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Grass margins a simple but effective environmental measure!

Grass margins are strips of untouched vegetation around field boundaries. These margins are typically fenced off and left alone to provide habitat cover and food for flora and fauna to thrive in. Why do we need grass margins? And are they effective? Eanna Loughrey, Teagasc Ballinrobe has answers


The intensification of farming resulted in huge changes in Irish agriculture boosting income on family farms and improving efficiencies on farms, but biodiversity suffered as a result of intensification. To slow the onset of this decline in biodiversity the REPS scheme was rolled out in 1994 and since then there has been a number of similar schemes such as AEOS, GLAS, REAP and in recent weeks the new ACRES scheme has been announced by the Department of Agriculture.

Biodiversity needs to be maintained to avoid losing native species that have struggled with the intensification of farming and face going extinct. The pearl mussel, the barn owl, the corn crake as well as one third of Ireland’s native bees, all face uncertain futures. Leaving grass margins is only one of many methods that can be used to promote biodiversity on farms but it’s becoming more popular as it’s a straight forward measure with relatively low cost involved.

Does it work?  

Grass margins are not a new concept but are gaining in popularity for use across all sectors to improve biodiversity on farms. Tillage farmers were early adaptors of the grass margin especially in countries like England, Scotland and Wales where agri-environmental schemes have been paying farmers to establish grass margins since the 1990’s to the present day.

Grass margins have been shown to improve biodiversity when implemented correctly, but to maximise the environmental benefits of grass margins the condition of the area before the grass margin is implemented must be taken into consideration.

For relatively unimproved pastures that have received low levels of fertiliser simply fencing off the margin and allowing it to mature and flower will provide a good boost to the field’s biodiversity. However, on an intensively farmed pasture, studies have shown that very little benefit was derived from minimal change management and that sowing of wildflower seed mixtures was needed to re-establish plant diversity in the field margin. It should be noted that only certified native Irish wildflower seed mixes should be used and generic wildflower seed mixes should be avoided as they may introduce invasive species into the field.


Management of the accumulated vegetation at the end of the year is needed to prevent encroachment from hedges and give a better chance to the wild flowers to establish in the following year. Vegetation should be grazed, topped, or mown anytime from the middle of September to the end of February. Fertilizer accidently ending up in a grass margin will impede the establishment of wildflowers so be extra vigilant when spreading fertiliser.

Margin width

Opting for a wider grass margin has obvious environmental benefits but has also been shown to reduce the abundance of noxious weeds in the margin. From a practical point of view wider margins also means less fencing is needed for the same area of grass margin and allows more options for the control of vegetation

Grass margins will be a measure in the soon to open ACRES agri-environmental scheme so it would be a good exercise to reflect on your own farms suitability to incorporate grass margins.

You might also find the article Managing Margins with Nature in Mind of interest.

If you have any questions around biodiversity or grass margins contact your local Teagasc advisor at your local Teagasc Advisory Office here: Advisory Regions. Teagasc Advisors are regular contributors of articles on Teagasc Daily