LP117

LP117 Landscape

Soil Profile Morphology

Surface Soil

A1	0-8 cm	Dark yellowish brown (10YR4/4), sandy clay loam; weak blocky structure; very firm consistence when dry; pH 6.4; abrupt change to:	LP117 Profile
A3	8-15 cm	Dark yellowish brown (10YR3/4), heavy sandy clay loam; strong consistence when moderately moist; pH 6.8; abrupt change to:
Subsoil
B21	15-35 cm	Dark brown (10YR3/3), medium heavy clay; weak very coarse blocky structure, breaking to strong coarse blocky structure; firm consistence when moist; slickensides evident from 30 cm down; pH 7.6; gradual change to:
B22	35-70 cm	Yellowish brown (10YR5/6), medium clay; strong coarse blocky structure, breaking to moderate medium sized polyhedral structure; firm consistence when moist; very few (>1%) hard carbonate nodules; pH 8.6; clear and wavy change to:
B23	70-100 cm	Yellowish brown (10YR5/8), medium clay; weak coarse polyhedral structure, breaking to strong medium sized polyhedral structure; weak consistence when moist; few soft and hard carbonates (5%); pH 8.5; clear and wavy change to:
B24	100-120 cm	Dark yellowish brown (10YR4/4), medium clay; moderate coarse prismatic structure, breaking to strong medium sized polyhedral structure; up to 10% manganese stains in the upper part of this horizon; pH 8.6.

• Strong texture contrast between surface (A) horizons and subsoil (B) horizons.
• Vertic properties (slickensides) throughout the subsoil.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	very low	sodic	moderate
Subsoil (B21 horizon)	slightly alkaline	very low	strongly sodic	complete
Deeper subsoil (at 100+ cm)	strongly alkaline	low - medium	sodic	slight

Management Considerations:

Whole Profile

• The entire profile is sodic and dispersive which will result in restricted root and water movement in the soil. Water is likely to build up on the surface and in the surface horizons (as they are more porous) after heavy rains causing waterlogging and surface runoff. The addition of gypsum may ameliorate this problem. A test strip could be used to assess the likely benefits.

• The surface being dispersive will be affected by disturbance (ie cultivation, overstocking) in a moist condition and may even be affected by the action of rain on the surface of the soil. These actions may exacerbate the hardsetting condition of the soil. This may result in surface sealing which will reduce water infiltration and seedling emergence.
• Organic carbon levels show that organic matter content is low for the surface soil from this pit. Organic matter is important for enhancing soil aggregation, fertility and water holding capacity. Organic matter levels will build up under pasture but will decline if cultivation takes place. Practices such as residue retention, minimum tillage and including pasture rotations should be utilised if cropping occurs.
• The surface horizons have a low inherent fertility (based on the sum of the basic exchangeable cations).

• The subsoil displays vertic properties (ie. slickensides) which indicates that significant shrinking and swelling occurs in the deeper subsoil. This may have implications for engineering purposes (eg. disturbance to fencelines).
• The deeper subsoil (from 35 cm depth) is strongly alkaline which indicates that some nutrients (eg. copper, iron, manganese, and zinc) may be poorly available to deeper rooted plants.
• Deep subsoil (below 70 cm) is slightly saline.

• Waterlogging a problem in this paddock.
• Floods every 2-3 years.
• Agisted cattle caused pugging last year.
• Oats sown over subclover as standing feed.

• Profile described by Paul Rampant and Ruth Lourey (22/5/96)