Marong map unit Osc

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

Map Unit:	Ordovician sediments, moderate slope	Map Unit Symbol:	Osc
		% of Study Area:	0.8

Land-form diagram for Marong map unit Osc

General Description:
The sedimentary moderate slopes occur on hills of relatively high relief, including the metamorphic aureole. The soils are similar to those on gentler slopes; red duplex with fine sandy loam top soils, sporadically bleached A2 horizons and medium clay subsoils that occasionally contain mottles. Profiles tend to be shallower in comparison. Coarse fragments are common throughout the profile and on the soil surface. On the upper slopes of the metamorphic aureole, the soils become gradational with weakly structured reddish brown loam topsoils and greyish brown fine sandy clay loam subsoils. Coarse fragments are common. These soils are a transition between the red duplex and the shallow loams on the aureole crest.

Site characteristics:

Parent material age:	Ordovician	Depth seasonal watertable:	> 5 m
Lithology:	Sedimentary	Potential recharge to groundwater:	Moderate
Landform Pattern:	Rolling hills	Flooding risk:	Nil
Element:	Slope	Drainage:	Well drained
Slope common:	12%	Depth to hardrock:	0.7 m (variable)
Slope range:	10 - 32%
Rock outcrop:	2%

Major vegetation: Grey Box, Red Stringybark, Red Ironbark, Golden Wattle, Hedge Wattle, Wallaby Grass, Cat's Claw Grevillea.

Present land use: Native forest.

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

Soil profile characteristics:

Permeability (measured - average, range):	37, 15 - 90 mm/day
Permeability (estimated):	-
Available water capacity:	122 mm H₂O
Linear shrinkage (B horizon):	14.6%

Soil profile description:

A1	0-12 cm	Dull reddish brown (5YR4/3) fine sandy loam, weak structure, subangular blocky peds 20-50 mm, smooth fabric, moderately firm consistence, common subangular sedimentary and quartz gravel fragments, moderate organic matter,pH 6.5. Clear transition to
A2	12-30 cm	Hardsetting orange (5YR6/6) loam, sporadically bleached when dry, weak structure, subangular blocky peds 5-10 mm, smooth fabric, moderately firm consistence, a few organic segregations throughout, many angular coarse sedimentary fragments, pH 5. Clear transition to
B2	30-60 cm	Dull reddish brown(5YR4/4) medium clay, weak structure, subangular blocky peds 10-20 mm, smooth fabric, very firm consistence, pH 5.5. Gradual transition to
B3	60-70 cm	Dull reddish brown (5YR4/4) medium clay, moderate structure, subangular blocky peds 5-10 mm, smooth fabric, moderately firm consistence, many subangular sedimentary gravel, pH 10.

Soil classification:

Factual Key (Northcote):	Dr 2.33 (major), Gn 4.54 (minor)
Australian Soil Classification:	Subnatric, Red, Sodosol; moderate, medium, loamy, gravelly
Unified Soil Group:	CH

Interpretation of soil analyses*

Horizon	pH	Gravel %	E.C. (salts)	Nutrient Status	P	K	Al	Organic Matter	Dispersibility
A1	6.2	2.6	VL	M	D	S	S	H	L
A2	4.7**	3.1	VL	VL	D	D	T	H	H
B2	7.3	2.9	M	H	D	S	S	L	VH
B3	9.0	62.9	H	H	D	S	S	VL	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)	C₃T₄S₅	Very susceptible to sheet/rill erosion
Effluent disposal (septic tanks)	4	Shallow depth to hard rock, moderate slope, slow permeability
Farm dams (earthen)	5	Shallow depth to hard rock, very low suitability of subsoil, very dispersible subsoil
Building foundations -* slab	4	Moderate slope
Building foundations - stumps/footings	3	Moderate slope, moderate risk of slope failure, moderate linear shrinkage, shallow depth to hardrock
Secondary roads	5	Very dispersible subsoil
Urban residential	5	Secondary roads
Rural residential	5	Farm dams, secondary roads

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