EGC211

Location: Benambra (East of township)

Australian Soil Classification: Eutrophic, Subnatric, Black SODOSOL

Map Unit: Benambra (Component 1)
Previous Site Name: EG211

General Landscape Description: Almost level plain
Land Use: Lucerne
Native Vegetation: Montane grassland
Geology: Pleistocene to recent alluvial deposits



Photo taken from pit looking towards the north-east. The narrow present flood plain of
Morass Creek is in the middle ground

Surface soil
A1	0 – 25 cm	Very dark greyish brown (10YR3/2); clay loam; strong medium (10 -20 mm) granular structure; weak consistence dry; pH 5.0; abrupt change to:
Subsoil
B21	25 – 55 cm	Very dark greyish brown (10YR3/2); medium clay; coarse (20 – 50 mm) strong columnar structure; strong consistence dry; pH 6.5; diffuse change to:
B22	55 – 90 cm	Very dark greyish brown (10YR3/2) mottled with yellowish brown (10YR5/4); medium clay; coarse (20 – 50 mm) moderate prismatic structure; strong consistence dry; pH 7.8; diffuse change to:
B23	90 – 115 cm	Greyish brown (10YR5/2) and yellowish brown (10YR5/6) with distinct very dark greyish brown (10YR3/2) mottles; medium clay; moderate coarse (20 – 50 mm) prismatic structure; very firm consistence dry; pH 8.2.

• Texture contrast between the surface (A1) horizon and subsoil (B21) horizon

Horizon	Horizon Depth (cm)	pH (water)	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
A1	0-25	5.0	0.17	4.0	0.32	17	11.0	7.0	3.7	0.52	0.24	9	33	24	23	35.9	12.9
B21	25-55	6.5	0.06	1.1	0.08		7.4	6.0	6.9	0.2	1.3	11	29	19	36	30.9	15.9
B22	55-90	7.8	0.09	0.66				6.2	7.3	0.25	2.2	3	27	23	41	38.9	18.9
B23	90-115	8.2	0.16	0.39				6.1	6.4	0.16	3.3	12	36	17	34	33.4	16.2

• Plant available water is considered to be moderate, based on an effective rooting depth of 55 cm.

• The surface soil is strongly acid. However the level of exchangeable aluminium is low (17 mg/kg) and is unlikely to affect the growth of aluminium sensitive species, particularly as the soil becomes alkaline with depth. Lime can be used to increase soil pH but a pH/aluminium test is best performed by taking samples across the paddock and bulked together. The use of test strips to observe lime response could be used as an aid in evaluating its cost/benefit. At a pH of 5.0, a pH response would be expected.
• Potassium levels in the surface soil are moderate and plant responses to potassium fertiliser is unlikely.
• Salinity is not a problem in the surface soil.
• Deficiencies of molybdenum and phosphorus may occur in the strongly acid surface soils and increasing the pH by lime application should enable the phosphorus (from superphosphate) and molybdenum to become more available.
• The nutrient holding capacity of the surface (A1) horizon is moderate (based on the sum of the exchangeable calcium, magnesium, potassium and sodium cations).

• The pH increases with depth, thus allowing the successful growing of deep rooting aluminium sensitive species (e.g. lucerne).
• The coarse strong prismatic nature of the clay B horizon confines the roots to cracks and makes it difficult for the roots to fully exploit the soil. As the subsoil is sodic and the deep subsoil strongly sodic, root and downward water movement may be restricted.