Three-leaf theory

Thursday, 4 March 2021

With a challenging start to the grazing season, it’s worth remembering three-leaf theory when faced with any difficult decisions, or grazing disasters, this year.

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Understanding how the rye-grass plant grows helps with important management issues, such as residual height and post-grazing recovery time.

  • A rye-grass plant only ever grows three live leaves: when a fourth leaf appears, the first leaf dies off
  • Leaf 1 produces 10–15% of the grass in a sward
  • Leaf 2 produces 30–40% of the grass
  • Leaf 3 produces 45–55% of the grass
  • Best-quality grass is between 2.5 and 3 leaves
  • Lengthening grazing round to 23–24 days grows an extra 0.5 of a leaf
  • Graze at 8–10 cm, leave a residual of 4–5 cm – sugars are stored in this stubble and help to grow the next leaf after grazing
  • Leave 4–5 cm between clumps and 10 cm on clumps to achieve a balance between residual
  • Leaf appearance rate depends on temperature and moisture

For more information, check out AHDB’s Grass+ factsheet 15 and AHDB Planning grazing strategies