Watchem Series

Soils included in this series have distinct texture contrasts between hard setting surface soil horizons and moderately to strongly pedal clayey subsoils. Sporadically bleached A2 ‘subsurface’ soil horizons are present. The uppermost subsoil layer, that is at least 15 cm thick, is mottled and dominantly red. The soil reaction trend is alkaline.

In the present survey, this series included two soil types and one phase.

Watchem Sandy Loam (WA sl)

Profile Morphology:

Surface Soil - A1 horizon

15-20 cm thick.
Greyish brown to reddish grey.
Sandy loam to loamy sand.

Surface Soil - A2 horizon

15 cm thick.
Brown to red, sporadically bleached.
Sandy loam to sandy clay loam.

Subsoil

Mottled red to red-brown (or yellowish red), with dark grey-brown, brown and/or yellow-brown. At depth, the main colours gradually become yellower and/or paler.
Medium to heavy clay.

Soil Inclusions:

Trace to slight amounts of soft and/or hard CaCO3 usually occur at about 40 cm.

Analytical data for selected depths down the profile:

Depth	pH	Total Soluble Salts	Sodium Chloride	Moisture Retention @ 15-Bar	Moisture Retention @ 1/3-Bar
.	.	%	%	%	%
A	8.2	0.017	*	3.8	7.9
B	8.8	0.046	*	27.5	48.9
C	9.4	0.073	0.001	24.4	45.3

* Sodium chloride contents were not measured and are expected to be very low (based on TSS < 0.05%).

Occurrence:

Watchem Sandy Loam usually occurs on the crests and upper slopes in the undulating plains.

Watchem Sandy Clay Loam (WA scl)

Profile Morphology:

Surface Soil - A1 horizon

About 7 cm thick (range 5-12 cm).
Brown to dark reddish brown.
Sandy clay loam.

Surface Soil - A2 horizon

5-10 cm thick.
Dark reddish brown to yellowish red, sporadically bleached.
Sandy clay loam (occasional sandy loam).
This horizon may occur only as nests of sporadic bleaching at the interface between the A and B horizons.

Subsoil

Mottled red-brown to yellowish red, with dark grey, dark reddish brown and/or yellowish colours. At depth, soil colours gradually become yellower and often less prominently mottled.
Medium to heavy clay.

Soil Inclusions:

Slight amounts of soft and/or hard CaCO3 usually occur at about 50 cm, increasing to light or moderate amounts with depth.

Analytical data for selected depths down the profile:

Depth	pH	Total Soluble Salts	Sodium Chloride	Moisture Retention @ 15-Bar	Moisture Retention @ 1/3-Bar
.	.	%	%	%	%
A	7.5	0.039	0.016	6.3	16.9
B	8.2	0.078	0.050	18.9	36.8
C	9.1	0.177	0.083	20.2	38.1

Occurrence:

Watchem Sandy Clay Loam usually occurs on the level areas in the gently undulating plains.

Phases:

Deep surface:

The overall depth to the clayey subsoil is about 30 cm (range 16-40 cm).
A2 horizons comprise about 70-90% of the surface soils.
Occurs mainly in localised level areas of the gently undulating plains.

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