Back to: Victorian Horticulture Soils
|Ferrosols (formerly referred to as ‘krasnozems’) are deep red friable soils that lack strong texture contrast between surface (A) horizons and the upper subsoil (B21) horizon.
They are characterised by relatively high levels of free iron oxide (i.e. free iron oxide content greater than 5%) and are generally strongly acid in the upper soil profile.
Example Ferrosol soil profile at Ellinbank in West Gippsland
|Ferrosols are a major horticulture cropping soil that generally occur in higher rainfall areas and are usually associated with older basaltic landscapes.
Red Ferrosols are common in the West Gippsland region, where they are associated with the rolling basalt (referred to by geologists as ‘Older Volcanic’) hills in the Warragul, Thorpdale, Leongatha and Neerim South areas. They are typically generally strongly acidic throughout, lack strong texture contrast and are high in free iron oxide. Mainly Red Ferrosols have been described in Gippsland, but some Brown and Yellow forms occur in less well-drained landscape positions. Soil Pit Site GP15 is an example of a Red Ferrosol at Ellinbank.
|Red Ferrosols also occur along the Great Divide in central Victoria, between Ballarat and Castlemaine, on volcanic plains and vents. In north-east Victoria they mainly occur in the King Valley region. Ferrosols also occur along parts of the Mt Camel Range where they have developed on Cambrian greenstone. Soil Pit Site LP99 is an example of a Red Ferrosol on the Mt Camel Range near Colbinabbin.
Aerial image of cropping at Thorpdale
|Ferrosols have high levels of free iron oxide which gives them a high degree of structural stability. Due to their high iron oxide contents these soils tend to "fix" phosphorus which makes it less available to plants. Regular phosphorus application will assist in overcoming such a deficiency. Addition of molybdenum may also be required. Zinc and copper can also be 'fixed' by high iron oxide contents.
These soils are deep and very well drained due to their strongly developed structure and lack of strong texture contrast between surface and subsoil horizons. Water infiltration rates will be high unless significant compaction has occurred.
|Red Ferrosols generally have high organic matter levels, which enhances soil fertility and aggregate stability. When intensively cropped, organic matter levels will decline and this will result in some structural degradation and fertility decline. Studies have shown that organic matter is an important source of nitrogen, phosphorus and sulphur in such soils. Organic matter levels can be improved by utilising green manure crops, crop residue retention, minimal cultivation and pasture rotations. Management practices which result in increased organic matter levels include: minimum tillage; growing green manure crops (e.g. annual ryegrass, sorghum, oats, lupins); incorporating pasture phases in crop rotations, and retaining and incorporating crop residues (Cotching 1995).