Corangamite Region   'Brown Book'   - How to optimise your soils to enhance productivity
What do dominant weeds tell us about soil conditions?
Key Points

Weeds present in the Corangamite region grouped by type Resources

Source: A.J. Brown
Key Points
  • Most weeds are symptoms of the paddock and are often referred to as indicator species in pasture
  • They can indicate soil-related problems such as lack of fertility, poor soil structure, acidity, poor drainage and salinity

  • Many weeds are competitive in acid soils
  • Some weeds are reduced when fertiliser is regularly applied, particularly phosphorus
Weeds present in the Corangamite region grouped by type
Low fertility weed species
Indicator of infertile, poorly structure soils which are often waterlogged

Bent grass (Agrostis capillaris)
  • Most common type in south west Victoria
  • Invasive on low fertility, low nitrogen, acid soils in higher rainfall areas where pastures are under utilised in late spring
  • Can be managed by increasing soil fertility utilising the excess spring/summer production, rotational grazing and occasionally spray topping

  • More information about Bent Grass
    Figure 1 - Brown top bent grass - Photo: Mark Imhof, DEPI

Sweet vernal (Anthoxanthum odoratum)
    Figure 2 - Flower-head of Sweet Vernal-grass - Photo: A J Brown

Fog grass (Holcus lanatus)
  • Particularly tolerant of acid soils with low fertility
  • Increased drainage, fertiliser use and heavy grazing are the best ways to reduce fog grass
  • Stock avoid grazing it due to low palatability

  • More information about Fog Grass
    Figure 3 - Flower-heads of Yorkshire Fog - Photo: A J Brown
  • In weak pastures caused by soil acidity and low fertility, especially potassium and phosphorus
  • Will tolerate a wide pH range
    Figure 4 - Sorrell - Photo: Javier Martin (Own work) via Wikimedia Commons

Onion grass (Romulea rosea)
    Figure 5 - Onion grass plant - Photo: Mark Imhof, DPI

Dandelion (Taraxacum spp.)
    Figure 6 - Dandelion plant - Photo: A J Brown

Flat weed (Hypochoeris radicata)
    Figure 7 - Flowering plant of Flatweed or Cat's ear- - Photo: A J Brown
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Early germinating annual grass weeds
Some prefer high soil fertility (barley grass) but silver grass is insensitive to fertility

Barley grass (Hordeum leporinum)
    Figure 8 - Mediterranean Barley-grass - flower spikes - Photo: A J Brown

Silver grass (Vulpia spp.)
    Figure 9 - Flower-head of Squirrel-tail Fescue or Silver Grass - Photo: A J Brown
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Late germinating weed species of new pastures
  • Require fine, light, overworked bare soil in cold and wet conditions
  • Will become more prevalent if pasture is sown late in infertile soil and if the soil becomes waterlogged
Winter grass (Poa annua)
    Figure 10 - Poa annua or Winter Grass - Photo: Forest & Kim Starr via Wikimedia Commons

Toad rush (Juncus bufonius)
    Figure 11 - Toad Rush in flower - Photo: A J Brown
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High fertility weed species
Require high soil nitrogen and thrive where soils are fertile

Capeweed (Arctotheca calendula)
  • Usually dominates paddocks which are bare in autumn, have high soil fertility and few perennial grasses
  • Common on high fertility sites such as stock camps and gateways

  • More information about Capeweed
    Figure 12 - Capeweed plants - Photo: A J Brown
Corkscrew (Erodium spp.)
  • Usually dominates paddocks which are bare in autumn, have high soil fertility and few perennial grasses
  • Occurs on well drained, dry slopes, particularly light textured soils

    Figure 13 - Corkscrew/Erodium spp - Photo: Forest & Kim Starr via Wikimedia Commons

Chickweed (Cerastium glomeratum)
    Figure 14 - Mature plants of Mouse-eared Chickweed - Photo: A J Brown

  • Thistles
    • Indicate high soil nitrogen levels but in some basalt soils they can be a problem even if clover is not dominant
    • Occur after cropping/cultivation of soil
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Dormant-seeded summer annual weeds
Thrive on very bare ground

Goosefoot (Chenopodium glaucum)
    Figure 15 - Glaucous Goosefoot plant - Photo: A J Brown
Fat hen (Agrostis capillaris)
  • Plants have produced 500,000 seeds and seeds have been known to survive for 30 to 40 years in the soil
  • It grows on many soil types but grows to its greatest size on fertile, heavy soils
  • Mainly seen in response to summer rainfall

  • More information about Fat hen
    Figure 16 – Fat Hen toothed leaves - Photo: G. Sainty

Wild radish (Raphanus raphanistrum)
  • Grows over a range of soil types but prefers slightly acidic, fertile soils with a high level of nitrogen
    Figure 16 - Wild radish in a canola crop at flowering - Photo: Andrew Storrie

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Other weeds
  • Rushes
    • Indicator of waterlogged soils
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Brown Book content has been based on published information listed in the Resources and References sections below

  • Invasive Plants - Victorian Resources Online – Department of Economic Development, Jobs, Transport and Resources, Victoria

  • Salinity Indicator Plants - guide to spotting soil salting – Department of Economic Development, Jobs, Transport and Resources, Victoria
  • Greener Pastures for south west Victoria - (2006) Chapter 7Keeping weeds under control. - Department of Primary Industries, Victoria.
  • Miller J. Pasture Doctor.A guide to diagnosing problems in pastures (1995) Press.
  • Weeds Australia. Australian Weeds Committee.
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This project is supported by the Corangamite Catchment Management Authority, through funding from the Australian Government’s Caring for our Country

Page Updated: September 2013
Produced by AS Miner Geotechnical