Marong Map unit Osg

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

Map Unit:	Ordovician sediments, drainage depression	Map Unit Symbol:	Osg
		% of Study Area:	3.2

Land-form diagram for Marong map unit Osg

General Description:
Drainage lines are numerous throughout the sedimentary hills. Those that are mapped may be slightly exaggerated in width, while very small drainage lines have not been mapped. As with all drainage units, the soils are variable. The dominant soil type is yellow duplex with hardsetting dark brown loam top soils, bleached horizons and mottled, yellowish clay subsoils. Occasionally the texture difference throughout the profile is gradational. In minor drainage lines the clay subsoils can be slightly redder.

Site characteristics:

Parent material age:	Ordovician	Depth seasonal watertable:	2 - 5 m
Lithology:	Sediments	Potential recharge to groundwater:	Low
Landform Pattern:	Rolling hills - undulating low hills	Flooding risk:	High
Element:	Drainage depression	Drainage:	Poorly drained
Slope common:	2%	Depth to hardrock:	1.1 m
Slope range:	1 - 3%
Rock outcrop:	0%

Major vegetation: Grey Box, Red Ironbark, Yellow Box, Golden Wattle, Hedge Wattle, Black-anther Flax-lily, Wallaby Grass

Present land use: Native forest

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

Soil profile characteristics:

Permeability (measured - average, range):	66, 10 - 130 mm/day
Permeability (estimated):	-
Available water capacity:	164 mm H₂O
Linear shrinkage (B horizon):	8.3 %

Soil profile description:

A1	0-9 cm	Hardsetting dark brown (7.5YR3/4) fine sandy loam, weak structure, subangular blocky peds 5 -10 mm, rough fabric, very weak consistence, less than 2% angular medium sized sedimentary fragments, pH 5.0. Clear transition to
A2	9-32 cm	Dull yellowish brown (10YR5/3) fine sandy loam, bleached (10YR7/2) when dry, hardsetting, common faint medium sized yellow and orange mottles, weak structure, subangular blocky peds 10 -20 mm, smooth fabric, moderately weak consistence, less than 2% organic segregations, a few angular medium sized sedimentary fragments, pH 5.4. Clear transition to
B21	32-54 cm	Greyish yellow brown (10YR6/2) light clay, common medium sized distinct yellowish brown mottles, moderate structure, angular blocky peds 5 -10 mm, smooth fabric, moderately weak consistence, pH 6.1. Clear transition to
B22	54-80 cm	Greyish yellow brown (10YR5/2) light clay, many medium sized distinct bright yellowish brown mottles, moderate structure, angular blocky peds 5-10 mm, smooth fabric, very firm consistence, less than 2% angular medium sized sedimentary fragments, pH 6.2. Abrupt transition to
B23	80-111 cm	Bright brown (7.5YR5/6) light sandy clay loam, massive, earthy fabric, moderately firm consistence, many angular medium sized metamorphic gravel fragments, pH 6.8. Clear transition to
C	111 cm	Rock

Soil classification:

Factual Key (Northcote):	Dy3.42 (major) Dy3.43, Dr2.43, Gn3.92/3, Gn3.02/3 (minor)
Australian Soil Classification:	Bleached - Mottled, Magnesic, Grey, Chromosol; deep, thick, loamy, non-gravelly
Unified Soil Group:	CL

Interpretation of soil analyses*

Horizon	pH	Gravel %	E.C. (salts)	Nutrient Status	P	K	Al	Organic Matter	Dispersibility
A1	5.0**	3.0	VL	D	S	S	S	H	L
A2	5.4**	3.0	VL	D	S	S	S	M	L
B21	6.1	0.7	VL	D	S	S	S	L	H
B22	6.2	4.3	VL	D	S	S	S	VL	H
B23	6.8	21.9	VL	D	S	S	S	VL	M

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)	C₃T₂S₄	Highly susceptible to gully erosion
Effluent disposal (septic tanks)	5	Poorly drained, high risk of flooding
Farm dams (earthen)	4	Shallow depth to hardrock, low suitability of subsoil, high dispersible subsoil
Building foundations - slab	5	Poor drainage, high risk of flooding
Building foundations - stumps/footings	5	Poor drainage, high risk of flooding
Secondary roads	5	Poor drainage, high risk of flooding
Urban residential	5	Secondary roads, building foundations
Rural residential	5	Effluent disposal, secondary roads, building foundations

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