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LP50

Property: LP50 MitiamoGroup: Pine Grove Farm Advance
Australian Soil Classification: Epicalcareous-Endohypersodic, Epipedal, Red VERTOSOL, intermixed with a Black VERTOSOLNorthcote Factual Key: Ug 5.3
Great Soil Group: brown clay
General Landscape Description: Edge of an old alluvial plain (treeless) near Mount Terrick Terrick. This site occurs in a slight depression. Gilgai microrelief existed prior to clearing.

Photo:  Landscape photo - Mitiamo soil pit LP50
LP50 Landscape

Soil Profile Morphology

Surface Soil
A10-10 cmDark reddish brown (5YR3/3); light medium clay; surface flake; moderate fine to medium polyhedral structure; very firm consistence dry, friable moist; pH 8.3; sharp change to:
Photo:  Profile photo - Mitiamo soil pit LP50
LP50 profile
Subsoil
B2110-35 cmYellowish red (5YR5/6); medium clay; cracking occurs to the base of this horizon; weak coarse blocky structure; strong consistence dry; pH 8.5; gradual and wavy change to:
B22k35-100 cmReddish brown (5YR4/4); medium heavy clay; moderate prismatic, parting to coarse blocky structure (with smooth-faced peds); very strong consistence dry; fine-earth carbonate common (10-15 %); pH 9.3; gradual change to:
B23100 cm+Yellowish red (5YR5/6); heavy clay; moderate coarse blocky structure; strong consistence moist; pH 9.5.

NOTE
: The subsoil (B21 horizon) colour varies at this site. It can also be greyish brown (10YR3/2) and extend to a depth of about 80 cm.

Key Profile Features
  • Clay texture throughout the profile.
  • Strong profile cracking during wetting and drying cycles

Key Profile Characteristics

pH
Salinity Rating
Surface
(A1 horizon)
moderately alkaline
very low
non-sodic
none
Subsoil
(B21 horizon)
moderately alkaline
very low
non-sodic
none
Deeper subsoil
(at 1 m)
extremely alkaline
low-medium
strongly sodic
moderate

LP50a
Horizon
Horizon Depth
pH (water)
EC 1:5
NaCl
Exchangeable Cations
Ca
Mg
K
Na
meq/100g
A1
0-10
8.3
0.15
28
3.9
2.2
0.2
B21
10-35
8.5
0.12
24
7.4
1.2
0.9
B22k
35-100
9.3
0.29
<0.05
14
15
0.9
4.1
B23
100+
9.5
0.78
0.09
6.2
18
1.3
10

Horizon
Horizon Depth
Ex Al
mg/kg
Ex Ac
meq/100g
Field
pF2.5
Wilting Point
pF4.2
Coarse Sand
(0.2-2.0mm)
Fine Sand
(0.02-0.2mm)
Silt
(0.002-0.02mm)
Clay
(<0.002mm)
A1
0-10
33.5
25.4
7
22
10
52
B21
10-35
42.3
32.2
7
17
7
61
B22k
35-100
49.1
37
5
12
6
57
B23
100+
LP50b
Horizon
Horizon Depth
pH (water)
EC dS/m
NaCl
Exchangeable Cations
Ca
Mg
K
Na
Meq/100g
B21
10-40
8.6
0.12
26
5.9
1
0.7
B22
40-80
9.2
0.3
<0.05
18
10
0.8
5.1

Horizon
Horizon Depth
Ex Al
mg/kg
Ex Ac
meq/100g
Field
pF2.5
Wilting Point
pF4.2
Coarse Sand
(0.2-2.0mm)
Fine Sand
(0.02-0.2mm)
Silt
(0.002-0.02mm)
Clay
(<0.002mm)
B21
10-40
40.5
30.7
B22
40-80

Management Considerations:
  • In general, management strategies for all soils should aim to increase organic matter levels in the surface soil; minimise the degradation of soil aggregates and porosity; promote the development of stable biopores; improve the calcium status of the ion exchange complex (particularly when sodium is a significant part – i.e. sodic), and break up any hardpans. Less frequent tillage; using less aggressive implements, and working the soil at optimum moisture conditions can all assist in maintaining soil aggregation and porosity as well as reducing the breakdown of organic matter. Practices such as residue retention, minimum tillage and including pasture rotations could be utilised if cropping takes place in order to build up organic matter, reduce erosion risk and increase fertility.
  • Plant available water capacity (PAWC) is estimated to be medium (estimated at 100-120 mm) for this profile - based on the laboratory data available.

Surface (A) Horizons
  • The surface horizon has a very high overall nutrient status.
  • When the soil is dry, heavy rains will move down soil cracks. This rapid recharge can be valuable for the survival of plants near wilting. When wet, the soil will swell and further infiltration of water will be relatively slow.
  • Tillage of cracking clay soils should be avoided if the soil is wet (i.e. wetter than the plastic limit). At such moisture conditions, tillage or excessive trafficking or overstocking could result in structural damage (e.g. compaction, smearing) occurring. Ideally, tillage and trafficking should take place on cracking clay soils when the soil is drier than the plastic limit, down to at least the tillage depth.
  • The high wilting point (25%) value indicates that plants will not be able to fully utilise light rains falling on relatively dry soil, as there will be insufficient moisture to wet the soil above the wilting point. This may result in moisture stress to plants in a dry spring.

Subsoil (B) Horizons
  • The subsoil becomes sodic below 35 cm but does not disperse unless it is remoulded.
  • Soluble salts are low for the top metre of the profile.
  • Below 35 cm depth the profile becomes very strongly alkaline, indicating that certain nutrients (e.g. phosphorus, iron, manganese and zinc) may become poorly available to plants.

Landholder Comments:
  • Gypsum has never been used.
  • This paddock yields higher than Site LP51.
  • Wheat is cropped here.

Notes:
Profile described by Mark Imhof, Paul Rampant and Karen de Plater (1/3/95)
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