How High To Cut For Silage?

Many producers are talking about going for bulk with their first cuts this year to replenish, as much as possible, empty silos etc.  A common thought would be to –

• Delay cutting by 1 or 2 weeks and
• Mow as close to the ground as possible.

Mowing as close to the ground as possible will produce a higher yield of dry matter per hectare but this will be greatly outweighed by –

• An increase risk of machinery damage.
• Swards may be scalped due to ground irregularities and produce very little growth for the rest of the year.
• A short stubble will hinder wilting due to poor air circulation through the swath.
• Herbage quality will be decreased due to a higher proportion of stem and dead material, with little or no feed value, being harvested.
• Greater soil contamination resulting in poorer silage fermentation, lower intakes and a higher risk of Listeriosis.
• A slower regrowth due to few if any green leaves in the immediate aftermath. This will be particularly critical in hot dry conditions.

When grass supplies are short it is perhaps even more critical to cut at the recommended level of 3 – 4 cm for perennial ryegrass and 5 – 6 cm for Italian or hybrid ryegrass swards.

David Lawson, david.lawson@sruc.ac.uk