Do you know what grass varieties you will sow this autumn?
Reseeding can often be a daunting task for many farmers as there are a lot of things that need to be taken into consideration; choosing which grass varieties to sow being one of them.
However, during a reseeding event held by Germinal Ireland, Mary McEvoy – a technical development manager with Germinal – outlined some of the key things that farmers need to take into consideration when picking the most suitable grass varieties for a new reseed.
The first place to start, according to Mary, is to “look at the Pasture Profit Index (PPI) or the recommended list”.
“The PPI is like an EBI for grass varieties. It quantifies the key traits from a grass production perspective,” explained Mary.
In terms of the persistency value, Mary explained: “Zero is indicating a variety that is lasting 12 years or more.
“Although some varieties have a persistency of minus five and others have a persistency of minus 11; if it is minus five, it is indicating that it is lasting 11 years, and if it minus 11 it is lasting 10 years.”
However, Mary noted that the real driver of persistency in a grass sward is soil fertility.
Furthermore, Mary pointed out that the quality sub-index is hugely important when it comes to grazing mixes.
“The difference between the highest quality variety and the lowest quality variety on the PPI is €94/ha/year.
Explaining the reason for this, Mary said: “With a higher quality variety the animal will eat more, which is going to have a positive effect on animal production.
“The reverse of that is lower-quality varieties have more fibre going into the rumen – so they fill the cow up quicker – and she will be eating less of a lower quality feed. This will have a knock-on effect on the performance of the cow.
“So, it is important that your mixes contain varieties that are performing very well on the quality sub-index,” she added.
Tetraploid vs. diploid
In relation to the percentage of tetraploid versus diploid varieties in a mix, Mary said: “My advice is to have a 50:50 mix of tetraploid versus diploid – under good soil conditions or where the ground can take that amount of tetraploid.
“In the case of tetraploid in the sward, animals will graze them out and utilise them better which means that they can consume more of them.
“Diploid, on the other hand, brings the density to the sward – attacking like a carpet and minimising the risk of poaching. Consequently, for heavier soils the proportion of diploid in the mix can be increased for greater ground cover.
“If you had a pure tetraploid sward it would be quite open and much more susceptible to poaching damage.”
Mary also made reference to the heading date of the varieties. This is when the variety turns reproductive and when this happens the quality declines.
Advising farmers, she said: “If you have a narrow range in heading date it is much easier to pinpoint the optimum time to go in and graze that sward – to get it back to its vegetative state.
Also, with a silage mixture, once the sward turns reproductive you start to loose 3% to 4% of dry matter digestibility [DMD] on a weekly basis.
“Again, a narrow range allows you to get in before it turns reproductive.”
Going forward, the inclusion of clover in our mixtures is going to become more and more important.
Touching finally on clover, she said: “There is huge value in including clover in your mixes, but there are some management issues to bear in mind.Also Read: Grass-clover sward has the potential to deliver ‘€305/ha extra net profit per year’
“If you haven’t included it on your farm up until now, don’t go mad including 1.5kg when you are reseeding; start at 0.5kg or maybe 1kg; but don’t go any higher.
“Build it gradually across the farm, so you’re not going from a field with no clover to a huge amount of clover on the farm.”