Level II Agricultural Business Operations
Horticulture
2
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1.
2.
3.
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Soil is made up of 3 main mineral
components
Sand
Silt
Clay
Proportion of each determines soil type
12 different soil types/textures
3
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Sand is gritty and breaks up if rolled
into a ball
Silt is smooth, silky or floury
Clay is sticky when wet, shiny when
smeared and holds shape
4
5
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Soil is a valuable source often overlooked.
Amount of nutrients depends on soil type,
rainfall, previous management and
previous crop
◦ GAP – Good Agricultural Practice
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How do you find out what’s in soil?
Soil sampling
Soil analysis
6
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Sample every 4-5 years for permanent crops
Vegetable crops every 2-3 years
Yearly in glasshouse
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Always sample a new or just rented field
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Ideally October – February
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◦ after previous crop has been harvested
◦ NOT following lime or fertiliser application
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Walk a “W” or “S”
pattern through
field
25 cores per
sample (avoiding
greenery)
Send to laboratory
for analysis
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Useful equipment
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Soil auger (can also use a spade)
Bucket
Sealable plastic bag
Permanent pen
Depth for collection depends on root zone
◦ Apples – 6” auger, collect under tree canopy
◦ Vegetables
 90cm (36”) from Jan – Spring for Soil Nutrient Supply
 60cm (24”) in autumn
 30cm (12”) for shallow rooted veg
Major nutrients in soil
 Nitrogen (N) – most
important for plant
growth
 Phosphorus (P)
 Potassium (K) – often
referred to as Potash
◦ Others important are
Sulphur (S), Magnesium
(Mg) and Calcium (Ca)
N
P
K
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Soil texture
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May affect
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◦ Soil structure
◦ Water availability and
retention
◦ Cultivation methods
◦ Nutrient retention
◦ Cropping potential
Organic Matter
Separate element to
soil test
◦ Must be requested
◦ Can affect how/what
nutrients are
availalbe
◦ Can affect plant
protection products
1.
pH
2.
Lime requirement
3.
Phosphorus index
4.
Potassium index
5.
Magnesium index
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A measure of soil acidity or alkalinity
pH scale from 0 – 14
 pH 7.0 is neutral
 Less than pH 7.0 is acidic
 Greater than pH 7.0 is alkaline
ACIDIC
0
1
2
3
NEUTRAL
4
5
6
7
ALKALINE
8
9
10 11 12 13 14
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Typical soil pH in Horticulture ranges from:
Acidic
5
6
Neutral
Alkaline
7
8
Apples
6.0-6.5
Strawberries
in soil
5.8
Most Vegetables
Most Cut Flowers
6.5
Brassica
Vegetables
7.5
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Soil pH
determines
nutrient
availability
for the
plant!
Soil Acidity
pH 5.0 (Very Strong
acidic)
pH 5.5 (Strongly
acidic)
pH 6.0 (medium
acidic)
N
P
K
53%
34%
52%
77%
48%
77%
89%
52%
100%
Liming increases the availability of soil nutrients.
Your fertiliser is more efficient if soil pH is at optimum level.
22
Conditions the soil
 Improves the availability of major
nutrients
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 Nitrogen, Phosphorus, Potassium, Sulphur,
Calcium & Magnesium
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Encourages micro-organisms in soil
 Break down organic matter releasing N
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Can help suppress some diseases
(Club root)
 Increases
earthworm activity
 Improves texture
 Improves
soil structure
Assume Field 9 is 3 acres (area).
How many tonnes/acre of lime is required in field 9?
Field area x lime requirement/acre
3 acres x 5.00 ton/acre =
Assume Field 9 is 3 acres.
How many tonnes/acre of lime is required in field 9?
Field area x lime requirement/acre
3 acres x 5.00 ton/acre = 15 ton/acre
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Granulated lime
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Pink lime
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Potassic lime
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Company specific products
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Index 0 – 5 or 6
◦ 0 – 2 = soil needs larger quantities of nutrient
◦ 3 = generally good index, though some nutrients
may be needed
◦ 4 and above = generally do not require additional
feeding
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Phosphate – form of phosphorus that is taken
up by the plant (P2O5)
Aids photosynthesis
Good for blooming and root growth
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Index 0 – 5 or 6
◦ 0 – 2 = soil needs larger quantities of nutrient
◦ 3 = generally good index, though some nutrients
may be needed
◦ 4 and above = little to no additional feeding
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Potash – form of potassium that is taken up
by the plant (K2O)
Aids photosynthesis
Improves fruit quality
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Valuable source of nutrients
Sample every 2-4 years
Use analysis to determine the amount
of nutrients in the soil
The higher the soil nutrient reserves
(Index), the lower the need for
additional nutrients
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The substance in which plants grow
 Soil
 Composts
 Soil-less or loam-less composts
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Consider container culture:
 Growing media must provide
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Physical characteristics
Balance between water and air
Biological factors
Chemical factors
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Stability
 Provide anchorage so that plant can root and be held
securely in the container
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Structure and texture
 Enough air spaces between particles so that water and
air can be held in the medium but also move through
medium.
