The merits of mixes versus single varieties
More than 95pc of the grass-seed sold to Irish farmers is in the form of a mix, but recent research by Teagasc shows that no mix was able to out-perform the top ranking variety.
This suggests that farmers should insist on only the best varieties being included in any mix, since its subsequent performance will be dependent on the sum of its parts.
"This is a new era in grass-seed formulation, where grass varieties need to be be fit for purpose and outclassed varieties will be shown up for what they are," commented Michael O'Donovan.
But why opt for a mix at all if they can't out-perform the top ranked varieity in any particular trait?
"No single variety has all the traits, whether its heading date, digestibility, persistence or yield, so it still makes sense for farmers to cover all the bases with a mix, provided that there are no 'filler' varieties in the mix," said the researcher.
"The most important aspect in mixture composition is to use varieties from the recommended list, and ensure that the varieties chosen has the traits required in a sward on the farm," he said.
However, mixes pose a particular set of challenges for scientists like Dr O'Donovan because the relative proportions of different varieties can change significantly over the course of a few years, especially in the case of mixtures with tetraploids.
In trials using varying proportions of the diploid Abermagic and the tetraploid Greengold, the latter variety tended to colonise at least half of the area, even when it was initially included at rates as low as 15pc of the total mix.