LS13b

Location: Netherby

Australian Soil Classification: Vertic, Pedal, Calcic, CALCAROSOL

Northcote Factual Key: Gc2.2


General Landscape Description: Gently Undulating Plain near footslopes of Gently Undulating Rises unit. In a relatively low lying area in association with Grey Vertosols.
Site Description: Cropping. Gilgai micro-relief occurs.
Native Vegetation: Black Box (Eucalyptus largiflorens) is the natural vegetation.

LS13b Landscape

Soil Profile Morphology:

Surface Soil .

A1	0-10 cm	Very dark greyish brown (10YR3/2); fine sandy clay loam; weakly structured; firm consistence dry; pH 8.5:	LS13b Profile
Subsoil
B1	10-15 cm	Dark grey (10YR4/1); fine sandy light clay; weak coarse subangular blocky blocky structure; firm consistence dry; pH 8.6:
B21	15-35 cm	Dark grey (10YR4/1); heavy clay; moderate coarse prismatic, breaking to strong coarse blocky structure; very firm consistence dry; pH 9.2; clear boundary change to:
B22	35-70 cm	Greyish brown (10YR5/2); heavy clay; moderate coarse prismatic, breaking to moderate coarse blocky structure; weak consistence moist; contains few (2 - 10%) soft carbonate segregations; pH 9.7; gradual change to:
B23	70+ cm	Light grey (10YR7/2); heavy clay; pH 9.8

Key Profile Features:

• Gradual increase in soil texture to heavy clay subsoil.
• Vertic properties in deeper subsoil.

Soil Profile Characteristics:

-	pH	Salinity	Sodicity	Dispersion
Surface (A1 horizon)	Moderately Alkaline	Low	Non-Sodic	Slaking, No dispersion1
Subsoil (B21 horizon)	Very Strongly Alkaline	Low	Sodic	Slight 2
Deeper Subsoil (at 70 cm)	Extremely Alkaline	Medium	Strongly Sodic	_

¹ Moderate dispersion after remoulding. ² Strong dispersion after remoulding.

The surface soil is moderately alkaline. The subsoil is very strongly alkaline becoming extremely alkaline with depth.

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

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

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	8.5	7.8	0.12		18.9	4	2	0.2
B1	10-15	8.6	7.9	0.14		19.9	5.8	1.9	0.7
B21	15-35	9.2	8.3	0.34	<0.05	15.7	12	1.7	4.5
B22	35-70	9.7	9	0.82	0.08	4.5	13	1.5	8.6
B23	70+	9.8	9.1	0.82	0.11	3.1	12	1.5	10.6

Horizon	Horizon Depth (cm)	Total Nitrogen %	Oxidisable Organic Carbon %	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) %
A1	0-10	0.12	1.2	21	15.1	20	27	8	36
B1	10-15			31.7	19.8
B21	15-35					22	23	7	34
B22	35-70
B23	70+

Management Considerations:

Surface (A) Horizon

• Surface and subsurface horizons (ie. to a depth of 15 cm) are non-sodic but will slake when rapidly wet. Improving organic matter levels will help reduce slaking. Practices which result in increased soil organic matter levels (eg. direct drilling, stubble retention, including pasture rotations) should be utilised.
• The surface soil disperses after remoulding which indicates that disturbance to this horizon (eg. cultivation) whilst in a moist to wet condition can result in structural degradation.

Subsoil (B) Horizons

• The coarsely structured upper subsoil is sodic and disperses slightly. This may result in conditions which restrict root and water movement into the subsoil.
• The very strongly alkaline subsoil (below 30 cm depth) indicates that nutrients such as iron, manganese, copper and zinc may be poorly available to plants at depth.
• Soluble salts may cause problems to sensitive crops (e.g. chickpeas and other legumes) from 35 cm and below. On the pit face many roots were present (mainly along ped faces) down to 35 cm.

Comments from Landholder:

• Land cleared in 1880.
• Direct drilling used as cultivation method.
• Superphosphate and nitrogen applied.
• Continuously cropped since 1989 with grains (wheat, barley) and legumes (chickpeas, faba beans).

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