NCEA Level 2 Agricultural and Horticultural Science (90451) 2010 — page 1 of 6
Assessment Schedule – 2010
Agricultural and Horticultural Science: Describe physical factors of the environment and techniques used
to modify them for plant production (90451)
Evidence Statement
Question
ONE
(a)
(i)
Achievement
with Merit
Achievement
Wind and Shelter
Describes how ONE physical
factor is affected by shelter.
Example:
 Sunlight is reduced by trees
in the area of land adjacent to
the shelter.
 Humidity is increased on the
inside of the shelter belt.
 Temperature is increased on
the inside of the shelter belt.
 The frequency of frost is
increased on the inside of the
shelter belt.
A1
(ii)
Explains how strong winds can
reduce fruit crop quality.
Example:
Strong winds result in fruit such
as apples “banging” each other,
resulting in bruising and
therefore a lowering of quality.
Strong winds may cause fruit
such as kiwifruit, that are grown
on a support system, to come in
contact with wires or wood,
causing marking and bruising,
thereby reducing crop quality.
M1
(b)
Describes a design feature of
effective natural shelter.
Example:
Explains how shelter improves
the yield of insect-pollinated
fruit crops.
Natural = plants.
Example:
Porosity of shelter should be
about 50%.
Shelter should be a continuous
length, with no gaps.
Insects such as bees require
calm conditions for flight
between hives and target fruit
crops. Shelter maintains these
conditions, allowing bees to
move from flower to flower, and
in doing so, pollinate crops,
resulting in optimum fruit set
and the potential for high yield.
A2
M2
Achievement
with Excellence
NCEA Level 2 Agricultural and Horticultural Science (90451) 2010 — page 2 of 6
Question
(c)
Achievement
with Merit
Achievement
Achievement
with Excellence
Describes the construction of
an artificial shelter.
Explains the effects of artificial
shelter on crop production.
Example:
Example:
Artificial shelter involves the
suspension between long
wooden poles of wind-cloth
netting of a desired porosity.
There are no roots associated
with artificial shelter, so vines
close to the shelter have no
competition for nutrients, water
and some light. Therefore there
is minimal drop-off in yields
from these rows, unlike the drop
in yields associated with natural
shelter. The incidence of bird
damage is reduced, due to
there being no nesting or
resting sites for birds.
Example:
M2
Because there are no roots
associated with artificial shelter,
vines close to the shelter have
ready access to nutrients and
water. Therefore there is
minimal drop-off in yields from
these rows, unlike the drop in
yields associated with natural
shelter. The incidence of bird
damage is reduced, due to
there being no nesting or
resting sites for birds.
A2
Compares the environmental
and economic impacts of
artificial and natural shelter.
Artificial shelter provides
“instant” protection from wind,
and the design of the cloth
allows for a desired porosity
factor. There is a cost
associated with the posts and in
the regular renewal of the windcloth netting, but this must be
counted against the $100 per
hour cost of trimming natural
shelter and the associated
clean-up.
Visually, artificial shelter
appears bland (some may say
unappealing), while green
foliage has a calming affect.
Need both techniques.
Need both environmental and
economic impacts.
E
NCEA Level 2 Agricultural and Horticultural Science (90451) 2010 — page 3 of 6
Question
TWO
(a)
Achievement
with Merit
Achievement
Achievement
with Excellence
Chill Requirements and Frost Prevention
Describes what a “chill
requirement” is.
Example:
A chill requirement is the
number of hours (eg 1,000 hrs)
below a specific temperature
(say, 7o C) required by a plant
to break dormancy.
A1
Explains the need for a chill
requirement when producing
crops such as grapes.
Example:
Chilling is needed to break
down chemicals that regulate
flower bud dormancy in
deciduous plants. If the chill
requirement is not met, the
plant will blossom poorly, and
over an extended time will have
an adverse effect on both yield
and quality.
M1
(b)
Describes how the technique is
used to prevent frosts.
Explains how technique
maximises fruit crop yields.
Example: Helicopter
Example: Helicopter
Movement of helicopters approx
20 m above the vines from
about 3am to 6am. This mixes
warm air above with cold air
below.
Using helicopters means that
the orchard temperature does
not fall below 0° C, (increasing
heat / preventing temperature
from dropping) thus preventing
a frost and therefore frost
damage to the buds and fruit,
thus maintaining the crop yield.
Example: Overhead sprinklers
Overhead sprinklers provide a
continual sprinkling of water,
which freezes on the trees.
A2
Example: Overhead sprinklers
Overhead sprinklers spraying
water on the developing buds
and flowers results in the water
freezing on them and in doing
so, provides latent heat
sufficient to stop freezing and
allowing further development
into mature fruit.
