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NE42

Property: Rutherglen Research InstitutePaddock #: 17
Aust. Soil Class.: Vertic (and Calcic), Mottled-Mesonatric, Grey SODOSOLNorthcote Factual Key: Dy 3.43
Great Soil Group: solodic soil
Map Unit: Black Dog fine sandy loam (n.b this soil profile more closely resembles Lilliput loam)
General Landscape Description: Lower part of plain (associated with Black Dog Creek).

Soil Profile Morphology:


Photo: Site NE42 Landscape
NE42 Landscape


Surface Soil

O0-1 cmOrganic mat; sharp change to:
Photo: Site NE42 Profile
NE42 Profile
A11-8 cmBrown (7.5YR4/4); fine sandy loam; weak coarse blocky structure; firm consistence dry; contains a common (15%) amount of ferro-manganiferous nodules (5-12 mm size); pH 4.9; abrupt change to:
A28-45 cmPinkish white (7.5YR7/4) con-spicuously bleached (10YR8/3d) loamy sand; structureless; weak consistence dry; pH 5.6; abrupt and wavy change to:
Subsoil
B2145-60 cmLight brownish grey (2.5Y6/2) with yellowish red (5YR5/8) and faint brownish yellow (10YR6/6) mottles; light medium clay; moderate coarse blocky, breaking to moderate medium blocky structure; strong consistence, moderately moist; contains a few (5%) ferromanganiferous nodules (10 mm size); pH 7.6; gradual change to:
B2260-75 cmLight brownish grey (2.5Y6/2) with faint brownish yellow (10YR6/6) mottles; light medium clay; weak coarse prismatic, breaking to strong coarse blocky structure; strong consistence, moderately moist; contains a common (10%) amount of manganese stains; pH 8.6; clear change to:
B2375-95 cmLight yellowish brown (2.5Y6/4) with olive yellow (2.5Y6/6) diffuse mottles; medium clay; moderate coarse prismatic, breaking to strong coarse blocky structure; strong consistence moderately moist; many slickensides present; pH 8.9; clear change to:
B31k95-120 cmPale brown (10YR6/3); medium heavy clay; strong very coarse prismatic structure; firm consistence moist; contains a few (2-5%) silica and carbonate nodules (2-50 mm size); pH 9.2; clear change to:
B32120-140 cmLight olive brown (2.5Y5/4); light medium clay; moderate coarse prismatic, breaking to moderate coarse blocky structure; very firm consistence moderately moist; pH 9.3; gradual change to:
B33140+ cmDark yellowish brown (10YR4/4); sandy clay loam; moderate coarse blocky structure; strong consistence moderately moist; contains a few (5%) manganese stains; pH 9.3;

Key Profile Features:

  • Strong texture contrast between surface (A) horizons (<10 % clay) and subsoil (B21) horizon (47 % clay)
  • Conspicuously bleached subsurface (A2) horizon.
  • Vertic properties (ie. slickensides present) in deeper subsoil.
Soil Profile Characteristics:

Graph: pH levels in Site NE42



The surface horizon is very strongly acid. The subsurface (A2) horizon is moderately acid. The upper subsoil is slightly alkaline and the deeper subsoil becomes very strongly alkaline.

Graph: Salinity levels in Site NE42



The salinity rating is very low for the upper profile and becomes low at about one metre depth.

Graph: Sodicity levels in Site NE42



The subsoil is strongly sodic throughout. Strong to complete dispersion occurs.

Graph: Clay% in Site NE42



The clay percentage increases significantly at the A/B horizon interface.



Horizon
Horizon Depth
(cm)
pH
(water)
pH
(CaCl2)
EC 1:5
Organic Carbon
G/100g
Exchangeable Cations
Ca
Mg
K
Na
meq/100g
A1
1-8
4.9
4.1
0.12
1.1
0.25
0.51
0.14
A2
8-45
5.6
4.4
<0.05
0.28
0.08
0.18
0.06
B21
45-60
7.6
6.1
0.06
3.8
6.5
0.53
1.8
B22
60-75
8.6
7.1
0.11
4.6
9.7
0.61
2.9
B23
75-95
8.9
7.5
0.09
5.3
13
0.6
4.5
B31k
95-120
9.2
8.2
0.3
5.6
14
0.6
4.9
B32
120-140
9.3
8.2
0.23
7.3
12
0.82
3.9
B33
140+
9.3
7.9
0.12
3.8
7.7
0.41
2.8

Horizon
Horizon Depth
(cm)
Exchangeable Aluminium
mg/kg
Exchangeable Acidity
meq/100g
Field Capacity
pF 2.5
Wilting Point
pF 4.2
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
1-8
55
19.5
5.3
17
54
16
9
A2
8-45
17
15.4
1.7
19
60
16
5
B21
45-60
30.6
18.8
11
32
9
47
B22
60-75
33.8
18.5
6
33
11
50
B23
75-95
B31k
95-120
B32
120-140
B33
140+

Management Considerations:

Whole Profile

  • Plant available water capacity (PAWC) is considered to be low (estimated at 80 mm) for the top metre of the soil. This is based on available laboratory data. Effective rooting depth is, however, likely to be significantly lower than 1 metre in this profile due to the strongly sodic subsoil conditions. Therefore, PAWC is likely to be very low.
Surface (A) Horizons
  • In very strongly acid soils, manganese and aluminium solubility can increase to toxic levels. The level of exchangeable aluminium measured in the laboratory is, however, only moderate (55 ug/g) and unlikely to significantly restrict the growth of aluminium sensitive species. A pH/aluminium test performed on a bulked sample (taken across the paddock) would be most appropriate.
  • The hardsetting surface soil has a high fine sand and silt content (70 %). Organic matter is therefore very important for maintaining aggregation and preventing slaking. Cultivation in a dry condition can be deleterious to soil structure as the soil will become 'powdery' and subsequent rainfall may result in surface sealing occurring.
  • Both surface horizons have a very low nutrient status (based on the sum of the exchangeable basic cations).
  • The subsurface (A2) horizon will become 'soupy' when waterlogging occurs on top of the poorly permeable subsoil. This is because of the very high fine sand and silt content and resultant low liquid limit which gives little cohesive strength when saturated.
  • The relatively low wilting point value (ie. 5%) indicates that plants will be able to utilise light rains falling on relatively dry soil.
Subsoil (B) Horizon
  • The subsoil is strongly sodic (and has a low calcium:magnesium ratio) and disperses completely. As a result, subsoil permeability will be very low and aeration will also be restricted.
  • The deeper subsoil displays vertic properties (ie. presence of slickensides). This indicates that significant shrinking and swelling occurs in the deeper subsoil.
  • Manganese segregations in the subsoil may have a toxic effect on sensitive species.
Management Details:
  • Cultivated (1977), disc cultivated (1984)
  • Topdressed with 1t/ha lime (1984) and 29 bags super, lime and Mo in 1986.

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