Friends of Werakata National Park
Banksia Spinulosa


The soils within the National Park tend to be of low to moderate fertility. They are generally acidic with pHs of the topsoils in the range 5.5 to 6.5. Soil types reflect the claystone types beneath. In the northern part of Werakata National Park predominant soils are Yellow Podzolic (Dy3.11) and Red Podzolic (Dr2.21, Dr3.11, Dr3.21). To the south the soil types include Chocolate Soils (Dr4.11, Dr4.51), Yellow Podzolics (Dy4.51), and Yellow Earths (Gn2.22).

      These Yellow Podzolic soils are claasified as Yellow Duplex soils as they have yellow to yellow-grey clayey subsoils.

  • Dy3 soils grey to grey-brown surface soils varying from loamy sands to clay loams. The surface soill sets hard when dry. They have a fairly sharp demarcation to a yellow-brown to grey-brown clay subsoil. Ironstone and/or quartz gravel and rock fragments are often present on the surface or in the upper layers. The surface of these soils is often permeable, but the subsoils are less so, leading to partial saturation of the upper soil in prolonged wet conditions. Phosphours and nitrogen levels tend to be very low.
      These Red Podzolic and Chocolate soils are classified as Duplex textured soils with red-brown to red clayey subsoils. They tend to be of moderate fertility, moderate water permeability, have good water storage abilities and good drainage. Most are low in potassium and nitrogen.
  • Dr2.21 soils are Hard Red Duplex soils. They tend to have reasonable potassium levels but low potassium and nitrogen. Subsurface soil tends to be light coloured but not bleached.
  • Dr3 soils are Hard Mottled-Red Duplex soils. They are similar to the Dr2 soils but tend to be mottled in appearance in the subsoils. They tend to be less water permeable and the subsoil can be more readily waterlogged in heavy rainfall conditions than Dr2 soils. they are also ore likey to have water run off the surface than in Dr2 soils.
  • Dr4 soils are classified as Friable Red Duplex soils. There topsoil tends to be very dark very structured and friable. they show a clear demarcation to a red-brown well structured clay subsoil. These soils are water permeable and well drained and exhibit moderate to high fertility. They do not have high reserves of phosphates or nitrogen.
      The Yellow Earths of the Gn2.2 type are characterized by graded patterns of change in the soil and earthy subsoils. They have carbonates only in the subsoil. They tend to have grey/brown/yellow sandy to loamy topsoils fading to a lighter colour beneath which grades into a yellowy massive/porous sandy clay loam followed by a clay subsoil. Permeability is moderate. Fertility tends to be low, with low levels of nitrogen, potassium and phosphorus common.

Factors Effecting Soils

    Human Factors
  • Fire
    Fire reduces the organic matter (humous) in the topsoil. It can increase erosion and loss of nutrients via wind and water. Leaching of nutrients can be increased. Fires temporarily increase the rainwater runoff potential.
  • Timber Harvesting
    The removal of timber causes a loss of biomass and thus carbon and nutrients from the ecosystem. Clear-felling, which has not been practiced whilst these areas have been State Forests or National Park, significantly increases the potential for erosion.
  • Roads
    The construcion of roads increases erosion.
    Natural Factors
  • Rainfall
    Rainfall adds some dissolved nutrients to the soils. It also causes some erosion of rocky exposures, and washes matter off vegetation. It also causes some leaching of solutes from the upper soil layers and can move nutrients, soils and vegetable matter.
  • Erosion
    A natural forest is an excellent protection against erosion. Areas of erosion within the Werakata National Park tend to be in areas previously altered by European occupation or by logging or grazing activities.
  • Animals
    Animals play a part in the formation of the soils by speeding up the conversion of plant material into humous. Animal manures can be rich in nutrients, and urines are a particularly rich source of soluble nitrogen (as urea). Soil formation is engendered not only by direct ingestion and digestion of plant material but also a number of species (eg galahs, cockatoos, white ants, caterpillars) are responsible for bringing plant material down to soil level before its "natural" death. Other creatures are responsible for the degradation of the dead material and accelerate the production of soil eg worms, borers, white ants.
  • Plants
    Inorganic substances in the soils are cycled through plants and animals and eventually return to the soils. "Dust to dust, ashes to ashes". The plants protect the soils from erosion, and decaying plant material provides humous, which insulates the soil from harsh temperatures. Humous also significantly reduces evaporation and increases soil permeability and water storage capacity. Plant roots have a binding effect to contribute to soil stability. Organic material in the soil also serves as a reservoir of nutrients for the soil.

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