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LP9

Group: Middle Creek Landcare GroupAustralian Soil Classification: Hypercalcic, Subnatric, Red SODOSOL
Northcote Factual Key:Dy 2.43 Great Soil Group: solodized solonetz
General Landscape Description: Upper slope on western side of a sedimentary (lower Ordovician) hillslope. Yellow Gum (E. leucoxylon) and Grey Box (E. microcarpa) association is the typical native vegetation.

LP9 Landscape
LP9 Landscape


Soil Profile Morphology

Surface Soil

A10-5 cmDark brown (10YR3/3) light fine sandy clay loam; weakly structured; firm consistence dry; contains occasional shale fragments; pH 5.5; sharp and irregular change to:
LP9 Profile
LP9 Profile
A25-10 cm Light brown (7.5YR6/4) conspicuously bleached fine sandy clay loam; weakly structured; strong consistence dry; contains a slight (10%) amount of ferruginous nodules (buckshot); pH 6.5; sharp and irregular change to:
Subsoil
B2110-25 cmYellowish Red (5YR5/8) heavy clay; moderate coarse columnar, breaking down to strong coarse blocky structure (with smooth faced peds); very strong consistence moist; contains occasional shale fragments; pH 7.1; sharp and wavy change to:
B2225-40 cmRed (2.5YR4/8) heavy clay; strong medium blocky structure; very strong consistence moist; contains occasional shale fragments; pH 8.6 :
B3k40-100 cmStrong brown (7.5YR4/6) medium clay; with a heavy (>50%) amount of soft carbonate together with weathered shale; pH 9.3; gradual change to:
C100+ cmLaminated soft shale.

Key Profile Features
  • Strong textural contrast between A horizon and clay B horizons.
  • Sodic subsoil.
  • Increasing pH with depth down the profile.

Key Profile Characteristics

pH
Salinity Rating
Surface
(A1 horizon)
strongly acid
very low
non-sodic
water-stable
Subsoil
(B21 horizon)
slightly alkaline
very low
sodic
strong
Deeper subsoil
(at 1 m)
very strongly alkaline
low
strongly
sodic
strong

LP9 Graphs


Management Considerations:

Surface (A) horizons

  • The surface horizon has high levels of organic carbon and total nitrogen and a moderate overall nutrient status. However, being very shallow (i.e. 5 cm deep) it provides a limited rooting environment above the sodic subsoil.
  • The high organic matter levels ensure that the surface aggregates are water-stable and will not readily break down when wet.
  • Aluminium and manganese toxicity can occur in strongly acid surface soils, although exchangeable aluminium and manganese levels appear relatively low at this site. A lime test (sampled at the paddock level) may be appropriate to determine whether lime is needed to raise the pH levels.
  • The conspicuously bleached A2 horizon indicates that periodic waterlogging may occur. This horizon has low fertility and is likely to become "soupy" when worked in a wet condition (as is evident by strong dispersion occurring after remoulding).

Subsoil (B) Horizons
  • The coarsely structured and dense subsoil (i.e. B21 horizon) is sodic and becomes strongly sodic with increasing depth down the profile. Strong dispersion occurs as a result, creating conditions which will restrict water and plant root movement.
  • Effective plant rooting depth is shallow due to the coarsely structured sodic subsoil being encountered at 10 cm depth. Plant available water capacity for the profile is also low as a consequence.
  • At a depth of 40 cm the soil becomes strongly alkaline which may result in nutrients such as phosphorous, iron, manganese and zinc becoming poorly available to plants.

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