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Catherina Cunnane
Catherina Cunnane
Catherina Cunnane hails from a sixth-generation drystock and specialised pedigree suckler enterprise in Co. Mayo. She currently holds the positions of editor and general manager at That's Farming, having joined the firm during its start-up phase in 2015.
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Start planning first-cut silage now

I am sure you think first-cut silage is a long way away, but preparation now is essential for best results, writes Michael Verner, CAFRE dairying adviser.

Poor-quality silage often results in poor animal performance. It can also have serious economic effects during the winter feeding period with additional concentrates needing to be fed.

Weather and contractors often get the blame for poor quality silage, but there are other reasons! Decisions and actions, you take now can help you make high-quality first-cut silage this year.

As with all nutrient planning, an up-to-date soil test is vital to allow the most cost-effective use of both fertilisers and manures.

An up-to-date soil analysis indicates if lime is required as well as checking Phosphorous (P) and Potash (K) levels. Aim to test 25% of the farm every year, meaning the whole farm is sampled every four years.

You should assess swards for dead grassy material. Hopefully, you have been able to graze silage swards in late autumn, or perhaps early spring, to avoid dead material in the crop as this will greatly improve silage quality.

Spreading slurry

Slurry should be applied, taking into account NAP guidelines. Slurry should only be spread on low grass covers and should be applied at least six weeks before silage making to avoid contamination, leading to fermentation problems.

Ground, which has been trampled by stock or damaged by machinery, may need to be rolled to avoid soil being brought in with harvested grass, causing contamination and high ash levels in first-cut silage. This is especially important on the ground, which will be tedded and raked.


Timely application of nitrogen (N) fertiliser will help stimulate grass growth. This will be most effective on swards with a high proportion of perennial ryegrass. Too much N produces grass with low sugar levels, and any resulting silage can have high ammonia and butyric acid levels, making it less palatable.

Too little N compromises yield and protein levels can be low. Once the soil has reached 5.5 degrees at 10cm depth for 3-4 consecutive days, grassland can utilise 2.5 kg N/ha/day (around 2 units of N/acre/day) under ideal weather conditions. Your application rate and date need to fit with your planned harvest date.

Typically, apply total nitrogen (N) at from 100 to 120 kg/ha from the combined input of inorganic fertiliser and slurry. (Allow approximately 7 kg N per 4,500 litres (1,000 gallons) undiluted cattle slurry).

For Phosphate (P) and Potash (K) recommendations, the results of a recent soil analysis showing the soil index is needed.

If you employ a contractor or even if you’re using your own equipment, everyone needs to be primed and ready for your planned cutting date.

On many farms, cutting date has been a compromise between yield and quality, with the aim of less than 50% ear emergence of the sward. However, by cutting earlier, there is a significant increase in nutritional quality. A slight yield penalty will offset this.

Act now

In summary, grass silage is the most important component of the diet for at least six months of the year on most dairy farms in Northern Ireland.

Decisions taken now and over the next number of weeks will have a major effect on first-cut silage quality next winter.

A delay in harvesting of one week from mid-May onwards typically results in a reduction in D-value of up to 3 units. This can result in a reduction in milk yield of 1.0 -1.2 litres/day.

Read more articles from CAFRE.

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