Sheep, cattle and suckler farmers could see higher margins from selling three well-yielding cuts of red clover silage to anaerobic digestion (AD) than they would from keeping the same land under their existing enterprise, according to figures from the rural economy wing in Teagasc.

Research officer Dr Ciara Beausang stated that the same would not necessarily be true in the case of the average tillage or dairy farm.

Beausang gave an overview of the authority’s number crunching on grass-clover silage as an AD feedstock at an Irish Bioenergy Association farm biogas conference on Thursday.

Teagasc's study assumed that three cuts could be taken each year to give an overall yield of 14t DM/ha, with no costs associated with land or capital expenditure, such as silage pits, included in the calculations.

It was also assumed that some of the digestate would be recycled back to farm, but that nutrient levels would need to be topped up with chemical phosphorus and potassium.

Economics

“What they wanted to do was look at if a farmer decided to grow grass silage, what impact would it have on the economics of their farm compared to the existing farm enterprise,” the conference heard from the research officer.

“They modelled the price of the silage [at] three different price points - €30/t, €40/t and €50t.

“Firstly, you can see that if you are in a dairy enterprise, it is not profitable for you to grow grass silage as an AD feedstock compared to your current farming system.

“Similarly for tillage, it depends on the price you get for silage. Potentially at a higher price for silage, it may be more profitable and indeed growing grass silage in a tillage system may be more profitable than the least profitable crop in the tillage rotation.

“If you look at the other systems - cattle and sheep farms - potentially growing grass silage may be more profitable on a per-hectare basis than the existing farm systems.”

Figures presented by Beausang showed that the modelling of red clover silage left dairy the more profitable option by around €500/ha at a silage price of €40/t, while feedstock silage replacing tillage would leave a slightly higher margin at €35/t, rising to a €200/ha gain at €40/t.

A €35/t red clover silage feedstock was estimated to add approximately €200/ha on top of what cattle, sheep and suckler farms were expected to return from their regular enterprise, jumping to about €500/ha if a price of €40/t was received.