What impact does organic farming have on climate change?
Organic farming offers the best, currently available, practical model for addressing climate-friendly food production:
Sequestering carbon in the soil
Agriculture can make a significant contribution to mitigating climate change by taking carbon out of the air and sequestering it in the soil. Our research shows how the widespread adoption of organic farming practices in the UK would offset 23% of UK agricultural emissions through soil carbon sequestration alone, more than doubling the UK Government’s pathetically low target of a 6-11% reduction by 2020. On average organic farming produces 28% higher levels of soil carbon compared to non-organic farming in Northern Europe, and 20% higher for all countries studied. (Soil carbon and organic farming, [PDF 2.07 MB])
The soil carbon benefit of organic farming results from the fact that the system is based on inputs of organic matter to the soil and the decomposition of this by soil microbial activity for releasing nutrients for crop production, instead of using inorganic fertilisers. This process at the same time produces humus (stable soil carbon) and thereby raises the soil’s carbon levels.
The use of manufactured fertilisers is not allowed
Manufactured nitrogen fertilizer production, using the Haber-Bosch process, is reliant on fossil fuels, mainly natural gas and some coal. These are used as a source of hydrogen and as a fuel for the chemical process. It is estimated that fertiliser production is responsible for about 1.2% of the total emission of the greenhouse gases (GHG) in the world.
Organic farms cannot use manufactured nitrogen fertiliser so they avoid the GHG emissions from its production, and transportation. Instead new nitrogen for growing crops is obtained by using legumes such as clover that can ‘fix’ nitrogen from the atmosphere.
The use of manufactured nitrogen fertilisers causes increased emissions of nitrous oxide (N2O) a greenhouse gas nearly 300 times more powerful than carbon dioxide. N2O emissions make up over half of the GHG emissions from UK agriculture.
Organic farming also releases some N2O, especially when nitrogen-fixing legumes are ploughed in. Scientific research is limited, but current evidence shows that the lower nitrogen inputs in organic farming systems can lead to lower N2O emissions compared to non-organic farms on an area basis. The Soil Association is asking the Government for further research into understanding how nitrogen behaves in organic farming systems.
Resilience in the face of climate change
In the future our farming systems will need to be able to cope with climatic variability. There is evidence that organic farming can have advantages in drought-conditions, such as higher yields compared to non-organic systems, because of the higher water-holding capacity of soils under organic management.