Growing grain for the glass

Irish barley is the backbone of Ireland’s brewing and distilling industry. But could Irish-grown wheat,
maize and rye reduce reliance on imports? A Teagasc study explores the possibilities.

Photo credit: Teagasc.

Significant amounts of Irish-grown grain are used in the brewing and distilling sector in Ireland and it is an important premium-value market for growers. Barley has been, and continues to be, the grain most associated with the sector; in fact, the majority of Irish-grown grain used by the sector is barley, produced to a range of different quality specifications depending on the requirements of the end-user.

Richie Hackett, Research Officer at Teagasc Oak Park’s Crop Research Centre, says: “Over the years, extensive research has focused on optimising barley production to meet these specifications. Except for seasons marked by very poor weather, the Irish industry has largely met its own demand for malting barley.”

Exploring alternatives to barley

While barley remains dominant, other grains such as maize, wheat, and rye are used to varying extents, and some are currently imported. The Department of Agriculture, Food and the Marine-funded project ‘Distilling and Brewing – Building Capacity’ explored how more of these grains could be sourced from Irish farms.

“One key question was whether Irish-grown winter wheat could substitute for the large quantities of imported maize used in grain whiskey production,” Richie explains.

“The project also investigated the potential to grow grain maize domestically, and explored the agronomy – the application of science and technology to the improvement of major food crops – of hybrid rye, a newer crop for Irish farms.”

Investigating winter wheat for distilling

Winter wheat is already used in countries such as Scotland, and by some Irish distilleries, as a substitute for maize in grain whiskey production. However, replacing maize with wheat can cause processing issues such as excessive foaming and sticky, viscous residues that are difficult to remove from distillation equipment.

“These challenges are especially problematic in Irish distilleries due to the unique processes used in domestic grain whiskey production,” explains Richie.

Wheat also tends to yield less alcohol per tonne of grain than maize, which affects profitability. International research suggests that both the wheat cultivar (a plant variety bred for traits like yield or disease resistance) and management practices, particularly nitrogen fertiliser application, can influence its suitability for distillation.

Wheats with a soft endosperm texture break down more easily during processing and are preferred by distilleries. However, most winter wheat cultivars currently grown in Ireland have a hard endosperm texture, making them less ideal for this purpose.

To assess alternatives, the study compared several soft wheat cultivars, including those used in Scotland, with commonly grown Irish hard wheat varieties. Trials were conducted at two Irish locations over three growing seasons. Results showed that soft wheat cultivars could achieve comparable yields and similar grain quality to varieties on the Irish recommended list.

Unfortunately, many of these promising cultivars proved vulnerable to Septoria leaf blotch, a widespread and damaging fungal disease in Ireland. The pathogen had evolved to overcome a key resistance gene, making these cultivars too risky to grow at scale.

Encouragingly, new soft wheat varieties with improved disease resistance and strong distillation traits are under development and are expected to become available to Irish growers in the near future.

Maize potential under Irish conditions

Irish-grown wheat may help reduce reliance on imported maize. Photo credit: Teagasc.

While much of the research focused on using wheat to replace imported maize, the research also examined whether grain maize could be grown in Ireland to serve the same purpose.

Maize is widely cultivated for forage (animal feed) in Ireland, where the entire plant is harvested and ensiled (fermented and stored). However, harvesting maize for grain is uncommon, as most forage varieties do not produce grain with low enough moisture content for safe storage without drying.

Researchers trialled early- and very-early-maturing maize varieties, with and without biodegradable mulch (a soil covering that speeds up plant development). The results were promising: when sown early and grown with mulch, the maize produced grain yields comparable to other cereals.

However, the harvested grain consistently had moisture levels too high for safe storage, meaning that costly drying would be required. This challenge was worsened by the fact that most of the ‘dry-down’ period, when the crop loses moisture naturally, occurred in October, a month often marked by poor drying conditions.

“Encouragingly, the very early varieties dried down earlier, reaching maturity in September, when drying conditions are typically more favourable,” adds Richie. “This suggests that, with further breeding, maize varieties better suited to Irish conditions could be developed.”

Additionally, projected increases in temperature due to climate change may improve the viability of grain maize production in Ireland in the coming decades.

Rye’s promise for whiskey

Rye exhibits good agronomic traits and can be used in the distilling sector. Photo credit: Teagasc.

Another new crop, the production of which was examined under Irish conditions as part of the project, was rye. Rye grain can be used to produce rye whiskey with a number of examples currently being produced by Irish distilleries.

A significant amount of research was carried out to develop suitable agronomy guidelines for the production of rye.

Although the market for rye in Ireland is currently limited and it has some drawbacks, notably being very susceptible to slug damage in the establishment phase, it was found to possess a number of traits that made it suitable for production in Ireland.

“Beneficial traits of rye included high yield, good fungal disease resistance, good tolerance of the aphid borne virus BYDV – which can cause considerable yield loss in other cereal crops – and good fertiliser nitrogen use efficiency,” Richie notes. “It was also shown to have a low carbon footprint, which is becoming an important trait for many end users.”

Overall, the research suggested that, with the right applied agronomy, both hybrid rye and wheat hold potential as additional grain options for the brewing and distilling sector.

Acknowledgments

This work was carried out as part of the project ‘Distilling and Brewing – Building Capacity’ (DABBING CAP), funded by the Department of Agriculture, Food and the Marine (grant number 2019R563).

CONTRIBUTOR

Richie Hackett, Research Officer, Crops Research Centre, Teagasc Oak Park.

richie.hackett[at]teagasc.ie