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Water level for consistent growth
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Air filled porosity: the number and size of
pores (spaces) held between the particles of
growing media.
Air filled porosity controls
 Water drainage through the growing media
 Availability of water to the plant(s)
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Biological organisms (aka microbes) are
present in growing media – even sterilised
media
 Promote helpful microbes through feeding
 Deter harmful microbes by controlling moisture
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Chemical properties are the nutrients in
growing media
 Know the nutrients available
 Supplement with fertiliser if needed
 Fertiliser requirements will vary for plant type and growing
medium
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Organic growing media – derived from plants
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Peat
Wood-based
Coir (coconut fibre)
Green waste compost
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Inorganic growing media – derived from
minerals
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Perlite
Vermiculite
Sand
Grit
Rockwool
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Traditionally used as the main growing media
for container grown crops.
Excellent water holding capacity
pH
 Acidic
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Low nutrient value, so fertilisers are usually
added
Reduced use of peat will affect horticulture in
future
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http://www.bordnamonahorticulture.ie/profe
ssional/visit-bog
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Mainly used in a mixture with peat to reduce
the amount of peat
Composted bark, woodfibre, wood/paper
waste or sawdust
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Improves drainage
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Low pH
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Derived from the outer husk of coconuts
Used on its own in soft fruit production (in
bags or containers) and in propagation
Uniform particle size giving good waterholding capacity
Does not hold nutrients well – supplementary
liquid feeding required.
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Many local authorities and some private
companies produce green waste compost
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High (but variable) nutrient content
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High pH
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Usually mixed with other growing media or
used to add organic matter to soil
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Most often used as additives to other organic
growing media
Some can be used on their own in specific
cultural situations
 Hydroponics
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Perlite
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Alumino-silicate
Chemically inert
Light weight
Porous material
 Increase water uptake
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Vermiculite
◦ Derived from mica
◦ Can help balance
nutrients
◦ Very light weight
◦ Often used to cover
seeds in propagation
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Sand
◦ Use sharp sand
◦ Used to improve
drainage in other
media
 1:1 peat/sand mix –
seed germination
 3:1 peat/sand mix –
growing on
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Grit
◦ Crushed rock
◦ Larger particles than
sand
◦ Mostly used for
alpine plants in the
growing medium or
as top dressing
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Ideally, contact a reliable supplier
◦ Companies spend ££ to develop good mixes for
specific crops – take advantage!
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Standard mixes include
◦ Cuttings
◦ Germinating seedlings
◦ Potting
 Bedding
 Tree & Shrub
 Ericaceous (for acid loving plants)
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Lily compost
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Strawberry compost
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Ericaceous compost
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And more...
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What is it?
Rotating or changing the type of crop in one
field on a regular basis
Purpose is to
◦ Allow soil nutrients to replenish / avoid deficiency
◦ Avoid build up of disease in soil
◦ Avoid build up of pest population in soil
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What horticulture crops benefit from crop
rotation?
Any soil grown crop
◦ Vegetables
◦ Soft fruit (soil grown)
◦ Cut flowers (soil grown)
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Why not container grown?
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Orchards can be affected over the very long
term
Removing an old orchard
 Soil will benefit from green manure or grass ley
 One year
 Ploughed back in before replanting new orchard
 Puts organic matter back into soil
 Adds nutrients to soil
Year 1
Potato or
grass
Year 5
carrot or
parsnip
Year 4
Brassica
Home
field
Year 2
Leeks
Year 3
Legume
/ fertility
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Growing media
 Many options
 Crop dependant
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Crop rotation
 Most important to soil grown crops with annual
harvest
 Also beneficial in longer term / more permanent crops
 Prevents pest and disease build up
 Prevents extreme nutrient deficiency
Learning Outcome 7 – Describe the growth
stages of a crop group