Ag Hort Science 2.2
Student exemplar
Structure of response
Task: Question 1
(order & arrangement of
ideas/ concepts)
A dairy farmer has purchased a property where there is a high rainfall and a clay loam soil type. The property is
susceptible to water-logging, especially during the winter. To ensure that this land is suitable for pasture production,
it will require some subsurface drainage.
(a)
(i)
State THREE physical features of a clay loam soil.
(ii)
Describe how a subsurface drainage system modifies the physical factors of a clay loam soil.
Small pore spaces, Small particles, High water-holding capacity
Language Features
Technical Features
(subject and topic
specific words &
symbols)
Subsurface drainage drains away the excess water not needed in the soil, this increases the amount of air (O2 ) in the soil which
increases respiration rates and also increases the temperatures of the soil, increasing chemical reaction rates.
Key Ideas/Features
(factual/ objective, focus
on things & processes;
impersonal style)
Style
(impersonal, passive
voice, attention on action,
not who did it)
(b)
Explain how subsurface drainage increases the quality of the pasture.
(c)
Evaluate the economic reasons why a dairy farmer would use a subsurface drainage system
instead of a surface drainage system to reduce water-logging in their pasture.
Subsurface drainage drains away the excess water so the soil is not saturated. With the excess water drained there is more air (O2 )
in the soil for respiration rates to increase. If the soil was saturated the temperature will be very low, so with the excess water
drained and more air in the soil the soil temperature will increase along with the chemical reaction rate like photosynthesis, this
increases pasture quality and quantity. Also having the excess water drained will decrease the risk of pugging damage by stock and
machinery.
Subsurface drainage is expensive to install because of the machinery used to install it. But it is a more permanent option rather than
surface drainage. Once installed the subsurface drain needs little maintenance and the farmer is able to use the land above the
drain. Subsurface drains are very effective in clay loams especially. Because clay loams have high water holding capacity the
subsurface drains drain away excess water improving pasture growth and stock health.
Surface drains are effective as well, They drain away excess water improving the air concentration in the soil. But the farmer cannot
use the land that the drain takes up so there is less pasture for his stock. Also if the drain is over a certain depth it has to be fenced
off so stock are unable to harm themselves in the drains and also to stop erosion of the land and dung and urine from entering the
drain and getting into waterways. So a subsurface drain is more expensive to install but needs little maintenance also the pasture
above is in use for stock and is very effective and the better option, and create a higher financial return in the long run.
Descriptive words and
phrases (which specify
the subject and details of
the idea/ concept(s))
Connective / linking
words & phrases (which
accomplish the
explanation and/or
analysis)
Structure of response
(order & arrangement of ideas/
concepts)
Task: Question 3
New Zealand is often exposed to strong winds. Therefore, kiwifruit crops may require some form
of shelter. The use of artificial shelter rather than natural shelter is increasingly common in
kiwifruit orchards.
(a)
(i)
Describe the main difference between a natural shelter and an artificial shelter.
(ii)
Describe how a shelter carries out its main function.
Language Features
Technical Features
(subject and topic specific words
& symbols)
A natural shelter can take many years to establish and be effective where as an artificial shelter can be
established in a week and be effective straight away.
A shelter reduces the speed of the wind that is hitting the crops therefore the wind does less damage to the
crop. The shelter either natural or artificial is deigned to have small pores ( or gaps between branches) so
that wind passes through it at a reduced speed, without becoming turbulent and hitting crops(which would
cause more damage)
Key Ideas/Features
(factual/ objective, focus on
things & processes)
Style
(impersonal, passive voice,
attention on action, not who did it)
(b)
Explain how any shelter improves the timing of harvesting kiwifruit crops.
(c)
Evaluate the environmental AND social reasons why a kiwifruit grower would use artificial
shelter over natural shelter to improve the timing of the harvesting of kiwifruit.
A shelter provides uniform protection for the crop so that all the crops are exposed to a reduced wind. This
means that less or all damage to plants is reduced. Therefore plants use the energy created during
photosynthesis in growth rather than in repair. The increase in energy avalible for growth means that fruit
will be able to develop faster.
Descriptive words and
phrases
(which specify the subject and
details of the idea/ concept(s))
If the kiwifruit orchard was next to a residential area a natural shelter may cause leaves to fall into
neighbouring properties especially when many natural shelters are deciduous trees. This would have a
negative social impact as would branches that over grew into the neighbouring property as well. An
environmental implication of using natural shelter is that it provides a habitat for pests which may attack the
crop.
Connective / linking words &
phrases
(which accomplish the
explanation and/or analysis)