Marong map unit Dgb

Back to: A Land Capability Study of the Rural City of Marong

Map Unit:	Devonian granodiorite, steep slope	Map Unit Symbol:	Dgb
		% of Study Area:	0.2

Land-form diagram for Marong map unit Dgb

General Description:
The steep slopes in the granodiorite are only a minor component of the Rural City. They are generally rocky and located adjacent to rocky crests on the rolling hills. The soils are very similar to those on the rocky crest; shallow, uniform coarse sands with dark brown sandy loam top soils. Pockets of deeper uniform sands and duplex soils can occur between outcropping tors.

Site characteristics:

Parent material age:	Devonian	Depth seasonal watertable:	>10 m
Lithology:	Granodiorite	Potential recharge to groundwater:	Very High
Landform Pattern:	Rolling low hills	Flooding risk:	Nil
Element:	Slope	Drainage:	Rapidly drained
Slope common:	33%	Depth to hardrock:	0.6 m
Slope range:	32 - 35%
Rock outcrop:	10 - 20%

Major vegetation: Long-leaf Box, Yellow Box, Grey Box, Blackwood, Buloke, Black Wattle, Wallaby Grass.

Present land use: Partially cleared, grazing

Land degradation:	Water erosion		Wind erosion	Salting	Acidification
Land degradation:	Sheet/rill	Gully	Wind erosion	Salting	Acidification
Susceptibility	High	Low	Moderate	Low	Low
Incidence	Moderate	Very low	Low	Low	Low

Soil profile characteristics:

Permeability (measured - average, range):	20080, 12923 - 29583 mm/day
Permeability (estimated):	-
Available water capacity:	96 mm H₂O
Linear shrinkage (B horizon):	Low (estimate)

Soil profile description:

A	0 - 20 cm	Dark red brown (5YR3/2) sandy loam, apedal, sandy fabric, loose consistence, high organic matter, pH 5.5. Clear transition to
C	20 - 60 cm	Dull red brown (5YR4/4) clayey sand, apedal, sandy fabric, loose consistence, many quartz fragments, pH 5.4. Gradual transition to
	60+ cm	Rock

Soil classification:

Factual Key (Northcote):	Uc 1.23 (major) Dy 3.11 (minor)
Australian Soil Classification:	Arenic, Rudosol; shallow, thin, loamy, non-gravelly
Unified Soil Group:	SM

Interpretation of soil analyses*

Horizon	pH	Gravel %	E.C. (salts)	Nutrient Status	P	K	Al	Organic Matter	Dispersibility
A	5.5**	21.2	VL	L	D	S	T	H	L
C	5.4**	29.0	VL	VL	D	S	T	L	L

VL : Very Low; L : Low; M : Moderate; H : High; VH : Very High; D : Deficient; S : Satisfactory; T : Toxic; **: Acid * See Appendix 4 for analytical results

Land capability assessment

Land Use	Class	Major limiting feature(s)/ landuse
Agriculture (CTS values)	C₃T₅S₄	Steep slope
Effluent disposal (septic tanks)	5	Steep slope, excessive permeability – risk of polluting groundwater
Farm dams (earthen)	5	Steep slope, shallow depth to hardrock, very low suitability of subsoil, excessive permeability.
Building foundations - slab	5	Steep slope
Building foundations - stumps/footings	4	Steep slope, high risk of slope failure
Secondary roads	5	Steep slope
Urban residential	5	Urban residential 5 Secondary roads, building foundations (slab)
Rural residential	5	Farm dams, effluent disposal, secondary roads, building foundations (slab)

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