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Visual indicators of soil condition

Item 17 of 17
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Low fertility indicators

What weeds do you see and when?

  • High content of bent grass, fog grass, silver grass, onion grass, flatweed, sweet vernal grass and/or sorrel within pasture.
  • Seen from autumn to December.
Bent grass (Agrostis spp)
Fog grass (Holcus lanatus)
Flatweed (Hypochaeris radicata)
Sweet vernal grass (Anthoxanthum odoratum)
Silver grass (Vulpia bromoides)
Onion grass (Romulea rosea)
Sorrel (Rumex vulgaris)

What could this indicate?

  • Low fertility. Bent grass and fog grass are general indicators of low fertility, especially nitrogen and also phosphorus, potassium, sulphur and soil acidity.
  • Low nitrogen. Silver grass
  • Low phosphorus. Onion grass
  • Low potassium. Flatweed, sorrel and sweet vernal grass Common on light textured soils (as potassium leaches) and on paddocks repeatedly cut for hay or silage.
  • Soil acidity. Sorrel
  • Also favours silver grass, bent grass and fog
    grass growth as nitrogen fixation of legumes
    declines.

What test can I do to confirm?

  • Soil test with reference to nitrogen, phosphorus, potassium and soil pH.
Pictured: Sorrel becomes obvious during spring due to red seed heads.

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