22175 version 1
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Demonstrate knowledge of soil properties and their effect on plant
growth
Level
3
Credits
10
Purpose
People credited with this unit standard are able to: describe the formation of
soil; describe the soil water properties of soil; describe the chemical
properties of soil; describe the biological properties of soil; and describe how
modifying soil properties can influence plant growth.
Subfield
Horticulture
Domain
Production Horticulture
Status
Registered
Status date
25 July 2006
Date version published
25 July 2006
Planned review date
31 December 2011
Entry information
Open.
Replacement information
This unit standard and unit standard 22174 replaced unit
standard 14, unit standard 33, unit standard 34, and unit
standard 35.
Accreditation
Evaluation of documentation and visit by NZQA, industry
and teaching professional in the same field from another
provider.
Standard setting body (SSB)
Primary Industry Training Organisation
Accreditation and Moderation Action Plan (AMAP) reference
0032
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Special notes
The New Zealand Soil Classification is used in this unit standard as the basis for
describing soils in New Zealand. Information on the New Zealand Soil Classification is
available at http://soils.landcareresearch.co.nz.
 New Zealand Qualifications Authority 2016
22175 version 1
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Elements and performance criteria
Element 1
Describe the formation of soil.
Performance criteria
1.1
Soil formation is described in terms of major contributing factors and supported
by examples.
Range
1.2
Soil profile formation is described in terms of main horizons and supported by
examples.
Range
1.3
contributing factors may include but are not limited to – parent
material, climate, topography, organisms, time, aspect and
vegetation.
O, A, B, C horizons.
Formation of soil texture and structure is described in terms of the influence on
soil properties.
Range
properties – water and air movement, pore space, structural
stability, soil warming, nutrient retention and leaching, plant root
penetration, ease of cultivation.
Element 2
Describe the soil water properties of soil.
Performance criteria
2.1
Soil water is defined in terms of levels, movement, and retention characteristics
and factors.
2.2
Soil water is described in terms of saturation, field capacity, easily available
water, and permanent wilting point.
2.3
Excess and insufficient water effects are outlined in terms of soil properties and
plant growth.
Element 3
Describe the chemical properties of soils.
Performance criteria
3.1
Soil pH is outlined in terms of its range and effect on nutrient availability, soil
structure and organisms, and plant growth tolerances.
 New Zealand Qualifications Authority 2016
22175 version 1
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3.2
The description identifies factors that influence soil nutrient availability.
Range
3.3
Macronutrients and major trace elements are identified by name and chemical
symbols.
Range
3.4
pH, nitrogen and phosphate fixation, texture, soil organisms,
mycorrhizal association.
all macronutrients and trace elements significant to one type of
horticulture production.
Common nutrient deficiencies of New Zealand soils are described in terms of
their symptoms and effects on plant growth.
Range
five elements – phosphorus, potassium, sulphur, nitrogen,
magnesium; and
three micronutrients.
Element 4
Describe the biological properties of soil.
Performance criteria
4.1
Humus formation is described in terms of decomposition of organic matter by
soil organisms and favourable conditions.
4.2
The influences of organic matter on soil are defined in terms of physical and
chemical properties.
Range
4.3
The functions of soil organisms are outlined in terms of their effects on plant
growth.
Range
4.4
water and nutrient retention, soil structure, soil organisms, soil
texture, soil temperature carbon/nitrogen ratios.
bacteria, fungi, earthworms, soil pests and pathogens.
The functions of trichoderma and other beneficial micro organisms on soil
properties and plant growth is described.
 New Zealand Qualifications Authority 2016
22175 version 1
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Element 5
Describe how modifying soil properties can influence plant growth.
Performance criteria
5.1
Major factors are described in terms of their affect on soil suitability for plant
growth.
Range
5.2
nutrient retention and availability, water holding capacity, drainage,
organic matter, compaction.
Practices used by producers are outlined in terms of maintaining and improving
soil suitability for plant growth.
Range
select five from – conservation and/or minimum tillage,
conventional tillage, drainage, irrigation, green crops, crop
residues, liming, fertilising, crop rotations.
5.3
Management of the soil is described when physical, chemical and biological
properties are modified.
5.4
Practices used by producers for the maintenance of sustainable soil
management are described.
Range
fertiliser usage, erosion control, reducing nutrient leaching,
contouring, mulching, crop planting, inter planting, riparian
planting.
Please note
Providers must be accredited by the Qualifications Authority, or an inter-institutional body
with delegated authority for quality assurance, before they can report credits from
assessment against unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by the Qualifications Authority before
they can register credits from assessment against unit standards.
Accredited providers and Industry Training Organisations assessing against unit standards
must engage with the moderation system that applies to those standards.
Accreditation requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Primary Industry Training Organisation via their website
www.primaryito.ac.nz if you wish to suggest changes to the content of this unit standard.
 New Zealand Qualifications Authority 2016