Features of black Dermosols on Tocal:

  • formed on lower slopes and plains from colluvium (material that has been moved downslope) or alluvium (material deposited by stream flow). This profile is an example of Basaltic colluvium.
  • moderately well to imperfectly drained
  • gradational profiles with structured B2 horizon
  • deep humic topsoil which is acid
  • weakly weathered and weakly leached - pH increases with depth.

Calving paddock has a deep humic topsoil common of the Black Dermosols on Tocal. CEC levels are higher in this profile that those of the Rudosol soils, reflecting a higher clay content and a likely presence of shrinking and swelling clays.

Calving paddock shows a strongly acid topsoil horizon associated with high aluminium levels. The levels of exchangeable calcium and magnesium at depth are derived from the weathering of plagioclase felspars and ferromagnesium minerals in the basaltic parent material.

Available phosphorus is deficient in Calving paddock which can be highly productive if phosphorus levels are kept high. This paddock lends itself to pasture improvement due to the slight slope and the open nature of the landscape. This is among the most intensively-used soils for beef grazing at Tocal.


Profile description

  • 0cm: A horizon.Very dark grey-brown clay loam.with fine crumb structure. Surface soil hard. Plant roots abundant. Drainage good. pH 4.5
  • 12cm: B1 horizon.Very dark grey to black light medium clay. Slight amounts of angular gravel. Large angular fragments of volcanic rock. Cultivation has mixed the colluvial gravel with the soil. Structure is fine crumb. Drainage good. Plant roots common. Note large horizontal tree root at 21 cm.
  • 25cm: B2 horizon.Very dark grey to black heavy clay. Fine crumb structure. Drainage fair. Plant roots common. Burnt soil found at 30cm. pH 5.8
  • 49cm: B2/C horizon. Dark yellow-brown and very dark grey heavy clay. Clay cracks when dry. Angular blocky structure. Plant roots common. Drainage fair. pH 6.6.
  • 75cm: C horizon. Very dark brown sandy clay with yellow fragments of deeply weathered rock. Note lime concretions up to 10mm diameter. Massive structure. 8mm horizontal tree root at 70cm. Few if any other plant roots. pH7.0.

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