Projected growth in biomethane production from anaerobic digestion has the potential to support a strong future for UK hybrid rye. CPM finds out why confidence is strong, and whether this could power opportunity into reality.
“On a tonnage-in basis, rye is higher yielding in terms of gas production than either 1t of food waste or livestock manure.” LUCY HOPWOOD
By Rob Jones and Janine Adamson
The UK’s energy policy landscape is evolving and should offer strong growth opportunities for the anaerobic digestion industry, believes Alder BioInsights’ Lucy Hopwood. She highlights that since its launch in 2021, the current Green Gas Support Scheme (GGSS) has stimulated further growth in AD and will continue to do so until 2028.
“As UK farming continues to adopt more sustainable farming practices, an increase in AD capacity can further support decarbonisation of our energy system, while at the same time, deliver emission reductions for the industry.
“During the past five years under the GGSS, 12 new biomethane projects have been commissioned, with a further 22 in development and set to become operational by 2028. All have planning, grid capacity and finance already in place. Importantly for both UK maize and rye growers, all these new plants will require a secure supply of feedstock, so its highly likely we’ll see greater demand for both crops to meet future supply levels.”
Lucy says alongside maize, rye has established itself as one of the most reliable feedstocks for supply into AD in recent years. This is because while the quality of inputs such as food waste can vary, a consistent, stable supply of high quality feedstock is fundamentally important to successful AD production from both a biological and commercial productivity perspective, she adds.
STRONG AND STABLE
“On a tonnage-in basis, rye is higher yielding in terms of gas production than either 1t of food waste or livestock manure, providing a strong and stable output. Rye also has key advantages over other crops in its drilling flexibility and drought tolerance.
“During the past three years, the UK has experienced two exceptionally dry seasons, so this last trait could prove especially important if these extreme weather patterns are to become the new normal.”
Considering Alder BioInsights’ latest analysis on sustainable feedstocks, a tenfold increase in biomethane production could be achieved by 2050, raises Lucy, making a critical contribution to decarbonisation efforts in energy and agriculture.
With wholecrop for biogas production still the biggest single market for hybrid rye, independent agronomist Craig Green of CMG Agronomy also sees a bright future for the crop, particularly given the consistent expansion of the AD sector. “Of the 58,000ha of rye grown last year, more than 50% of the area was wholecrop for AD. Although it’s not a true break crop, hybrid rye offers a very low input-high output option.
“It has exceptional drought tolerance, can be grown on poor quality land that won’t support wheat or barley, and its low susceptibility to take-all makes it a stronger option than a second wheat.
“Furthermore, combining rye or growing wholecrop rye for AD effectively gives farmers two different break crop opportunities. If they go down the AD route, it can be harvested early in June or July, offering an excellent entry for oilseed rape. While if growers choose to combine rye, the crop is harvested later with the benefits of producing up to 1.5 times more straw than either wheat or barley,” states Craig.
He also highlights that in regard to fertiliser inputs, a standard rye crop may realistically receive around 120kgN/ha – an average 50% reduction compared with what’s typically applied to winter wheat. “Rye is simply one of the lowest input crops and will fit into almost any rotation,” he proposes.
Considering the rye varieties currently available, Craig points out that Saaten Union has seven of the 11 options on the current Descriptive List (DL). “So it’s fair to say they’ve tended to dominate the rye sector since the arrival of SU Performer many years ago.
STANDING OUT
“Having independently trialled most of the current listed varieties, SU Thor – a dual purpose high yielding rye – has been the stand-out for me during the past three years. Particularly last year, during one of the longest droughts on record, Thor remained green well into July for many of my farmer customers, and with a treated yield of 108% in the East, it has very few weaknesses.”
Of the more recent entrants onto the DL, SU Karlsson and SU Erling have both caught Craig’s eye. Having followed these two varieties in trials, he says both look agronomically robust, with Erling’s very stiff straw giving it an advantage over Thor.
“Erling is early maturing, reminding me of former variety SU Nasri in that respect. Given its earlier to harvest it’s also incredibly N-efficient, outperforming all the other rye varieties I saw in trials last year by around 20kgN/ha,” he adds.
Also monitoring the performance of rye variety trials is Philip Marr, renewable biomass consultant for Agrii. Having trialled 146 varieties during the past 15 years, he stresses that focus shouldn’t just be on yield – with speed of leaf development, overall disease resistance and response to varying rates of nitrogen all essential to the evaluation of each contender.
“We look at every variety during a three-year period – it’s a very thorough and transparent process with the specific aim of finding out as much as we can about each rye variety. At the end of each trial, we send tissue samples to the renewable research department at Sheffield University where biomass is measured and converted into biogas yields in m3/t.
“Since our research began, we’ve been able to successfully identify a significant difference in gas output levels between individual varieties. Often these differences can be as large as 60-70m3 of biogas per tonne of freshweight material.”
Philip points out that although 60-70m3 may not sound much, with clamps of farm-fed AD plants often holding tens of thousands of tonnes, the overall gas output between varieties can be measured in seven digit figures, so millions of m3 of biogas. “Variety choice definitely matters – especially with yield differences of 20-25t/ha between the best and worst performing rye varieties.
“Based on the past two years of results, Erling and Karlsson have topped Agrii trials in terms of both freshweight and biogas yields. Although both have also recorded very high grain yields, I see both Erling and Karlsson as true biomass types offering strong traits for growers seeking higher gas yields for supply into AD plants.”
VARIETY CHOICE
Kurtis Scarboro, crop manager for cereals and oilseeds at Elsoms Seeds – the breeder that markets all Saaten Union varieties in the UK – agrees that identifying high gas-yielding varieties is critical as the AD sector continues to develop in importance.
“As the only new addition on the 2026/27 winter rye DL, Erling offers a grain yield of 103% of controls; it’s a high-yielding, high output, true dual purpose variety suitable for both the grain and AD markets.
“With a short, stiff stem its relatively straight forward to manage with low susceptibility to lodging, and has the built-in guarantees of high straw yields from its tillering capacity. This is supported by good overall disease resistance and a moderately fast growth development through the spring, a characteristic that rye growers particularly like,” he concludes.
This article was taken from the latest issue of CPM. Read the article in full here.
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