A farmer taking part in trials to see how the plant matter which is left after crops have been through an anaerobic digestion (AD) process – combined with a cover crop – can help soils and yields says he feels “very encouraged” by the results so far.
Andrew Blenkiron, director of the Euston Estate, near Thetford, is one of six farmers to have taken part in Agri-Tech East's Innovative Farmers Field Lab digestate project, with the research led by NIAB and Cranfield University.
As well as producing biogas which can be fed onto the gas grid as it is at Euston, AD plants produce a highly nutritious by-product - called digestate - but not much is known about the best way to use it.
What farmers and researchers wanted to know was whether cover crops could be used to stabilise the nutrients, including nitrogen, which it provides and improve its use as an alternative to chemical fertilisers on crops.
Now the initial findings of the field lab projects are set to be discussed at an open Agri-Tech East event at Cambridge on September 12, as estimates suggest it could save £110 a hectare on artificial fertiliser application.
While it's too early to tell definitively, Andrew believes soil health has improved considerably as a result of the digestate application and cover crop regime, and his fertiliser costs have come down. Since the AD plant was installed, the digestate has already proved a valuable source of nitrogen, bringing down his fertiliser costs by £80k a year, he adds.
Andrew found that on his light, free-draining soil, maize yields grown afterwards did take a hit last year, but he believes that was a blip caused by the unprecedented two-month heatwave.
"It's actually showing some quite positive results across the whole of the region," he says. "One of the big challenges we faces is a field is not a science lab - there are all sorts of variables creeping in."
He adds: "By the end of September next year we'll have three years of trials which I think will demonstrate some very positive results."
NIAB's Lydia Smith says the field lab was set up to answer a number of questions. "In particular the farmers were interested in the use of cover crops to stabilise the nutrients present in the digestate, so that crops benefit."
Ruminating on the role of digestate in managing healthy soils is at NIAB Park Farm, Cambridge CB24 9NZ on Thursday, September 12, from 3pm to 7.30pm. Farmers and others with an interest in digestate are welcome to attend.
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