A numbers game
New pastures of mixed species are typically sown with 8–12kg/ha of perennial ryegrass seed or 3–4kg/ ha of cocksfoot seed. Estimated seed yields for thinning ryegrass or cocksfoot within mixed pasture could be 130kg/ha and 50kg/ha for cocksfoot. This equates to approximately 7,000 seeds/m2 for ryegrass and 9,500 seeds/m2 for cocksfoot.*
* Results based on crop seed production of 1.3t/ha perennial ryegrass and 0.5t/ha cocksfoot. In a mixed poor perennial pasture, it is estimated that seed yields could be approximately 10%. One kilogram of perennial ryegrass seed equals 320 seeds/m2 and one kilogram of cocksfoot is 760 seeds/m2.
Where does all this seed go?
In a grazed pasture most is ingested by animals, which makes the seed unviable. If not removed by grazing, the main source of loss is ant predation. However, even achieving a 3% success rate with the high amounts of available seed equates to 200–300 seedlings/m2.