AD digestate ‘safe’ for farmers crops in Scotland

Anaerobic digestion (AD) involves breaking down biodegradable material such as household food waste, and farmyard manures, using micro-organisms in the absence of oxygen.

The process provides a source of renewable energy and also produces a rich bio-fertiliser, which is high in valuable nutrients such as nitrogen, phosphorus and other elements required for healthy plant growth and fertile soil. This can then be used back on farmland to grow more food and keep the soil healthy.

Given that there are 1.3 million homes in Scotland with a food waste collection, this announcement could mean less waste sent to landfill and cheaper fertiliser for Scottish farmers, who have until now been warned off from using digestate to grow animal feed crops.

Closing the loop

The move was welcomed by Zero Waste Scotland, whose executive Iain Gulland said: “This decision is a breakthrough for a circular economy in Scotland.

“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.”

Gulland added that Zero Waste Scotland had tested digestate for several years and that it was clearly not a risk to humans or animals.

“This will help us advance towards our goal of diverting food waste from landfill and will help farmers reduce their reliance on oil-based fertilisers,” he said.

“This decision opens up a potential new market for these products, but it is vital that the whole food waste supply chain responds by enabling the organics recycling industry to 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.”

Earlier this year a UK regulation change allowed digestate to be labelled and sold as ‘biofertiliser’, reflecting its benefits for crops and the environment.

VIDEO: Using digestate as biofertiliser (source: WRAP)

Brad Allen