New Maize Types Can Increase Biogas Yields By 10-15%

That’s the view of Europe’s leading maize breeder, KWS, the only company to have a dedicated long-term breeding and selection programme for biogas use.

According to KWS UK maize specialist, John Burgess, over 90% of all biogas installations in Germany use maize as a principle substrate to fuel plants.

And, while other crop use is increasing – most notably sugar beet – the sheer physical bio-mass that can be produced makes maize an ideal crop to provide the bulk needed.

“Our breeding team has been working with gigantic maize types originally from S America since 2002,” he says.

“They have now adapted these types such that they can give secure, stable yields from varieties that have the cold tolerance, maturity and standing ability to cope with UK conditions.”

Trials with our commercial partners– as far north as Angus – confirm that they can significantly out-yield types originally bred for use as forage crops for livestock, suggests Mr Burgess.

What we are aiming for is the right balance of starch from the grain and cellulose from the stover.  Maize bred for digestion by ruminants often has too high a cob to plant ratio, he points out.

However, by redressing this balance of whole plant sugars to humicellulose and cellulose within biogas maize varieties – plant operators can get a longer, more efficient biodigestion.

Mr Burgess points out that maize bred to be fed to cattle needs to provide minimum methane production in the rumen and give maximum feed value by way of starch and digestibility.

This is exactly the opposite of what is required in biogas production.  Here, you want maximum methane productivity from a crop that can have a dwell time in the plant of 50-100 days rather than the 5-10 hours in the cow.

In addition, when selecting maize for cattle, you need dry matters of between 30-35% for good feed intake; for biogas, lower levels of 27-31% are better for the fermentation process. 

“Anything over 35% can compromise the bacterial activity needed to power methane production in the biogas plant,” he says.

Not surprisingly, it makes no sense to use inappropriate material, and biogas operators need to ensure they have tried and tested purpose-designed energy maize types.  

“In this respect, buying in any old forage maize from livestock farms is not the answer, far better to contract grow energy maize types going all out for yield.”

Mr Burgess suggests that those who are best placed to grow energy maize types could well be arable crop producers.

“At the very least, energy maize growers need to grow for yield and this involves maximising input use to boost plant growth and ensuring minimal weed competition.

Many cereal farmers looking for an alternative break crop could find that energy maize is an ideal fit,” he suggests.

Whereas forage maize is normally grown on lighter land, biogas maize will do equally well on heavier land.  Indeed on more productive ground crops will give higher yields.

And with many cereal producers struggling to get on top of blackgrass, energy maize gives you a full seven month window at least to get on top of the weed prior to spring planting.

Mr Burgess points out that fears over mycotoxins from maize in the rotation should be minimal.  “Whereas grain maize and some later forage types could increase the risk of fusarium in the following cereal, this is unlikely to be an issue with energy types.

“They are earlier to harvest and growers will take as much of the crop as they can, thereby minimising the risk of recycling from maize stubbles to the following cereal.”

“We know of an increasing number of growers who have struggled to maintain beet quotas who are turning to energy maize.  It’s an ideal alternative, utilising the same cultivation and drilling kit already in the farm machinery store,” says John.

“However, maize does well across areas where beet is not an option, so there is no reason why most livestock or arable farmers shouldn’t embrace the crop.”

KWS UK has been examining the potential of a range of early – mid-early and late hybrids – for energy maize across the UK. 

Later types such as Francisco can deliver the highest yields, but earlier types such as Kadenz will be more suited to sites where earlier maturity is required.

“Realistically, biogas producers will be better selecting a range of types which will help spread the harvest and drilling workloads, and yet still ensure the highest yields in the clamp and in terms of methane production.

“Those who don’t want to do the job themselves will find that there is a new breed of farm contractors – often working across arable crop rotations – who will help meet the burgeoning need for maize near to biogas plants,” he points out.