YEN benchmark reveals crop carbon footprints

Growers could cut a crop’s carbon footprint by up to 41% while sustaining yields, by measures including minimising cultivations, lowering grain drying requirement and reducing synthetic fertiliser inputs.

Results of the first year’s YEN Zero benchmarking initiative have revealed a large variation in greenhouse gas (GHG) emissions across farms.

Taking a typical wheat crop, the highest footprint recorded was 5,658 kg CO₂e/ha (CO₂ equivalent per hectare), compared to the lowest at 625 kg CO₂e/ha. Examining the practices of the most efficient performers, YEN Zero has revealed the most effective on-farm carbon mitigation strategies – a combination of which could allow farms to lower their footprint by up to 41% whilst sustaining yield, reports Dr Christina Baxter, ADAS consultant and YEN Zero network lead.

YEN Zero, a new grower network jointly launched by agricultural consultant ADAS, along with Syngenta and a collective of agricultural organisations, calculated the crop carbon (C) footprints of 50 UK farms based on their agronomic practices and yields.

Using the average carbon footprint of winter wheat feed crops of 2,724 kg CO₂e/ha, it was shown that moving from a plough-based to a direct drill system could cut fuel-use and reduce a crop’s carbon footprint by 9%.

In addition, the fuel required at harvest to reduce grain moisture content significantly increased overall emissions. By harvesting grain at the right time to avoid any drying needs, carbon emissions could be reduced by a further 11%.

The YEN Zero benchmarking results reinforce many of the agronomic, economic and environmental gains seen over five years with the Syngenta Conservation Agriculture project.

Predictably, higher C footprints were associated with a strong reliance on artificial nitrogen (N). Growers of winter wheat feed crops with the highest GHG intensities were found to have applied on average 212 kg N/ha. Growers with the lowest GHG intensities tended to apply on average 165 kg N/ha, with no difference in average yield. When solely considering fertiliser manufacture emissions, this reduction in fertiliser use can reduce a field’s carbon footprint by 9%.

Dr Christina Baxter explained “Artificial N fertiliser contributes over half of a wheat crop’s C footprint. However, this can be substantially reduced through improving nitrogen use efficiency through; measuring levels of mineral N in the soil, only applying what the crop needs and optimising application timings, along with using urease and/or nitrification inhibitors where appropriate.”

Commenting on the first year’s results, Belinda Bailey, Syngenta Sustainable Farming Manager, said: “The immense scale of the YEN Zero initiative provides an incredibly valuable insight into carbon footprinting across the whole farm rotation, and the implication of crop yield in minimising farming’s impact per tonne of production.”

“YEN Zero results will help to focus our future research and developments in measures that will reduce carbon emissions at all stages of the crop production cycle, as well as the data and science to build the positive gains that agriculture can deliver for carbon sequestration into the calculations,” she added.

Lincolnshire grower Colin Chappell who took part in the YEN Zero pilot year highlighted: “Some of my purchasers are now starting to ask for my carbon footprint; having joined YEN Zero, I have a definite answer per tonne that I can pass back to them.

“We can work on ways to reduce the figures even further.”

Fellow participant Suffolk grower Mark Harrington added: “Taking part in YEN Zero enabled us to see not only where our carbon usage was high but also high carbon equals higher costs.

“If we are able to carry on recording inputs on the same fields throughout the whole rotation sequence over a number of years, then we will be able to benchmark each year against our own performance on the same soils etc as well as comparisons with other farms”

Christina Baxter added: “Being part of this collaborative endeavour across the whole supply chain, to uncover carbon reduction strategies that really work, has been so exciting. Thanks to our industry sponsors whose support has been vital for getting YEN Zero off the ground, and to the growers that took part.”