Bloomfield (Symbol: Bf)

Profile No. 45 (Aldrick et al, 1992)

Geology
Palaeozoic granites, granodiorites, gneissic metamorphics and related coarse crystalline plutonic rocks.

Landform
In the context of this report, the Bloomfield map unit encompasses rolling to steep hills with an elevation range of about 350 to 1100 m and an elevation range of 90 to 300 m. The slope gradients exceed 15% but are generally much steeper, commonly 30 – 50%.

Bloomfield map unit: steep hills in the background; Dargo map unit: rolling low hills in the foreground.

Vegetation
Grassy dry forest with montane grassy woodland at higher altitudes.

Soils
The underlying rocks of this map unit weather relatively slowly and have high natural erosion rates due to the incomplete vegetation cover and steep slopes. This has resulted in shallow sandy soils that are weakly aggregated or apedal and exposed rock is common and may exceed 50% of the area. Soil may be up to
1.2 m depth in rock-free areas. The soils are generally brown sandy loams overlying reddish brown sandy clays to clayey sands. No separate components are described in this report and no soil pits were examined.

Profile No 45 (Aldrick et al, 1992)

Location: Ensay	Geo. Ref. 0577800E 5862200N
Australian soil classification: Melanic Eutrophic, Red CHROMOSOL	Brown texture contrast soil
General landscape description: Steep low hills
Geology: Palaeozoic granite
Site Description: Lower east facing slope (37% slope)
Land use: Grazing on annual pasture
Original vegetation: Open forest
Mapping unit: Bloomfield (previously mapped as Dargo, Component 1, but too steep for new unit definition)

Surface soil
A11	0-27 cm	Dark brown (7.5YR3/2); sandy loam; apedal; hard consistence dry; 5% granite fragments up to 8 mm; clear wavy change to:
A12	27-50 cm	Strong brown (7.5YR5/6); gritty sandy loam; apedal; hard consistence when dry; 15% granite fragments up to 8 mm; clear wavy change to:
Subsoil
B2	50 -80 cm	Yellowish red (5YR5/6); sandy clay; moderate coarse (25 mm) angular blocky structure; firm consistence moist; 25% quartz and weathering feldspar crystals up to 3 mm and dark mica grains;
C	80 – 90 cm+	Strong brown (7.5YR5/6); sandy clay loam; moderate medium (20 mm) angular blocky structure; weathering granite; friable consistence, moist.

• Bordering on a gradational soil but the slight texture contrast between the surface (A) horizons and the subsoil (B) horizons makes this a borderline texture contrast soil.

Horizon	Depth cm	Field texture	pH water	EC dS/m	Gravel %	Coarse sand %	Fine sand %	Silt %	Clay %	Field cap. % w/w	Wilt. point % w/w	PAW* water % w/w
A11	0-10	SL	5.9	<0.05	6	31	43	10	13
A11	10-20	SL		<0.05	12
A12	30-50	SL	6.7	<0.05	22	37	42	11	11
B2	60-80	SC	7.0	<0.05	18	30	25	15	31
C	80-90	SCL	7.1	<0.05	5	29	27	14	28

Depth	OrgC#	Total N	Exch. Al	Exchangeable cations meq/100 g							Ca:Mg	Na %
cm	%	%	ppm	Ca	Mg	K	Na	Total	H	CEC
0-10	2.2	0.16		4.0	1.0	0.5	0.05	5.6	8.2	13.7	4
10-20
30-50				4.4	0.8	0.3	0.08	5.6	2.2	7.8	5.5
60-80				10.6	2.5	0.5	0.3	13.9	4.3	18.2	4.2	2
80-90				11.3	2.9	0.5	0.4	15.1	4.8	19.9	3.9	3

• As the soils are sandy, the plant available water would be very low. However plants would be able to utilize light rain after the soils are dry.
• Sheet and rill erosion would be high and common where the topsoil is exposed.
• Soil depth in the steep cleared drainage lines is likely to be very shallow with considerable exposed rock.