LP122

Soil Profile Morphology

Surface Soil

A1	0-10 cm (to 25 cm in some places)	Dark reddish brown (5YR3/4), sandy clay loam; very firm consistence when moderately moist; pH 6.2; sharp change to:	LP122 Profile
Subsoil
B21	10-30 cm	Dark reddish brown (5YR3/3), medium clay; moderate coarse blocky structure; very firm consistence when moderately moist; pH 7.7; gradual change to:
B22	30-80 cm	Yellowish red (5YR4/6), medium clay; moderate coarse polyhedral structure; firm consistence when moist; pH 8.9; clear and wavy change to:
Bk	Band of carbonates, soft and hard runs diagonally across profile from 35cm to 100cm.
B23	80-120 cm	Dark brown (10YR4/3) with yellowish red (5YR4/6 & 5YR5/8) mottles, light medium clay; moderate coarse polyhedral structure breaking to strong fine polyhedral structure; very firm consistence when moist; gypsum crystals present in top 10 cm of this horizon; occasional hard carbonate; pH 9.1.

• Texture contrast between surface (A) horizon and subsurface (B) horizons.
• Carbonate band (10 cm) runs roughly diagonally across the pit face from about 35 cm to 100 cm depth.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	very low	sodic	moderate dispersion1
Subsoil (B21 horizon)	slightly alkaline	very low	sodic	slight dispersion1
Deeper subsoil (at 80 cm)	strongly alkaline	very low	sodic	none1
1 Strong to complete dispersion when the aggregate is remoulded.

Management Considerations:

Whole Profile

• The whole 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 horizon (as it is 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 horizon has a low inherent fertility (based on the sum of the basic exchangeable cations).
• 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 on soils such as these with such a high fine sand content. 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.

• Concentrated carbonate band (about 10 cm thick) runs diagonally across all horizons between 35 cm and 100 cm.
• The deeper subsoil (from 30 cm depth) is strongly alkaline which indicates that some nutrients (eg. copper, iron, manganese, and zinc) may be poorly available to deeper rooted plants.

• Profile described by Paul Rampant and Ruth Lourey (23/5/96)