Land Capability Assessment for Agricultural Land Use

This is an essential component on what your land can achieve as is and forms the bases of the use along with the soil testing.

Agricultural land in Victoria is classed to five (5) levels with land Class 1 and 2 being highly productive agricultural classes; although land class 3 with certain components can also be highly productive.

Soil and land are limited resources. They support a range of economic activities under different land uses. Appropriate land use and good management are essential to ensure that these resources are available for future generations. The variable qualities of soil (such as depth, texture, acidity, stoniness) and land (slope, aspect, geology) affect their capability to support different land uses without degradation of the soil resource. Land capability assessment is the term used describe various approaches that have been used since the 1960s (Klingebeil and Montgomery, 1961) to classify soil and land attributes according to the constraints or opportunities for particular land uses. In Victoria the Soil Conservation Authority (SCA) and successive government departments have applied systems of land capability classification for a number of land uses, based on the SCA publication of Rowe et al (1981). NRLinks has used Rowe et al for many years however other states in Australia have incorporate many other items into its assessment. QLD has amended to be more concise into 4 levels. Western Australia has a similar structure to Victoria with 5 classes.

 

The Agricultural land classes are:

• A – Crop Land: Land that is suitable for a wide range of current and potential crops with nil to moderate limitations to production.
  • A1: Suitable for a wide range of current and potential broadacre and horticultural crops
  • A2: Suitable for a wide range of current and potential horticultural crops only.
• B – Limited crop land: Land that is suitable for a narrow range of crops. The land is suitable for sown pastures and may be suitable for a wider range of crops with changes to knowledge, economics or technology.
• C – Pasture Land: Land that is suitable only for improved or native pastures due to limitations that preclude continuous cultivation for crop production. Some areas may tolerate a short period of ground disturbance for pasture establishment.
  • C1: Suitable for grazing sown pastures requiring ground disturbance for establishment; or native pastures on higher fertility soils.
  • C2: Suitable for grazing native pastures, with or without the introduction of pasture, and with lower fertility soils than C1.
  • C3: Suitable for light grazing of native pastures in accessible areas, and includes steep land more suited to forestry or catchment protection.
• D – Non-agricultural land: Land not suitable for agricultural use, including land alienated from agricultural use.

 

Capability Ratings

Five land capability classes are commonly used in Western Australia. Most properties consist of land with a range of capability classes. These classes are specific to the land use being considered. This means that the same area could be classed as capability class 1 for one use, and class 5 for another use.

• Class 1: Very few physical limitations present and easily overcome; risk of land degradation is negligible
• Class 2: Minor physical limitations affecting either productive land use or risk of degradation; limitations can be overcome by careful planning.
• Class 3: Moderate physical limitations significantly affecting productive land use of risk of degradation; careful planning and conservation measures are required.
• Class 4: High degree of physical limitation not easily overcome by standard development techniques or resulting in high risk of degradations; extensive conservation measures and careful ongoing management are required.
• Class 5: Severe limitations; use is usually prohibitive in terms of development costs or the associated risk of degradation.

 

• Class 1: Land that is inherently capable for intensive soil-based agriculture, particularly horticulture. This class includes landscapes with Ferrosols on more gentle slopes and some alluvial areas. The access to a constant water supply will generally improve the capability of the land. Some land is included in this category due to improved land management (e.g., drainage, water access). Land management limitations are nil to slight. Class 1 land covers around 3% of the total land area in the study area.
• Class 2: Land that is inherently capable for soil-based agriculture, including intensive horticulture and dairying. This class includes Ferrosols on steeper terrain (i.e., slopes >10%) and former swap landscapes that have been extensively drained and have organic rich soils that also require adequate site drainage. Land management limitations are slight. Class 2 land covers around 2% of the total land area in the study area.
• Class 3: Land that is inherently capable for soil-based agriculture at moderate to high intensity. The potential/capability may vary (e.g. according to slope, inherent fertility and drainage) but is often realised with access to a constant water supply. Many landscapes with deeper sandy soils are represented here- which are highly suited to horticulture once land-forming, drainage, fertilisers and irrigation is provided. Suitable landscapes with more favourable texture-contract soils (e.g., Deeper surface horizons, relatively friable and stable upper subsoils) are also included. Land management limitations are slight to moderate for intensive use. Class 3 land covers around 9% of the total land area in the study area.
• Class 4: Land that is not as inherently capable for intensive soil-based agriculture. Extensive agriculture (including broadacre cropping with suitable land management practices) and non-soil utilisation activities are often most appropriate, and more intensive grazing is possible in some higher rainfall areas or where consistent water supplies are available. Due to mapping resolution, some minor exclusion areas (i.e., Class 5) can be present where land attributes (e.g., slope) vary locally. Land management limitations are high to very high for intensive use. There are also likely to be some areas of land within this Class that may have higher capability (e.g., suitable terrain with soils that have deep sandy surface horizons) but that are not able to be identified at this stage due to the broad scale of soil/landscape mapping available across much of the study area.
• Class 5: Land that is excluded from this study. This includes Public Land, areas within the Urban Growth boundary (UGB), steep terrain, (i.e., slopes >20% in landscapes with Ferrosols and slopes >10% elsewhere) and areas with potential Coastal Acid Sulfate Soils (CASS). Class 5 land covers almost 50% of the total land area in the study area.

Technical Report- Assessment of Agricultural Land Capability in Melbourne’s Green Wedge and Peri-urban Areas – October 2018.

Land capability is the ability of land to support a given land use without causing damage. Assessment of land capability considers the specific requirements of the land use (e.g., rooting depth of soil water availability) and the risks of degradation associated with the land use (e.g., phosphorus export hazard or wind eroision).

Land capability assessments are a first step in assessing land suitability for a given use. ‘Suitability’ considers other factors such as economics, infrastructure requirements, labour access, water and energy access, conflicting and complementary land uses, and the policy framework.