Low level of reseeding is an issue that must be addressed
Reseeding levels in Ireland are low ranging from 250,000 acres to 320,000 acres annually; in general approximately 2pc of our annual grassland area is reseeded.
As grass is our main feed during the main grazing season, and the primary source of winter forage from grass silage, the low level of reseeding must be addressed.
The increase in the dairy herd size post the abolition of quotas, combined with the focus on efficient beef and sheep meat production means reseeding was never as important as it is now to help keep down high input costs.
The results from Teagasc's national grassland database, PastureBase Ireland, show that there is huge capacity on Irish farms to grow more grass, current annual tonnage is 13.7t DM/ha for dairy farms.
In recent years, on-farm grass variety evaluation has been established, the most recent results show close to a 2t DM/ha difference between varieties with large differences in digestibility and grazing utilisation.
This article is focussed of variety choice for the coming season, given the new format of the Irish Recommended list, variety choice should be based on using the DAFM Recommended list and Pasture Profit Index.
This year, DAFM have published the recommended list, showing the Pasture Profit Index values and agronomic values of the evaluation. See www.agriculture.gov.ie.
The Recommended List has evaluated varieties across years, and sites, and is the only evidence available of the potential performance of grass cultivars in Ireland.
Using varieties not on this list is basically poor decision making, as is buying grass seed on price. The varieties you use on farm will be there for 8-12 years, so choosing to use cheap mixes, with non-recommended varieties will increase the chances of those varieties failing to perform on the farm.
When the decision to reseed is made, the next major decision is selecting the most appropriate grass variety or varieties. The first thing to consider is the primary target use of the field. Is it predominantly grazing or is it generally used as a silage paddock?
How much tetraploid should be used? A balance between quality, dry matter productivity and sward density is generally what must be achieved. The key traits in a seasonal grass based production system are:
- High quality
- High seasonal production
- Good persistency score
Combining diploids and tetraploids in a mixture will create a dense, high quality sward - ensure you select varieties which express high performance in the key traits.
Increasing the proportion of diploids on heavier soils is recommended to create better ground cover, however tetraploids should be used on heavy soils. Choosing all dense varieties will compromise DM production and grazing utilisation.
Joe Kelleher is a Teagasc advisor based in Newcastlewest, Co Limerick
Key points when formulating a grass mixture
- Decide what the end use is - grazing or silage - formulate based on this
- Focus on the key traits increase the proportion of the varieties with the key traits
- Minimum of 3kg of an individual variety
- There should be no more than three to four variety in a grass mix
- Sow 35 kg/ha (14 kg/ac) of seed
- Less than 7 days range in heading date between varieties
Grazing Specific mixtures
- Varieties exhibiting high seasonal (spring and autumn) PPI values
- Varieties with high-quality sub-index values
- Use 40-50pc tetraploid varieties in mixtures on dry soils
- Use 15-20pc of highly persistent tetraploids on heavy soils
- Small/medium leaf white clovers for dairy cows/cattle, small leaf white clovers for sheep
Silage specific mixtures, eg 2-cut system
- Varieties which have high silage sub-index values
- High level of tetraploid (40pc)
- Ensure proximity of heading dates
- Avoid low silage sub-index diploids and poorly persistent tetraploids
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