How can UK farming reach net zero?

UK farms are estimated to emit 45.6 million tonnes of carbon dioxide equivalent each year (MtCO2e/year), amounting to around 10% of UK greenhouse gas (GHG) emissions. The National Farmers’ Union (NFU) have set out their plan1 for reaching net zero by 2040 by changing the way that agricultural land is managed. They estimate that changes to land use and farming practices could enhance soil carbon storage delivering GHG savings of 5 MtCO2e/year. 

Project Drawdown is a large collective of researchers whose mission is to help the world reach the ‘Drawdown’ point, where net GHG emissions go negative. Removing more GHG emissions than we emit could help avoid the worst effects of climate change. In order to achieve this, Project Drawdown has collected extensive research into practical solutions that can be implemented now. In their agricultural research they estimate that globally at least 50% of the carbon from soils has been released into the atmosphere over the past centuries. Below is a summary of the project’s proposed solutions that are most relevant to enabling UK agriculture to reach net zero.

Nutrient management2

Careful nutrient management reduces the risk of excess nitrogen fertiliser increasing land nitrous oxide emissions, which have a warming effect 298 times that of carbon dioxide. Excess nitrogen can damage organic matter in soils and leads to polluted waterways, resulting in algal blooms and oxygen depletion. Due to potential harms to public health, 30% of groundwater supplied to households is now treated for nitrate, at significant cost, in order to meet tap water standards. The Environment Agency reported  that 55% of England is now designated as a Nitrate Vulnerable Zone, where excess nitrate is contributing to water pollution, with 70% of the nitrate originating from agricultural runoff. With climate change, more frequent storm events are predicted to increase nitrate runoff.

As with most pollution challenges, prevention is much simpler and more affordable than cure. One solution is to apply less fertiliser more strategically, by supplying the fertiliser blend most appropriate to the crop, at the right time, in the right areas, and at the right rate. However, the ideal would be to replace much of the artificial fertiliser in use with regenerative land practices, a transition that is supported by a range of government grants and services.

Efficient irrigation4

While much of the UK does not require irrigation, there is significant usage in the midlands, east and southeast of England. Three quarters of the volume of water used to irrigate agriculture and horticulture is sourced from catchments that are already experiencing severe water stress. Climate change is expected to lead to more frequent and severe droughts, increasing competition for reduced water resources. This area is strongly impacted by policy. Allowable abstraction rates need to be well-managed to meet the needs of agriculture, in balance with other sectors, without doing harm to the environment. Further information on UK irrigation is provided in a report funded by the UK Irrigation Association5.

Improving irrigation efficiency increases crop yield while decreasing soil erosion. It is not only important due to the need to manage water supplies, but also the energy required to pump and distribute the water. If irrigation is required to maximise yields, the environmental impact can be limited by using it in a targeted manner, reducing carbon dioxide emissions from energy consumption and optimising water usage using precision agriculture.

Managed grazing6

Managed or conservation grazing focuses on optimising livestock grazing and the timing and intensity of grazing. Managed grazing imitates the behaviour of migratory herds, specifically, having limited periods of livestock grazing on an area followed by allowing the land to rest before animals return. Project Drawdown suggest 3 levels of managed grazing6 that aim to improve soil health, sequester carbon, and enhance water retention and forage productivity:

• Improve continuous grazing by adjusting standard practices and reducing the density of animals.

• Apply rotational grazing with livestock moved between fields, allowing those recently grazed to recover.

• Introduce adaptive multi-paddock grazing where livestock are moved between smaller paddocks in quick succession, allowing greater recovery time between periods of grazing.

Using such techniques can be very good for soil health and may sequester from 0.5 to 3 metric tons of carbon per acre. Both Defra and Project Drawdown provide guidance on how best to approach conservation grazing and how it can benefit wildlife7.

Conservation agriculture8

Conservation agriculture is a system of growing annual crops that uses cover crops, crop rotation, and minimal tilling to protect soil, avoid emissions, and sequester carbon. Due to the large area of land currently used to grow annual crops, conservation agriculture has the capacity to sequester significant amounts of carbon in soil even though the rate of sequestration isn’t the highest at about 0.5 metric tons of carbon per acre. Additionally, conservation agriculture increases soil resilience to weather events such as droughts and rainfall-induced flooding, expected to be exacerbated by climate change.

A common concern with no tillage approaches to agriculture is the increased need for herbicides, as weeds will no longer be disrupted by tillage. Conservation Agriculture UK estimates that the money saved by direct drilling with no tillage (instead of potentially multiple tillage operations plus seeding) covers or exceeds the additional cost of the direct sowing machinery and increased herbicide use, while increasing crop yields and reducing labour costs9.

Regenerative annual cropping10

Conservation agriculture can be taken a step further to achieve increased soil organic matter with further reductions in emissions and more carbon sequestered by utilising regenerative annual cropping. This seeks to enhance the health and productivity of soil by enhancing its carbon content by building on the practices of conservation agriculture with:

• no external nutrients / synthetic fertilisers applied

• no pesticides 

• diverse crops 

• utilising grazing animals

Project Drawdown reports that regenerative annual cropping enables vital microbes to proliferate, roots to grow deeper, increased nutrient uptake and water retention, and increases in both pest resistance and soil fertility. They calculated the carbon storage to be in the region of 0.4-1.4 metric tons of carbon per hectare per year (climate dependent).

In the UK, the Groundswell group11 holds an annual regenerative agriculture event and reports interest growing both within the agricultural sector and amongst policy makers. It is expected that the new government Environmental Land Management Scheme will support and financially reward farmers for moving to regenerative techniques.  

References:

1: NFU net zero plan https://www.nfuonline.com/updates-and-information/achieving-net-zero-meeting-the-climate-change-challenge/

3: EA nitrogen report https://consult.environment-agency.gov.uk/++preview++/environment-and-business/challenges-and-choices/user_uploads/nitrates-pressure-rbmp-2021.pdf

5: UK irrigation report https://www.ukia.org/resources/

7: Defra guidance on conservation grazing https://defrafarming.blog.gov.uk/graze-with-livestock-to-maintain-and-improve-habitats/

9: Conservation Agriculture UK http://www.conservation-agriculture.co.uk

11: Groundswell Group https://groundswellag.com/principles-of-regenerative-agriculture/

Project Drawdown References:

2: Nutrient management https://drawdown.org/solutions/nutrient-management

4: Efficient irrigation https://drawdown.org/solutions/farm-irrigation-efficiency

6: Managed grazing https://drawdown.org/solutions/managed-grazing

8: Conservation agriculture https://drawdown.org/solutions/conservation-agriculture

10: Regenerative annual cropping https://drawdown.org/solutions/regenerative-annual-cropping