LS13a

Location: Netherby

Australian Soil Classification: Epicalcareous-Epihypersodic, Self-mulching, Grey VERTOSOL

Northcote Factual Key: Ug 5.2
Great Soil Group: grey clay

General Landscape Description: Low lying area of gently undulating plain.
Site Description: Undisturbed roadside reserve.
Native Vegetation: Black Box (Eucalyptus largiflorens) and Lignum Bush (Muehlenbeckia cunninghamii) is the natural vegetation.

LS13A Landscape

LS13A Landscape another perspective.

Soil Profile Morphology:

Surface Soil

A1	0-10 cm	Dark yellowish brown (10YR3/3); medium clay; self-mulching; strong fine blocky structure; strong consistence dry; pH 8.4; clear change to:	LS13A Profile
Subsoil
B21	10-30 cm	Dark yellowish brown (10YR4/2); heavy clay; weak coarse prismatic, parting to strong medium blocky structure; very strong consistence dry; contains a few (2-5%) soft carbonate segregations; pH 9.0; clear and wavy change to:
B22	30+ cm	Strong brown (7.5YR4/6); medium heavy clay; strong medium subangular blocky structure; strong consistence dry; contains a common (> 20%) amount of soft carbonate; pH 9.2.

Key Profile Features:

• Clay texture throughout profile.
• Self-mulching surface soil.
• Occurrence of significant cracking in the soil profile when dry. Cracking often appears at soil surface.

Soil Profile Characteristics:

-	pH	Salinity	Sodicity	Dispersion
Surface (A1 horizon)	Moderately Alkaline	Low	Non-Sodic	Slaking, No dispersion1
Subsoil (B21 horizon)	Strongly Alkaline	Low	Strongly Sodic	None2
Deeper Subsoil (at 50 cm)	Strongly Alkaline	High	Strongly Sodic	Strong

¹ Slight dispersion after remoulding. ² Strong dispersion after remoulding.

The surface soil is moderately alkaline. The subsoil is strongly alkaline throughout.

The salinity rating is low in the surface and upper subsoil becoming high with depth.

The surface is non-sodic. The subsoil is strongly sodic.

Chemical and Physical Analysis:

Horizon	Horizon Depth (cm)	pH (water)	pH (CaCl2)	EC dS/m	Sodium Chloride %	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-10	8.4	7.7	0.19		18.5	6	1.4	0.7
B21	10-30	9	7.9	0.3	<0.05	10.5	8.4	0.9	4.4
B22	30-60	9.2	8.7	1.12	0.2	6.7	12	1.1	8.2

Horizon	Horizon Depth (cm)	Total Nitrogen %	Oxidisable Organic Carbon %	Field Capacity pF2.5	Wilting Point pF4.2
A1	0-10	0.15	1.7	26.2	17.5
B21	10-30			31.7	22.6
B22	30-60

Management Considerations:

Surface (A) Horizon

• The surface soil is self-mulching which provides a good seed bed that is friable and easily worked. The surface becomes sticky when wet.

• The surface soil has a high inherent fertility (based on the sum of the exchangeable basic cations).

• Tillage or excessive trafficking should be avoided if the soil is wetter than the plastic limit. Such disturbance may result in soil structural degradation (eg. compaction, smearing) occurring. Ideally, tillage should take place when the soil is drier than the plastic limit down to at least the depth of tillage.

Subsoil (B) Horizons

• The top of the subsoil is strongly sodic but does not disperse (unless mechanically disturbed when moist). It is also strongly alkaline which indicates that certain nutrients may be poorly available to plants (eg. zinc, iron, copper and manganese).

• From 30 cm depth the subsoil is strongly sodic and strongly dispersive which will result in root and water movement being restricted. The level of soluble salts increases in this horizon which will restrict the growth of salt sensitive plants. Few roots were observable below 30 cm depth at the pit face.

Profile Described By: Mark Imhof, John Martin, David Rees, Sonia Thompson (May 1994).