Reducing carbon through the crop growing cycle is a minefield for UK arable producers, with the only certainty being that it is a goal which will increasingly lie at the heart of many business decisions in the future.
That is the view of Dr Kirsty Richards, of KWS UK, who says: “We are all wrestling with exactly what the implications of reducing carbon are for UK growers and while much of the debate hinges around the obvious need to reduce inputs and manage energy use better, in reality it’s much more nuanced than that.
“Livestock production has its own set of problems, but in arable production the recurrent areas revolve around using nitrogen more efficiently, being mindful of the carbon footprints of products and inputs used and supporting on-farm renewable energy more.
“But there are other key factors which are often overlooked, such as reducing food waste and the role of productivity in the carbon equation.
“If you halve your carbon footprint, for example, but halve your production too, then the carbon footprint per tonne of production stays the same, so you can argue that’s not really addressing the issue.
“The characteristics of the crops you grow and the varieties you choose can affect your carbon footprint in a way we are only just starting to understand.”
1. Do not dismiss yield: While the recent direction of travel has been to focus on functional traits and agronomic features that make crop production easier to manage and more consistent, producers dismiss the future role of outright yield at their peril, says KWS UK country manager Will Compson.
“It’s absolutely essential that we breed varieties which are more resilient and can cope with the wider variations in growing conditions that are likely to be experienced as a result of climate change.
“But it’s equally essential that these varieties deliver financially.
The more you produce from a finite set of resources, the lower your cost of production per tonne and I think this is the way we need to be thinking in terms of carbon footprints.
“If you can produce 20% more yield from the same resources using one variety rather than another, that’s going to improve your carbon efficiency significantly.
“The last thing anybody wants is to drastically reduce the output of UK arable production, so in most years we are a net importer of grain. The food miles in that alone are likely to outweigh any carbon benefits we have made in the production of crops.”
Real benefits result when varieties are able to produce more from lower levels of carbon-intensive inputs, he adds.
2. Use disease resistance wisely: Disease resistance is an easy one to square up in terms of improving the carbon footprint of production, says Dr Richards.
“KWS Extase achieves an untreated yield of more than 10 tonnes per hectare in the 2021/22 RL and scores 8 for septoria resistance, so many people are thinking how they can cut back on fungicides and applications.
“The less you have to spray, the less diesel you will use and, of course, fungicides themselves are fairly energy-intensive to produce and there’s all the transport involved as well.
Fungicide programmes “I think it’s fair to assume the more disease resistance we build into varieties the less dependent they will be on fungicide programmes and the better that is for carbon footprints.”
Independent agronomist Bob Simons agrees, saying many growers are already finding they can cut out one spray application with KWS Extase.
“There’s little evidence of Extase benefiting from ‘heavy-duty’ spray programmes anyway, but a lot of people have found the variety does not need a T0 spray, unless yellow rust is prevalent.
“Just a low cost triazole does the job, if needed.”
3. Match variety to cultivation type: Min-till and no-till cultivation methods are becoming increasingly popular but the varieties you choose for these can have a big effect on the success of the system, KWS trials are showing.
“There are significant gains to be made by not using high levels of energy to plough or subsoil,” Dr Richards says.
“But the downside is often poorer yields which again potentially increase the carbon footprint per tonne of production.
Our latest trials suggest wheat varieties suited to later drilling could be the best bet for growers transitioning to no-till systems and provide greater protection against climate extremes.”
The trials compared fully ploughed cultivation systems to no-till across a range of popular varieties with KWS Extase and KWS Cranium, both later drillers with comprehensive disease resistance packages.
“Although the Group 2 variety KWS Extase was the highest overall yielder in both ploughed and no-till scenarios, Group 4 variety KWS Cranium was the highest yielder affected least by type of cultivation system.”
4. Focus on variety scheduling: The real benefits of modern breeding are only fully realised when key traits are integrated into a schedule, taking into account varietal performance throughout the year, says Dr Richards.
“You can create wide spray windows through the year to spread workload at key timings, bring them closer together for simpler, quicker management or mix and match intervals for sprays to suit individual farm workloads.
“In addition, you can ensure chemistry is applied at precisely the right time to get the best response from it so, combined with diseaseresistant varieties, you can optimise spray costs and disease control.
“And the same is true with harvest date.
Depending on your rotations, you can use variety and drilling date to create an early harvest, a more compact one or spread it out over summer to reduce pressure on machinery.
Applications “So, if you get your variety portfolio and scheduling right, chances are you’ll be using your chemistry more effectively, reducing applications and cutting back on diesel costs. All of which can significantly reduce your carbon footprint.”
5. Protect your soils: Systems of production that are kinder to soils than current ones have to be a priority in a more carbon-friendly future, adds Dr Richards.
“Reducing compaction through excessive machinery travel is key but we will also have to focus on nutrition practices that build organic content.
“More vigorous varieties that exert greater competition against weeds can reduce the need for heavy-duty cultivations and later drillers can help by giving enough time to deal with black-grass and other weed problems before they need to be drilled.
“Spring wheat varieties have come a long way in recent years and add further options, so in really bad autumns you can move a significant part of your drilling to the new year with the yield losses previously experienced.
“Early harvesting varieties can also extend the cultivation and drilling window to help you avoid having to work on land when soils are not in their best load-bearing condition.
“Soils are critical stores of carbon and a vital component of carbon sequestration for the future.
The better heart they are in, the more effective they are and the varieties you choose and how you manage them can have a profound effect on this.