Marong map unit Qbc

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

Map Unit:	Quaternary basalt, moderate slope	Map Unit Symbol:	Qbc
		% of Study Area:	0.3

Land-form diagram for Marong map unit Qbc

General Description:
The soils on the basalt cone are shallow and stony. The profile on the moderate slope is similar to that on the crest. It is gradational with silty clay loam topsoils and red light clay subsoils. Depth is variable and scoria fragments are abundant throughout. Because this unit represents only a very small area in the Rural City, a detailed site description was not completed.

Site characteristics:

Parent material age:	Quaternary	Depth seasonal watertable:	> 10 m
Lithology:	Basalt	Potential recharge to groundwater:	Very high
Landform Pattern:	Lava plain	Flooding risk:	Nil
Element:	Slope/cone	Drainage:	Rapidly drained
Slope common:	20%	Depth to hardrock:	0.3 m
Slope range:	15-25%
Rock outcrop:	20 - 50%

Major vegetation: Cleared

Present land use: Grazing

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

Soil profile characteristics:

Permeability (measured - average, range):
Permeability (estimated):	Very rapid
Available water capacity:	50 mm H₂O
Linear shrinkage (B horizon):	N.A.

Soil profile description:

A	0-18 cm	Dark reddish brown (2.5YR3/4) silty day loam, weak structure, common scoria fragments, pH 6.5. Clear transition to
B	18-30 cm	Reddish brown (2.5YR4/6) light clay, weak structure, abundant scoria fragments, pH 7.0
C	30+ cm	Rock

Soil classification:

Factual Key (Northcote):	Gn 3.12
Australian Soil Classification:	Haplic, Mellic, Red, Kandosol; shallow, medium, silty, gravelly
Unified Soil Group:	GC

Interpretation of soil analyses*

Horizon	pH	Gravel %	E.C. (salts)	Nutrient Status	P	K	Al	Organic Matter	Dispersibility
A	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.
B	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.	N.A.

N.A.: Not Available * See Appendix 4 for analytical results

Land capability assessment

Land Use	Class	Major limiting feature(s)/ landuse
Agriculture (CTS values)	C₃T₄S₅	Very shallow depth to hardrock, low available water capacity, high gravel/stone/boulder content, very susceptible to sheet/rill erosion.
Effluent disposal (septic tanks)	5	Very shallow depth to hardrock, very rapid permeability – risk of polluting groundwater
Farm dams (earthen)	5	Very shallow depth to hardrock, very low suitability subsoil, very rapid permeability
Building foundations - slab	4	Moderate slope, high proportion of stones and boulders, shallow depth to hardrock
Building foundations - stumps/footings	4	High proportion of stones and boulders, shallow depth to hardrock
Secondary roads	4	Moderate slopes, high stone/boulder content, shallow depth to hardrock, highly dispersible subsoil
Urban residential	4	Secondary roads, building foundations
Rural residential	5	Farm dams, effluent disposal

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