soil Texture Name
Silt Clay loam
Loamy Sand
10
[20]
Question 3
The table below shows the Unified Soil Classification System (USCS),a soil classification system used
in engineering and geology to describe the texture and grain size of a soil.
First and/or Second Letters
Letter
Definition
G
Gravel
s
Sand
M
Si!t
C
Clay
0
Organic
Letter
p
w
H
L
Second Letter
Definition
Poorly graded (uniform particle sizes)
Well-graded (diversified particles sizes)
High plasticity
Low plasticity
Provide symbols for the following descriptions based on this classification system:
a) Well-graded gravel with silt
b) Poorly graded sand with silt
c) Well-graded organic clay
d) Organic clay with silt
e) Well-graded sand with silt
(10}
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QUESTION 4
4.1 Excluding the human factor, name the five factors of soil formation
(5)
4.2 What is nitrogen fixation and why is it important?
(5)
4.3 According to the three principles of soil classification, explain what is meant by "Organization"?
{20)
[30)
QUESTION 5
5.1 Discuss in detail the erosion processes proposed by Hjulstrom between water speed (cm/sec)
and particle diameter (mm).
(15)
2.2 Draw a diagram showing how rainfall erosivity and soil erodibility factors contribute to soil's
Susceptibility to water erosion
(15)
[30)
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SOIL TEXTURE TRIANGLE
THE END
TOTALMARKS:100
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