Farm Ireland
Independent.ie

Monday 25 June 2018

Are your first cut silage yields up to scratch?

Why delaying first cut too long silage past grass heading date will cause a large drop in quality and reduce second cut yields significantly

Delaying first cut silage too long past grass heading date will cause a large drop in quality and reduce second cut yields significantly
Delaying first cut silage too long past grass heading date will cause a large drop in quality and reduce second cut yields significantly

Recent weeks has seen much improved grass growth and ground conditions for most of the country.

Many farms have taken the opportunity to begin harvesting first cut silage. Current weather forecasts are for relatively settled conditions for the week ahead. This should allow more silage area to be harvested in the coming days.

The Teagasc Fodder Working Group is monitoring conditions across various sites nationally. Dr Joe Patton, Teagasc specialist said; “It’s important that the first cut is not delayed and that the majority of farmers plan for a second cut in the 2018 silage season. Every effort should be made to rebuild fodder stocks during the coming months to ensure adequate stocks for the 2018 winter/2019 spring.”

He noted the following trends:

Grass growth

PastureBase data is reporting average daily growth rates of 70 to 80kg Dry Matter per hectare. Differences within county are greater than between counties reflecting individual farm management decisions. Overall, many farms are producing grass surpluses on grazing areas; these will likely need to be removed as baled silage to maintain grass quality.

First cut yields

On areas closed for silage, dry matter yields have increased considerably. Well managed swards in Munster/south Leinster were at 4500 to 5800kg DM per hectare on areas grazed in late March, and 5000 to 6000kg DM on areas closed since autumn.

With these yields in place, quality targets should now dictate cutting date. Delaying first cut too long past grass heading date will cause a large drop in quality and reduce second cut yields significantly. The aim should be to take out main first cut areas by early June; areas grazed twice this spring can be cut around 7-10 days later.   

Grass Sugars

Grass sugars are the main consideration for crop preservation. Indications from various sites around the country are for sugars ranging 1.5 to 3.5pc. 

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The target for good preservation is at least 2.5pc (3pc if wilting is not possible). Older swards with less ryegrass are showing lower sugars. Current conditions are favourable for increased sugars. If in doubt local Teagasc offices will test grass sugars and nitrates to establish best options for cutting.  

Grass Nitrates

Grass nitrates can affect preservation by increasing buffering capacity. However there is good evidence that sugar levels are actually the more important consideration. A grass crop will on average use up 2 units of N per day for first cut, and more during good growing conditions. Nonetheless, this is only a general rule and should not unduly delay cutting date. Local Teagasc offices will test for nitrates in addition to sward sugars.

Wilting

Wilting is very beneficial to silage preservation where sugars are marginal and/or nitrates remain elevated. The aim should be to increase crop Dry Matter to 27-30pc. This is best achieved by tedding out rows and wilting for 24 hours in good conditions.

Data from Teagasc Grange shows that grass left in larger rows (3m+) will not dry sufficiently to be effective. Where surplus bales are made from shorter leafy grass, wilting to 30pc plus will result in better preservation and bales that hold their shape over longer storage periods. There will also be a reduction in baling costs.

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