M2
(c)
Describes the action of wind
machines.
Explains how wind machines
are used in frost prevention.
Example:
Example:
Wind machines are basically a
large fan at the top of a 10 m
pole, which mixes warm air
from that height with the colder
air at ground level.
Fans mix hot air with cold air to
increase the overall
temperature throughout the
vineyard. They are turned on
when the air temperature drops
close to 1o C to avoid sub-zero
temperatures, which would
freeze and destroy buds that
would develop into fruit.
A2
M2
Compares the social and
economic impacts of using wind
machines and helicopters to
prevent frost.
Example:
Wind machines are expensive
and many are required per
vineyard to provide effective
protection. However, this must
be balanced against the $1,000
per hour rates for a large
helicopter; 25 hours will pay for
one wind machine, which
provides a permanent solution.
NCEA Level 2 Agricultural and Horticultural Science (90451) 2010 — page 4 of 6
Both techniques will provide a
similar result in terms of fruit
yields.
Socially, helicopters are
offensive, because of their
noise on calm nights, especially
in those grape-growing regions
close to cities / towns such as
Napier and Blenheim. There is
also a noise component with
wind machines, and their height
and number present a visual
hurdle, especially in winter
months.
Wind machines are permanent
fixtures under the direct control
of the grower. Once in place, a
turn of a switch begins their
operation, unlike helicopters
that have to be booked,
sometimes at short notice, and
with the prospect that one may
not be available.
Both techniques would be
equally effective given that their
mode of action (mixing hot air
with cold air) is the same, in
order that temperatures do not
drop below zero, and freeze
and destroy buds that would
develop into fruit. The presence
of wind machines provides
greater reliability, especially for
new growers who have yet to
establish their reputation with
helicopter operators. Large
established vineyards may be
able to justify owning a
helicopter.
Need both techniques.
Need both social and
economic impacts.
E
NCEA Level 2 Agricultural and Horticultural Science (90451) 2010 — page 5 of 6
Question
Achievement
with Merit
Achievement
THREE
Rainfall and Hail Protection
(a)
Describes the stages of crop
production when rainfall and
hail are undesirable.
Example:
When fruit crops are reaching
maturity and are about to be
picked.
A1
Achievement
with Excellence
Explains how rainfall or hail
reduces the quantity of highquality fruit available for export
markets.
Example:
Rainfall or wetting of the skin
surface results in contraction
and cracking (splitting) of fruit,
rendering it ineligible for export.
Hail at any time of the growth
cycle can decimate the crop by
physical damage to buds,
leaves and fruit leaving less
fruit, if any, to pick that have the
high quality required for export.
M1
(b)
Describes what a protective
cover looks like.
Example:
Protective covers are a
“marquee”-type structure
involving long poles and guy
ropes that suspend a nylon
mesh sheeting above the crop.
A2
Explains how the use of
protective cover maintains fruit
quality.
Example:
The force of hail stones is
absorbed by the mesh, and hail
is deflected to the side. This
prevents physical contact
between hail and fruit, and so
there is no physical damage
such as bruising or marking to
reduce fruit quality.
M2
(c)
Describes how hail cannons
operate.
Example:
Hail cannons are metal
structures mounted on a
concrete slab in the middle of
an orchard. They work by
igniting gas and firing sonic
booms into the air at the time of
a storm.
A2
Explains the effectiveness of
hail cannons in preventing hail
damage.
Compare the environmental
impacts of protective covers
and hail cannons.
Example:
Example:
Hail cannons are reputed to
provide protection by igniting
gas and firing sonic booms into
the air at short frequency as
storms approach. Any hail
stones in the impending storm
clouds are reduced to a slush
which, when it falls onto the
fruit, has minimal impact on the
outer surface.
Effective only in known hail belt
areas.
Protective covers are a
permanent installation and are
very visual – both the support
structures and the netting –
when fully rolled out. The use of
coloured netting material
reinforces the visual impact,
and it is the colour that many
people find offensive. In
comparison, one or two hail
cannons located in the centre of
an orchard are unobtrusive.
M2
There is concern that treated
poles used to support the
netting may leach chemical
preservatives such as arsenic
into the soil and contaminate
NCEA Level 2 Agricultural and Horticultural Science (90451) 2010 — page 6 of 6
both soil and water supplies.
Hail cannons produce a
deafening sonic boom that
impacts on people and
livestock, but they are usually
used for short periods of time
when hail is approaching, and
this is infrequent.
Need both techniques.
Need only environmental
impacts.
E
Judgement Statement
Achievement
Achievement with Merit
Achievement with Excellence
2 A1
2 M1
2 M1
2 A2
2 M2
2E