Marong map unit Qbf

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

Map Unit:	Quaternary basalt, very gentle slope	Map Unit Symbol:	Qbf
		% of Study Area:	3.2

Land-form diagram for marong map unit qbf

General Description:
The non rocky, very gentle slopes are a common component of the basalt plain. The dominant soils are duplex with dark reddish brown clay loam topsoils and red heavy clay subsoils which grade into bright brown, mottled heavy clays. Calcareous nodules occur at depth. Minor variations include a decrease in clay content in the subsoil so that profiles become gradational or uniform throughout. The minor drainage depressions are only slight and have similar soil types therefore they have not been delineated.

Site characteristics:

Parent material age:	Quaternary	Depth seasonal watertable:	> 2 m
Lithology:	basalt	Potential recharge to groundwater:	Moderate
Landform Pattern:	Lava plain	Flooding risk:	Nil
Element:	slope	Drainage:	Well drained
Slope common:	2%	Depth to hardrock:	> 1.5 m
Slope range:	0-3%
Rock outcrop:	0%

Major vegetation: Buloke, Yellow Box, Grey Box, Juncus spp., Capeweed, Onion grass, Wallaby Grass, Kangaroo Grass

Present land use: Grazing, cropping - broad acre

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

Soil profile characteristics:

Permeability (measured - average, range):	1370, 950 - 1680 mm/day
Permeability (estimated):
Available water capacity:	270 mm H₂O
Linear shrinkage (B horizon):	9.8%

Soil profile description:

A1	0 - 20 cm	Dark reddish brown (5YR3/3) clay loam, moderate structure, subangular blocky peds 5-10 mm, smooth fabric, moderately firm consistence, moderate organic matter, pH 5.4. Clear transition to
B21	20 - 38 cm	20-38 cm Reddish brown (2.5YR4/6) light medium clay, moderate structure, subangular blocky peds 10-20 mm, smooth fabric, moderately weak consistence, pH 6.5. Gradual transition to
B22	38 - 59 cm	Bright brown (7.5 YR5/6) heavy clay, many distinct red mottles, strong structure, subangular blocky peds 2-5 mm, smooth fabric, moderately weak consistence, pH 6.9. Gradual transition to
B23	59 - 90 cm	Bright brown (7.5YR5/6) heavy clay, a few distinct yellow mottles, weak structure, angular blocky peds 2-5 mm, smooth fabric, moderately firm consistence, less than 2% ironstone and basalt fragments, pH 8.0. Clear transition to
B3	90 - 150 + cm	Reddish brown (2.5YR4/6) heavy clay, many distinct yellow/orange mottles, strong structure, subangular blocky peds 2-5 mm, moderately strong consistence, many ferruginous and calcareous nodules, pH 9.3.

Soil classification:

Factual Key (Northcote):	Dr2.13 (major), Gn3.12/3, Uf6.31 (minor)
Australian Soil Classification:	Haplic, Eutrophic, Red, Chromosol; very deep, medium, clay 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	5.4**	3.9	VL	L	D	S	T	M	M
B21	6.5	1.9	VL	L	D	S	S	L	M
B22	6.9	<1	VL	M	D	S	S	L	M
B23	8.0	0.5	VL	M	D	S	S	L	H
B3	9.3	22.8	L	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)	C₃T₂S₃	Moderately susceptible to sheet/rill erosion, moderately dispersibile topsoil, moderate permeability index, climate
Effluent disposal (septic tanks)	2	Nil, however rapid permeability - risk of polluting groundwater
Farm dams (earthen)	5	Rapid permeability
Building foundations - slab	2	Nil
Building foundations - stumps/footings	2	Nil
Secondary roads	3	Universal Soil group
Urban residential	3	Secondary roads
Rural residential	5	Farm dams

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