Hedge Management on Derogation Farms

This year in 2020, for the first time, farmers on Derogation farms, who are availing of the Nitrates Derogation have committed to undertake a Biodiversity Option relating to hedge management. Catherine Keena, Teagasc & Francis Collier, Farm Manager Teagasc Grange look at what the two options involve

(Photo above : Brian Burke) The dunnock or hedge sparrow  perching in a small tree above the body of a hedge.

This year in 2020, for the first time, farmers on Derogation farms, who are availing of the Nitrates Derogation have committed to undertake a Biodiversity Option. This relates to hedge management and farmers must undertake at least one of two options – where hedge cutting is being carried out. There may be some hedges on farms which are not cut and that is acceptable, provided they do not encroach into fields.

The first option

This involves retaining at least one thorn tree in every 300 m of hedge. This can be a whitethorn or blackthorn, either of which are present in practically every farm hedge in Ireland. It can be an existing mature thorn tree although these are rare in topped hedges where, up to now, other tree species (if any) were preferred for retention. Or a new thorn sapling can be retained from within the hedge. It may be easier to leave a bunch in the first year, which can be thinned to a single stem later.

New whitethorn tree retained from within the hedge four years ago in Teagasc Grange.

Whitethorn trees providing flowers for bees and haws for birds

Thorn trees provide many benefits. The flowering May bush is a beautiful landscape feature around first cut silage time. The flowers provide flowers for bees and their haws provide food for birds. Birds such as blackbird, thrush and robin who nest in the body of the hedge need small trees in the hedge to provide a perching post to sing and hold their territory. Birds do not sit on top of a flat topped hedge.

While one thorn tree in 300 m may appear low, it is better to allow another new thorn develop in future years, giving a diversity of height and structure with developing thorn trees at different stages rather than all one height. Option 1 is automatically attained in untopped or escaped hedges or lines of tree which have never been topped and contain numerous thorn trees with a full canopy proving flowers and fruit. Annual side trimming is allowed in Option 1.

The second option

This involves cutting hedges on a three year cycle where it is recommended to cut one third of hedges each year to benefit the environment as much as possible. So where all hedges were cut in 2019, cut one-third in each of 2020, 2021 and 2022.

Best practice for biodiversity on all farms is to have a variety of hedge types. This includes some escaped hedges which remain untopped but can be side - trimmed, and some topped hedges trimmed to a triangular profile from a wide base cutting the growing point except to retain occasional trees including thorns at irregular intervals.

To see all of the activity of Hedgerow Week follow this link  https://www.teagasc.ie/environment/biodiversity--countryside/farmland-habitats/hedgerows/