Northern Ireland

What is bog butter and why are Irish farmers finding it thousands of years later?

The practice of storing butter in bogs dates as far back as the Bronze Age

The preserved slab of butter was found on a farm in Portnoo, Co Donegal in July
A 22kg slab of bog butter was discovered in Portnoo, Co Donegal in July
By Mark Robinson

A Co Donegal farmer recently became one of the latest people to discover ‘bog butter’ on his land.

The substance, which is often white-yellowish in colour and waxy in texture, has been found in bogs all over Ireland.

But what exactly is it?

More: Donegal farmer uncovers 22kg slab of ancient bog butter

Is it real butter?

Yes – bog butter is typically made from milk fat, especially those found in Ireland.

Studies conducted by the National Museum of Ireland have found that bog butter in Ireland is “almost always” real butter.

While it may be real butter, the jury is out on whether or not it’s ‘edible’ – some say it still tastes fine, while others have described it as “putrid”.

It is typically found with the container in which it was stored – these can range from bowls to wooden kegs.

They have also been found wrapped in animal hide and, in some instances, consist of animal fat, like lard, rather than dairy.

How old is it?

Studies indicate that the usage of bogs to preserve dairy products is a millennia-old practice.

Bog butter with the wooden keg it was discovered in (University College Dublin)
Bog butter dating back more than 2,300 years with the wooden keg it was discovered in (National Museum of Ireland)

Bog butter samples found in Ireland have been dated as far back as 1,700 BC, while more recent discoveries date back to the 16th and 17th centuries.

Why is it found today?

While opinions on the reason behind storing butter in bogs differ, from using the bog to hide resources to leaving gifts for the gods, most would argue that it was for preservation – a bit like a pre-historic fridge.

Bogs have fridge-like qualities in that they are ideal for preserving food in their cool, low-oxygen, high-acid environment.

These same qualities allow for long-lasting preservation, meaning that the bog butter has remained intact for hundreds or even thousands of years after being first placed there.

Modern farmers have often stumbled across the substance when extracting peat, draining bogs or carrying out other excavation work.