Soil/Landform Unit - Kalkee plains

Looking south-west towards Katyil across the Kalkee plains

Area: 86 383 ha

3.69% of CMA region

North of the Wimmera River as it emerges from the Dissected Western Uplands are the clay plains for which the Wimmera region is renowned. The Kalkee plains are synonymous with the

self-mulching

grey clays that have supported cereal cropping for much of the last century. These clay plains (Kalkee plains) have been divided into two units with this unit comprising a significant proportion of the traditional Kalkee clay located north of Horsham. These clay soils are found mainly in a significant band running east-west north of Horsham before

calcareous

equivalents dominate further north. Landform components include very gentle rises and plains with drainage across these plains very subtle and often poorly defined. The self-mulching

Vertosols

have high clay contents that can be variable due to micro relief and presence of

gilgai

. Today these gilgai are very inconspicuous owing to continued cropping of these soils and levelling of many paddocks. Soils may also be susceptible to inundation and periodic waterlogging during significant rainfall events due to high clay contents when already saturated. The dominant remnant vegetation community is Plains Savannah. Other vegetation communities present include Low Rises Woodland, Ridged Plains Mallee, Plains Grassland and Plains Woodland.

Self-mulching soils within prior stream floodplains
	Kalkee plains near Kewell

Component	1	2	3	4
Proportion of soil-landform unit	15%	25%	55%	5%
CLIMATE Rainfall (mm)	Annual: 425
CLIMATE Rainfall (mm)	Annual: 425
Temperature (^oC)	Minimum 8, Maximum 21
Precipitation less than potential evapotranspiration	September–April
GEOLOGY Age and lithology	Quaternary paludal silt and clay; Neogene marine sand and silt (Parilla Sand)
GEOLOGY Age and lithology
Geomorphology	5.4 Clay plains with subdued ridges of the North West Dunefields and Plains
LANDUSE	Uncleared areas: nature conservation Cleared areas: dryland cropping; sheep grazing
LANDUSE
TOPOGRAPHY Landscape	Gently undulating plains (Kalkee plains)
TOPOGRAPHY Landscape	Gently undulating plains (Kalkee plains)
Elevation range (m)	100–150
Local relief (m)	2
Drainage pattern	Dendritic
Drainage density (km/km²)	0.4
Landform	Very gentle rises		Plains
Landform element	Broad rise crest	Rise slope (low)	Plain	Swamp
Slope and range (%)	2 (1-7)	4 (3-10)	2 (1-8)	0 (0-1)
Slope shape	Convex	Convex	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Savannah (38.5%), Plains Grassland (17.6%), Plains Woodland (13.3%), Other (6.3%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	Aeolian sand and silt	Marine sand and silt	Marine sand and silt, and paludal silt and clay	Marine sand and silt, and paludal silt and clay
SOIL Parent material	Aeolian sand and silt	Marine sand and silt	Marine sand and silt, and paludal silt and clay	Marine sand and silt, and paludal silt and clay
Description (Corangamite Soil Group)	Cracking clay soils (34) and sodic red texture contrast soils (39)	Cracking clay soils (34)	Cracking clay soils (34)	Seasonally wet soils: sodic yellow and grey texture contrast soils (33) and cracking clay soils (34)
Soil type sites	WIA6, WIA9, NA174	WIA6, WIA9, WIA5	WIA6, WIA9, WIA5	NA171, NA141, WIA6
Surface texture	Sandy loam - medium clay	Medium clay	Medium clay	Light clay
Permeability	Moderate	Moderate	Moderate	Slow
Depth (m)	1.5	> 3	> 3	> 3
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Hardsetting upper soil susceptible to sheet and rill erosion along with wind erosion when exposed. High clay surfaces result in restricted soil drainage, but can be variable due to micro relief (gilgai).Dispersive and deep subsoils susceptible to gully erosion on steeper slopes. Compaction of upper soil variable depending on soil depth and moisture content. Upper soil is susceptible to acidification.	High clay content results in restricted soil drainage, but can be variable due to micro relief (gilgai). Soils may be susceptible to inundation and waterlogging. Surface soils are friable and only slightly susceptible to wind erosion due to self-mulching and massive nature. Soils may be susceptible at critical moisture contents and have variable resilience to compaction.	High clay content results in restricted soil drainage, but can be variable due to micro relief (gilgai). Soils may be susceptible to inundation and waterlogging. Surface soils are friable and only slightly susceptible to wind erosion due to self-mulching and massive nature. Soils may be susceptible at critical moisture contents and have variable resilience to compaction.	Susceptible to seasonal inundation, waterlogging and ultimately soil salinity. Upper soils susceptible to sheet erosion and wind erosion when exposed.

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