Marong map unit Qa3

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

Map Unit:	Quaternary alluvium, terrace (Bullock Creek)	Map Unit Symbol:	Qa3
		% of Study Area:	0.3

Land-form diagram for Marong map unit Qa3

General Description:
This narrow alluvial terrace extends along the length of Bullock Creek. The soils are young and consequently have not developed properties such as structure or mottles. The buried profile consists of four separate layers each representing different periods of deposition. A dark silty clay loam top soil has been deposited over a yellow brown fine sandy loam, a yellow orange clayey sand and a greyish brown fine sandy loam. The uses of this map unit are restricted because of its size and proximity to the creek.

Site characteristics:

Parent material age:	Quaternary	Depth seasonal watertable:	> 2 m
Lithology:	Alluvium	Potential recharge to groundwater:	Moderate
Landform Pattern:	Alluvial terrace	Flooding risk:	High
Element:	Flat	Drainage:	Well drained
Slope common;	0%	Depth to hardrock:	> 1.6 m
Slope range:	0-2%
Rock outcrop:	0%

Major vegetation: Red Gum, Grey Box, Blackwood, Onion Grass

Present land use: Recreation (major), grazing (minor)

Land degradation:	Water erosion		Wind erosion	Salting	Acidification
Land degradation:	Sheet/rill	Gully	Wind erosion	Salting	Acidification
Susceptibility	Low	Low	Low	Low	Low
Incidence	Low	Nil	Nil	Low	Nil

Soil profile characteristics:

Permeability (measured - average, range):	2503, 267-8573 mm/day
Permeability (estimated):	-
Available water capacity:	365 mm H₂0
Linear shrinkage (B horizon):	1.6 %

Soil profile description:

1A	0-7 cm	Brownish black (10YR3/1) silty clay loam, weak structure, subangular blocky peds 5-10 mm, smooth fabric, moderately firm consistence, high organic matter, pH 6.7. Clear transition to
2A	7-19 cm	Greyish yellow brown (10YR4/2) fine sandy loam, weak structure, angular blocky peds 2-5 mm, smooth fabric, moderately weak consistence, pH 6.7. Clear transition to
3A	19-68 cm	Dull yellow orange (10YR6/3) clayey sand, bleached (10YR8/3) when dry, apedal, sandy fabric, very weak consistence, pH 6.7. Clear transition to
4A	68-160+ cm	Greyish brown (7.5YR4/2) fine sandy loam, apedal, sandy fabric, very strong consistence, pH 6.7.

Soil classification:

Factual Key (Northcote):	Um/Uc
Australian Soil Classification:	Rudosol; very deep, thin, silty, non-gravelly
Unified Soil Group:	ML (68 - 160) cm

Interpretation of soil analyses*

Horizon	pH	Gravel %	E.C. (salts)	Nutrient Status	P	K	Al	Organic Matter	Dispersibility
1A	6.7	1.4	VL	M	D	S	S	H	L
2A	6.7	< 1	VL	L	D	S	S	L	L
3A	6.7	< 1	VL	VL	D	S	S	VL	L
4A	6.7	< 1	VL	L	D	S	S	VL	H

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)	C₃T₁S₄	Low permeability index
Effluent disposal (septic tanks)	5	High risk of flooding, very rapid permeability - risk of polluting groundwater and adjacent stream
Farm dams (earthen)	5	Very rapid permeability
Building foundations - slab	5	High risk of flooding
Building foundations - stumps/footings	5	High risk of flooding
Secondary roads	5	High risk of flooding
Urban residential	5	Secondary roads, building foundations
Rural residential	5	Farm dams, effluent disposal, secondary roads, building foundations

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