NCEA Level 2 Agricultural and Horticultural Science (90452) 2006 — page 1 of 4
Assessment Schedule – 2006
Agricultural and Horticultural Science: Describe how techniques used to modify soil
water content optimise primary production (90452)
Evidence Statement
Q
Evidence
1 (a)
Soil factors include:
Stones indicate a light soil-type,
which, because of its high
porosity and rapid drainage
properties, means that water
received by natural or artificial
means is not retained by the soil.
This will result in reduced water
being available for plant
processes such as
photosynthesis.
(b)
(c)
Achievement
Climatic factors include:
Extended periods of bright
sunlight would indicate high
temperatures and high
evaporation at the soil surface
and high transpiration resulting
in a loss of soil water.
The shelter belt will reduce windspeed, thereby minimising the
evaporation of water from the
soil and the rate of water loss via
transpiration from the leaves.
CODE
2 (b)
Explains how TWO
factors cause
reduced soil water
content.
Plant factors include:
High leaf-area index means that
plant transpiration rates are very
high, resulting in high wateruptake and loss via the leaves,
thereby rapidly depleting soil
water-content.
CODE
2 (a)
Describes TWO
factors – soil, plant,
climatic – that
reduce soil water.
Judgement
Merit
Straw mulch helps retention of
soil-water and warmth, which is
essential for photosynthesis and
nutrient uptake at a time when
supply of water and nutrients is
vital for development of larger
fruit.
Mulching material also assists by
keeping fruit away from soil
contact, thereby reducing rotting
or marking of fruit, therefore
ensuring higher quality.
CODE
A
Describes the effect
of the shelter belt –
reduction of windspeed.
A
Describes the effect
of mulch on size or
quality of fruit – large
size or blemish-free.
A
M
Explains how
reduction in windspeed minimises
soil-water loss
occurring via
evaporation or
transpiration.
M
Explains how the
use of straw
mulching improves
the quality (size,
blemish-free) of the
strawberry crop.
M
Excellence
NCEA Level 2 Agricultural and Horticultural Science (90452) 2006 — page 2 of 4
Q
Evidence
3 (a)
An effective drainage system would
improve soil temperature, resulting in
increased plant process activity such
as respiration. The greater the
pasture production, the more feed is
available for milk production.
OR
An effective drainage system would
reduce the physical destruction of
pasture plants by treading and
burying (pugging), resulting in a
higher proportion of pasture being
available for cow consumption, and
therefore more nutrients for milk
production.
Achievement
CODE
3 (b)
Example:
Plastic land drainage piping is a
permanent and reliable sub-surface
drainage system consisting of
perforated piping laid 50 cm below
the soil surface. It is the best
technique, given the reliable rainfall
and clay soil-type – variables that
cannot be controlled and that will
continue to produce saturated soils.
Milk production depends on the high
nutrient intake by cows, which in turn
is dependent on high year-round
pasture growth.
Open ditches are of reduced benefit
on flat land if there is no natural
runoff and no subsurface drainage in
place. Pasture growth and milk
production will continue to suffer
from saturated soils. Excess energy
used by cows when moving through
sodden pastures means fewer
nutrients for milk production, and
there is the risk of stock losses from
animals falling into ditches and,
consequently, reduced milk
production.
Mole drainage is dependant on
moving excess water to a permanent
drainage system, and while clay
lends itself to moulding into artificial
tunnels, the high water content and
heavy foot traffic will lead to the
breakdown of mole tunnels. The
likelihood is that wet soils will persist,
and with them associated reduction
in pasture growth and milk
production.
CODE
Judgement
Merit
Describes the effect
of a drainage
system on pasture
(ie improvement or
maintenance).
Explains how a
drainage system
produces more
available feed, and
links this to
improved milk
production.
A
M
Excellence
Justifies by way of
comparison why
their selected
technique is better
than the
alternatives on
offer.
Critical thinking is
the driver of the
award of
Excellence. It is
possible for
Excellence to be
awarded if, when
justifying ANY
selected option,
the candidate
demonstrates
criticial thinking.
Critical thinking
involves
discrimination
when assessing,
interpreting and
judging
information. It
considers fact
rather than opinion,
bias, unstated
assumptions and
the like.
E
NCEA Level 2 Agricultural and Horticultural Science (90452) 2006 — page 3 of 4
Q
Evidence
4 (a)
The combination of sandy soil
and low rainfall produces soilmoisture stress about the time of
flowering. The early flowering
stage is vital because the
number of flowers produced
determines the number of seeds
that can be produced. The more
flowers produced and pollinated,
the higher the yield of seed.
CODE
4 (b)
Judgement
Merit
Achievement
Refers to how sandy
soil-type and low
rainfall reduce soil
water-content.
Explains the link
between available
water, number of
flowers and the yield
of seed.
A
M
Example:
Using the neutron probe is a
more accurate and less timeconsuming technique than the
alternatives. The resource states
that this is a farm of some size
(200ha) and with a range of
crops there will be competition
for the irrigation water resource.
It is therefore essential that the
farmer can plan in advance
which crops should be given
priority, when each should be
irrigated and how much water
should be applied.
Excellence
Justifies by way of
comparison why
their selected
technique is a better
method of water
scheduling than the
alternatives on offer.
Critical thinking is
the driver of the
award of Excellence.
It is possible for
Excellence to be
awarded if, when
justifying ANY
selected option, the
candidate
demonstrates criticial
thinking.
Critical thinking
involves
discrimination when
assessing,
interpreting and
judging information.
It considers fact
rather than opinion,
bias, unstated
assumptions and the
like.
Water budgeting lacks the
accuracy required because the
data necessary for calculations
relevant to a particular property
(eg evapotranspiration) is difficult
to ascertain and local newspaper
data may not apply. The method
requires daily calculation by the
producer, and this may not
always be possible.
Tensiometers require careful
installation and while the per-unit
cost is reasonable, the large
number required for this property
would be prohibitive.
Complicating their use would be
their exposure to cultivation and
irrigating equipment, all of which
have the potential to destroy the
tensiometers.
CODE
E
Judgement statement
Achievement
Achievement with Merit
Achievement with Excellence
3A
3M
1E+3M
NCEA Level 2 Agricultural and Horticultural Science (90452) 2006 — page 4 of 4