SFS18

Location: Mt Gow

Australian Soil Classification: Calcic, Epipedal, Black VERTOSOL

General Landscape Description: Flat plain.
Site Description: Canola stubble in raised beds. Previously phalaris pasture was grown. Southern Farming Systems (SFS) trial site.
Geology: Weathering basaltic rock.

SFS18 Landscape

Soil Profile Morphology:

Surface Soil			SFS18 Profile
Ap	0-20 cm	Very dark greyish brown (10YR3/2); large cracks visible at surface; medium clay; strongly pedal, thin surface mulch of fine polyhedral peds or sometimes a thin weak crust fractured by cracks, underlain by coarse polyhedral and subangular blocky structure; very firm to strong consistence dry; pH 5.7; abrupt change to:
Subsoil
B21t	20-50 cm	Very dark grey (10YR3/1); heavy clay; coarse prismatic, parting to coarse polyhedral structure (main prismatic units clearly defined by deep cracking to 60+ cm depth); slickensides (>50 mm) begin at 45 cm depth; pH 7.0; gradual change to:
B22ss	50-70 cm	Very dark greyish brown (10YR3/2) with many dark yellowish brown (10YR4/4) mottles; heavy clay; prominent slickensides evident; pH 7.8; gradual change to:
C	70+ cm	Hard rounded weathering basaltic rock; pH 8.6.

Soil structure in raised bed.

Wide (>10mm) cracks in bed farrow, associated with subsoil structure.

Subsoil peds.

Key Profile Features:

Clay texture throughout soil profile.
Significant cracking when profile is dry.
Prominent slickensides in subsoil.

Soil Profile Characteristics:

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	Moderately Acid	Low-Medium	Non-Sodic	None¹
Subsoil (B21 horizon)	Neutral	Low-Medium	Sodic	Slight²
Deeper subsoil (at 50+ cm)	Strongly Alkaline	Low-Medium	Strongly Sodic	Moderate

¹ Slight dispersion after remoulding. ² Moderate dispersion after remoulding.
Image: SFS18 graphs

The pH in the surface is moderately acid. The pH in the upper subsoil is neutral becoming strongly alkaline with depth.

The salinity rating is low to medium throughout the whole profile.

The surface is non sodic. The upper subsoil is sodic becoming strongly sodic with depth.

The clay content is moderate throughout the profile.

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl₂)	EC dS/m	NaCl %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
Ap	0-20	5.7	5.2	0.46	0.03	7.9	7.9	2.4	0.8
B21 (i)	20-30	7.0	6.3	0.43	0.02	7.4	13	2.9	3.6
B21 (ii)	30-50	7.8	7.2	0.31	0.02	7.8	14	2.4	4.8
B22	50-70	8.6	7.8	0.47	0.03	8.1	18	1.9	6.6

Horizon	Horizon Depth (cm)	Oxidisable Organic Carbon %	Total Nitrogen %	Exchangeable Aluminium mg/kg	Exchangeable Acidity meq/100g	Field Capacity pF2.5	Wilting Point pF4.2	Coarse Sand (0.2-2.0 mm)	Fine Sand (0.02-0.2 mm)	Silt (0.002-0.02 mm)	Clay (<0.002 mm)


Ap	0-20	3.3	0.37	5	16	38	23	4	29	17	41
B21 (i)	20-30					44	27	2	26	14	51
B21 (ii)	30-50					47	31	2	26	15	51
B22	50-70					52	35	2	24	17	53

Note: Depths for chemistry and morphology do not match, as soil samples were not collected within the same depths that the morphology was described.

Management Considerations:

Whole Profile

Plant available water capacity (PAWC) is considered to be low/medium (estimated at 100 mm) in the upper 70 cm of this soil profile. Effective rooting depth (ERD) is restricted to 70 cm due to the basalt below this depth.

Profile Described By: Richard MacEwan (December 1999).

Page top