GN28

GN28 Landscape

A11	0-5 cm	Dark brown (10YR4/3) loam, fine sandy; abundant plant roots (> 50%); clear change to:	GN28 Profile
A12	5-12 cm	Dark yellowish brown (10YR4/4) [sporadically bleached in patches] clay loam; rusty root channel mottling present; weak coarse blocky structure; firm consistence, slightly moist; contains many (20 - 30 %) ferromanganiferous nodules and concretions (5 -10 mm size); rusty root channel mottling present; pH 6.5; abrupt and wavy change to:
Subsoil
B21	12-45 cm	Yellowish brown (10YR5/4 and 5/6) medium clay; moderate coarse blocky structure; strong consistence, slightly moist; contains very few (2 %) manganese stains; pH 7.4; clear change to:
B22	45-90 cm	Yellowish brown (10YR5/6 and 6/6) medium clay; moderate coarse blocky, breaking down to moderate fine polyhedral structure; strong consistence, slightly moist; contains few (5-10 %) manganese stains and a trace amount of soft carbonate; pH 7.8; clear change to:
B23	90-120 cm	Light olive brown (2.5Y5/4) medium clay; strong fine polyhedral, breaking down to strong very fine polyhedral structure; pH 8.5.

• Strong texture contrast between surface (A) horizons and subsoil (B21).

	pH	Salinity Rating	Sodicity	Dispersion
Surface soil (A1 horizon)	Slightly Acid	Very Low	Sodic	None
Upper subsoil (B21 horizon)	Slightly Alkaline	Very Low	Non-Sodic	Moderate1
Deep subsoil (at 1 m)	Strongly Alkaline	Very Low	Sodic	-

Management Considerations:

Surface (A) Horizons

• The surface soil has a high fine sand (36%) and silt (33%) content. Organic matter is important for maintaining soil aggregation for such soils. Reduction in organic matter levels due to cultivation will promote slaking and resultant surface sealing; restricting infiltration and plant emergence.

• The upper subsoil is non-sodic, but does disperse (although not strongly). This may occur due to the high levels of exchangeable magnesium (ie. 39 %) and indicates that some restriction to water and root movement will occur. The presence of rusty root channel mottling in the surface horizon suggests that some restricted drainage occurs in the soil profile. The subsoils of Goulburn loam soils are generally regarded as having poorer drainage characteristics than Lemnos loam subsoils.