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Land assessment and land capability maps
Thematic maps can be produced for a variety of purposes and varying scales, from a map of phosphorus export risk [213kb PDF] in the south west region to general maps showing areas of valuable horticultural land [350kb PDF] on the Swan Coastal Plain. Land resource maps have also been developed into various Agmaps CDs which incorporate map sheets and a large collection of technical notes relevant to agriculture and land resources.
Maps can also be purpose built. For example areas suitable for olive production in the Peel Region [2122kb PDF] were mapped in collaboration with Dr Stanley George Kailis, an honorary Research Fellow at the University of Western Australia. Another example is land management units for the Ellenbrook Catchment [1384kb PDF] mapped in collaboration with Martin Wells of Land Assessment P/L. Another example is a land capability assessment for grazing in the Shire of Murray [964kb PDF]
Because soil landscape maps have a high degree of variability, the maps are attributed proportionally using land units, which are areas with common landform and similar soils.
The basic methodology is as follows: The following 22 land quality ratings assigned to each land unit:
|
Description |
Acceptable codes (ratings) |
|
Ease of excavation |
H (high), M (moderate), L (low), VL (very low) |
|
Flood hazard |
N (nil), L (low), M (moderate), H (high) |
|
Land instability |
N (nil), VL (very low), L (low), M (moderate), H (high) |
|
Microbial purification |
VL (very low), L (low), M (moderate), H (high) |
|
pH at 0-10 and 50-80 cm depth |
Vsac (very strongly acid), Sac (strongly acid), Mac (moderately acid), Slac (slightly acid), N (neutral), Malk (moderately alkaline), Salk (strongly alkaline) |
|
Phosphorus export hazard |
L (low), M (moderate), H (high), VH (very high), E (Extreme) |
|
Rooting depth |
VS (<15), S (<30), MS (30-50), M (50-80), D (>80), VD (>150) cm |
|
Salinity hazard |
NR (no hazard), PR (partial or low hazard), MR (moderate hazard), HR (high hazard), PS (saline land) |
|
Salt spray exposure |
S (susceptible), N (not susceptible) |
|
Site drainage potential |
R (rapid), W (well), MW (moderately well), M (moderate), P (poor), VP (very poor) |
|
Soil absorption |
H (high), M (moderate), L (low), VL (very low) |
|
Soil water storage |
VL (<35), L (35-70), ML (70-100), M (100-140), H (>140 mm/m for 0-100 cm or the rooting depth) |
|
Soil workability |
G (good), F (fair), P (poor), VP (very poor) |
|
Subsurface acidification susceptibility |
L (low), M (moderate), H (high), P (presently acid) |
|
Subsurface compaction susceptibility |
L (low), M (moderate), H (high) |
|
Surface salinity |
N (nil), S, (slight), M (moderate), H (high), E (extreme) |
|
Surface soil structure decline susceptibility |
L (low), M (moderate), H (high) |
|
Trafficability |
G (good), F (fair), P (poor), VP (very poor) |
|
Water erosion hazard |
VL (Very low), L (low), M (moderate), H (high), VH (very high), E (extreme) |
|
Water repellence susceptibility |
N (Nil), L (low), M (moderate), H (high) |
|
Waterlogging/inundation risk |
N (nil), VL (very low), L (low), M (moderate), H (high), VH (very high) |
|
Wind erosion hazard |
L (low), M (moderate), H (high), VH (very high), E (extreme) |
These land qualities can be mapped individually (example), or combined to create land capability maps. Land capability maps are ranked for 1 to 5, where class 1 land has no limitations for the proposed land use and class 5 is severely limited. There are five standard land uses that have been applied to most surveys:
- grazing
- cropping - traditional and minimum tillage
- perennial horticulture and wine grapes
- annual horticulture
- septic tanks for rural residential developments
More land capability classifications can be added to suit specific projects or other land uses.
A report on land evaluation standards for land resource mapping is available.
Soil-landscape mapping data and derived products such as degradation hazards and land capability are available to view online at the NRM Info portal.
A major use for land capability and land degradation mapping includes land use planning. More information can be found at Agplan including further links to other state Government Planning agencies.
Contact Dennis Van Gool or Peter Tille
Page amended: November 2008