Minimising cultivations, lowering grain drying requirement, reducing synthetic fertiliser inputs and using urease and nitrification inhibitors can reduce a crops carbon footprint by up to 41 per cent while sustaining yield, according to data from YEN Zero.
The new grower network jointly launched by ADAS, which runs the Yield Enhancement Network (YEN) and a collective of agricultural organisations, calculated the crop carbon footprints of 50 UK farms based on their agronomic practices and yields.
Subsequent benchmarking uncovered a large variation in greenhouse gas (GHG) emissions across farms.
Taking a typical wheat crop, the highest footprint recorded was 5,658kg CO2e/hectare and the lowest was 625kg CO2e/ha.
By 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 per cent while sustaining yield.
Direct drill
Using the average carbon footprint of winter wheat feed crops of 2,724kg CO2e/ha, it was shown that moving from a plough-based to a direct drill cultivation system could cut fuel use and reduce a crops carbon footprint by 9 per cent.
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 per cent.
Nitrogen
Predictably, higher carbon footprints were associated with a strong reliance on artificial nitrogen. 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 165kg N/ha, with no difference in average yield.
When only considering fertiliser manufacture emissions, this reduction in fertiliser use can reduce a fields carbon footprint by 9 per cent, says Dr Christina Baxter, ADAS consultant andYENZeronetwork lead.
Artificial N fertiliser contributes over half of a wheat crops carbon 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, optimising application timings, and using urease and/or nitrification inhibitors where appropriate.
Footprint
Lincolnshire grower Colin Chappell, who took part in the YEN Zero pilot year, says YEN Zero has allowed him to give grain purchasers a definitive measure of his grains carbon footprint per tonne.
More than that though, through debate around figures, we can work on ways to reduce the figures even further, he adds.
To develop the YEN Zero network, the pilot year has been run on a partially closed basis, but going forward, it will be opening fully to growers, agronomists, and agricultural organisations.
