Quality Meat Scotland (QMS) has announced that digestate and compost products produced from anaerobic digestion (AD) is safe for cattle farmers to use on their agricultural land.

The AD process involves breaking down biodegradable material (such as household food waste and farmyard manures) using microorganisms in the absence of oxygen to produce gas for energy. The process also creates a digestate, a nutrient-rich substance that can be used as a fertiliser.

Concerns had previously been raised that AD could actively cultivate the Clostridium botulinum organism, which can cause paralysis in both humans and animals.

However, QMS has said that three separate research projects recently found that there was ‘no significant growth’ of the organism in AD, and that risks were similarly low to those associated with livestock slurries.

As such, it has updated its Bulk Organic Fertilisers section of its Cattle & Sheep Standards to allow composts and digestates to be applied to land, provided they are PAS 100 and PAS 110 certified, and meet the criteria in the guidance.

However, the standards state that ‘no graze’ and ‘no harvest’ intervals should be observed to ‘ensure the benefit of these materials is realised’, and that these intervals are statutory when involving compost/digestate produced from animal by-products, such as household food waste.

This could be relevant to many farmers sourcing digestate from AD, as it is now compulsory for local authorities and large food businesses to collect food waste for recycling (such as through AD).

‘A breakthrough for a circular economy in Scotland’

Zero Waste Scotland has welcomed the announcement, with Iain Gulland, Chief Executive, claiming that the decision was a “breakthrough for a circular economy in Scotland”.

He stated: “Food and other organic wastes contain nutrients which are important to plant growth, so it’s appropriate they are returned to the soil when it’s safe and right to do so.

“Zero Waste Scotland has worked extensively with the organics recycling sector over several years to develop a robust body of evidence on outputs from compost or anaerobic digestion (AD) facilities. It’s now clear that these products, when made to a quality specification, do not pose a risk to human or animal health.

“This will help us advance towards our goal of diverting food waste from landfill, on which a great deal of progress has already been made, and will help farmers reduce their reliance on oil-based fertilisers.”

Gulland added that the decision will help “open up a potential new market for these products”, but that it is vital for the food waste supply chain to help the organics recycling “deliver consistent, high-quality materials to farmers who want to use them”.

“If they do, this is a clear win-win, for farming and for zero waste”, he added.

Find out more about the QMS Cattle & Sheep Standards.