Information Sheet (catchment)
C9 - Soil Type Overview
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In the early days
of white settlement in the Sydney Basin, Port Jackson was chosen
as the anchorage because it provided a very suitable and safe harbour.
However the poor state of the soils in the vicinity caused problems.
Early settlers attempted agriculture on the Cumberland Plain but
the yellow and red podsols, which are highly acidic, contain low
phosphorus and are resistant to nitrogen fixation, proved difficult
to cultivate for crops introduced from England. These soils quickly
became less productive as they were depleted of nutrients so agriculture
spread to the Hawkesbury-Nepean River flats which proved far more
successful.
In the 1950’s
it was discovered that the fertility of the soil of the Cumberland
Plain could be improved by adding lime to increase the pH and adding
superphosphate to increase the phosphorus load of the soils. Market
gardens and dairying continued into the 1960s but today only 0.7%
of the catchment is classed as rural.
2.Map
Refer to Map 4 - Upper Parramatta River Catchment Soil Profile
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3. Description of Types
There are two major soil types present in the catchment.
These reflect the underlying geology.
- In the sub catchment of Darling Mills Creek the
soil is generally coarse to medium grained sands and sandy
loams. This tributary flows over Hawkesbury Sandstones which
are generally quartz rich, coarse grained sandstones. These
soils generally are of low-moderate fertility, less than
100 cms in depth and easily eroded in flood regimes.
- In the sub catchment of Toongabbie Creek the soils
are generally fine grained silts and clays. The major rock
type here is the Bringelly Shale from the Wianamatta Group.
These are composed of muds and silt with sparse sand. These
soils generally are of low to moderate fertility, less than
100 cms in depth and less easily eroded in flood regimes.
Along the river channels are much deeper fluvial soils,
(more than 250 cms) which are of moderate fertility. Many
disturbed soil terrains exist along the river channels and
across the flood plain
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Cracking clay soils at John Silverthorn Park
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4. Distribution
The predominant soil landscapes are Blacktown and Luddenham which
have been formed respectively by residual and erosional geomorphic
processes. These soil landscapes occur mainly within the Toongabbie
Creek sub-catchment.
The soil landscapes occurring in the Darling Mills
Creek sub-catchment include Hawkesbury, Gymea, Glenorie and Lucas
Heights. The following table lists the soil landscapes within
the catchment, their characteristics, depth, erosion hazard and
fertility based upon Chapman and Murphy (1989) and Bannerman and
Hazelton (1990).
5. Reasons
for Distribution
The distribution of soils in the catchment reflects the underlying
geology. The two geological types being the Wianamtta shales of
the Cumberland Plain to the south and west and the Hawkesbury Sandstone
of the Hornsby Plateau in the north east.
Fig C9.1 Soil Landscapes occurring in the Upper Parramatta River Catchment
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(Geomorphic Process)
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Soil Depth
(cms)
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Erosion hazard
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Fertility
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Concentrated Flows
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Non-concentrated Flows
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Birrong (fluvial)
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>250
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Low-moderate
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Low; topsoil moderate
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Blacktown (residual)
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<100
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Moderate-high
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Slight-moderate
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Low
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Glenorie (erosional)
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<100
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Moderate-very high
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High
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Low-moderate
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Hawkesbury (colluvial)
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<50
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Very high
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High-extreme
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Very low
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Luca heights (residual)
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50-150
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Moderate
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High
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Low
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Luddenham (erosional)
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<100
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Moderate – very high
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High-very high
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Low-moderate
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Picton (colluvial)
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50-200
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High
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High-very high
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Moderate-low
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South Creek (fluvial)
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Very deep
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Very high
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Extreme
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Low
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West Pennant Hills (colluvial)
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>200
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High – extreme
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Very high-extreme
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Moderate
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Disturbed terrain
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>100
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varies
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varies
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varies
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6. Other Resources and
Links
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Upper Parramatta River Catchment Trust www.uprct.nsw.gov.au
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Parramatta City Council www.parracity.nsw.gov.au
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Baulkham Hills Shire Council www.baulkhamhills.nsw.gov.au
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Holroyd City Council www.holroyd.nsw.gov.au
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Blacktown City Council www.blacktown.nsw.gov.au
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National Parks & Wildlife Service www.npws.nsw.gov.au
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Natural Resource Directory www.nrims.nsw.gov.au
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State Forest NSW www.forest.nsw.gov.au
·
Department of Land & Water Conservation www.dlwc.nsw.gov.au
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