Marong map unit Dge

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

Map Unit:	Devonian granodiorite, gentle slope	Map Unit Symbol:	Dge
		% of Study Area:	4.6

Land-form diagram for Marong map unit Dge

General Description:

The gently undulating non-rocky slopes are a major component of the granodiorite land system. The soil types are similar to those found on gentle crests; yellow duplex with brown sandy loam top soils, hardsetting bleached A2 horizons and mottled heavy clay subsoils underlain by a siliceous hardpan. Some minor drainage lines have not been delineated as their soils are not significantly different, only wetter. Outcropping tors occur occasionally and are surrounded by uniform sands.

Site characteristics:

Parent material age:	Devonian	Depth seasonal watertable:	> 2 m
Lithology:	Granodiorite	Potential recharge to groundwater:	Low
Landform Pattern:	Undulating low hills	Flooding risk:	Nil
Element:	Slope	Drainage:	Well drained
Slope common:	6%	Depth to hardrock:	1.0 m (variable)
Slope range:	3 - 10%
Rock outcrop:	<2%

Major vegetation: Grey Box, Long-leaf Box, Yellow Box, Yellow Gum, Lightwood, Wallaby Grass, Rye Grass, Onion Grass

Present land use: Grazing - mainly sheep (major), residential (minor)

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

Soil profile characteristics:

Permeability (measured - average, range):	7, 3 - 12 mm/day
Permeability (estimated):
Available water capacity:	146 mm H₂O
Linear shrinkage (B horizon):	14.2 %

Soil profile description:

A1	0-9 cm	Greyish yellow brown (10YR4/2) sandy loam, weak structure, angular blocky peds 10-20 mm, rough fabric, very weak consistence, high organic matter, pH 5.0. Clear transition to
A21	9-23 cm	Dull yellow orange (10YR6/3) sandy loam, bleached (7.5YR8/4) when dry, weak structure, subangular blocky peds 10-20 mm, rough fabric, very weak consistence, pH 5.3. Clear transition to
A22	23-38 cm	Dull yellow orange (10YR7/3) sandy loam, bleached when dry, apedal, sandy fabric, loose consistence, granitic fragments are common, pH 5.7. Clear transition to
B2	38-76 cm	Greyish yellow brown (10YR6/2) heavy day, many distinct medium sized red mottles, weak structure, subangular blocky peds 20-50 mm, smooth fabric, very firm consistence, pH 5.6. Clear transition to
B3	76-100 cm	Greyish brown (7.5Y5/2) light clay, many faint red coarse mottles, moderate structure, angular blocky peds 10-20 mm, smooth fabric, moderately firm consistence, many coarse granitic fragments, pH 5.1
C	100 cm	Hardpan

Soil classification:

Factual Key (Northcote):	Dy 3.41 (major) Dy 2.41 (minor)
Australian Soil Classification:	Bleached-Sodic, Mesotrophic, Grey, Chromosol; moderate, thick, loamy, non-gravelly
Unified Soil Group:	CH

Interpretation of soil analyses*

Horizon	pH	Gravel %	E.C. (salts)	Nutrient Status	P	K	Al	Organic Matter	Dispersibility
A1	5.0**	3.1	VH	VL	D	S	H	L	L
A21	5.3	7.3	M	VL	D	D	L	L	L
A22	5.7	15.1	H	H	D	D	S	L	L
B2	5.6**	6.3	H	H	D	S	S	VL	H
B3	5.1	14.4	H	H	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)	C₃T₃S₄	Highly susceptible to wind and gully erosion, shallow depth to hardpan, high electrical conductivity in subsoil
Effluent disposal (septic tanks)	5	Very slow permeability
Farm dams (earthen)	4	Shallow depth to hardpan, low suitability of subsoil, highly dispersible subsoil
Building foundations - slabs	3	Gentle slope
Building foundations - stumps/footings	3	Moderate linear shrinkage
Secondary roads	4	Highly dispersible subsoil
Urban residential	4	Secondary roads
Rural residential	5	Effluent disposal

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