Farms in England could reduce their energy-related carbon footprint by 8.8% to 13%, depending on farm type, simply by adopting nitrogen management practices that already exist, according to a study by Rothamsted Research published in the journal Food and Energy Security.
The study looked beyond the diesel and electricity used on the farm to the energy embedded in inputs, and found fertiliser manufacture to be the big one. On farms without livestock, emissions from producing fertiliser made up 39% to 47% of energy-related impacts. Best-practice nitrogen management would cut the indirect energy use tied to fertiliser by 16% to 40%.
Researchers modelled representative cereal, dairy, mixed, general cropping and lowland grazing livestock farms, comparing current energy use with a scenario in which they adopt established best practice. Average energy-related impacts ranged from 401kg of carbon dioxide equivalent per hectare a year on lowland grazing farms to 1,002kg on dairy farms. Better nitrogen use would also reduce eutrophication and acidification.
"Fertiliser production represents a substantial source of embedded (indirect) energy use, particularly for arable farming," said lead author Dr Y. Zhang. Science director Professor Adie Collins said the larger gains lay in tackling that embedded energy, for example with green ammonia made from renewable power, though its opportunities and risks, given the need for a steady renewable supply, still need strategic study.
The work was carried out under the Global Nitrogen Innovation Center for Clean Energy and Environment (NICCEE) programme. Rothamsted is now examining green ammonia production on UK farms and running life cycle assessments of different fertilisers.
For farmers anywhere who pay for nitrogen by the bag, the finding points the same way as the farm accounts: matching rate and timing to the crop saves both money and the energy that went into making the fertiliser.
Photo: Andy Beecroft (fertiliser spreading, East Riding of Yorkshire) / Wikimedia Commons (CC BY-SA 2.0)
Source: Seed World Europe
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