GL162

Australian Soil Classification: Melanic, Mottled-Subnatric, Brown SODOSOL (confidence level 1)

General Landscape Description: Undulating rises
Site Description: Upper slope (8%)
Land Unit: Dundas Trachyte
Geology: Jurassic tracyte
General Land Unit Description: There are a few isolated outcrops of Jurassic trachyte in the north-western portion of the study area, with the largest outcrop being north east of Coleraine. There are also some colluvial slopes on the edge of trachyte outcrops around the Dundas and Merino Tablelands.

The trachyte hills often have rock outcrop and reasonably shallow soils on the crests and upper slopes. The main soil type on the upper slopes is a Brown Sodosol although Chromosol also occur and they are commonly sodic at depth. The soils on the colluvial slopes tend to be black cracking clays (Vertosols) or Black Vertic Sodosols. These soils are similar to the black soils of the dissected Merino Tablelands land unit. The soils on these slopes are a complex mix of different soil forming processes.

This site is located on the edge of a small band of Trachyte, below granite (GL161). Rock outcrop is evident. A Trachyte hill is opposite this site. This site is an example of the common soil type that occurs to the north of the study area. The soils on the low hills and rises that have outcropping bedrock tend to be similar to this soil type although they are often shallower.







Soil Profile Morphology:

Horizon	Depth (cm)
A11	0–10	Very dark grey (10YR3/2); clay loam; weak to moderate fine to coarse subangular blocky structure;firm consistence, dry; very few small subangular to angular trachyte pebbles; pH 5.6; diffuse change to:
A12	10–40	Black (5YR2.5/1); clay loam; weak fine to medium subangular blocky structure; firm consistence, moist; very few small subangular to angular trachyte pebbles; pH 6.0; clear and wavy change to:
A13	40-65	Dark reddish brown (10YR3/2); light clay; weak coarse subangular blocky parting to strong very fine granular structure; weak consistence, wet; very plastic, wet; very few large subangular blocky trachyte pebbles; pH 6.3; clear and wavy change to:
B2	65-110	Olive brown (2.5Y4/4) , with many distinct medium yellowish brown (10YR5/6) mottles; heavy clay; moderate fine to medium polyhedral structure; very plastic, wet; contains very few large subangular blocky trachyte pebbles; pH 6.3; clear to abrupt and wavy change to:
C	110-150	Weathered Trachyte.

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC dS/m	Organic Carbon %	Total Nitrogen %	Exchangeable Aluminium ppm	Exchangeable Acididty meq/100g	Exchangeable Cations				Coarse Sand (0.2-2.0 mm) %	Fine Sand (0.02-0.2 mm) %	Silt (0.002-0.02 mm) %	Clay (<0.002 mm) %	Field Capacity % w/w	Wilting Point % w/w
									Ca	Mg	K	Na
									meq/100g
A11	0–10	5.6	4.8	0.07	4.7	0.34	11	13	3.8	3.7	0.18	0.43	25	20	15	34	29.2	16.2
A12	10–40	6.0	5.1	0.07			<10	12	4.3	4.7	0.17	0.58	20	20	12	41	27.8	16.6
A13	40-65	6.3	5.3	0.06			<10	9	2.9	4	0.16	0.5	34	14	9	39	22.9	15.1
B2	65-110	6.3	5.7	0.2			<10	9.3	3.4	14	0.19	1.8	3	3	4	90	54.9	32.7

• Deep organic topsoil
• Strong texture contrast between topsoil and subsoil
• Mottled subsoil
• Marginally sodic subsoil
• Deeper topsoil dispersive when worked when wet