23 September
Dear Ruth Jones,
I am writing to you in your capacity as Shadow Minister for Agri-Innovation and Climate Adaptation. At present, Britain clearly has a long way to go to arrive at a sustainable system of farming. While piecemeal changes are being made, we are not seeing reform with anything like the pace and cohesiveness that we need to see. The urgency is derived from at least four key priority issues: the alarming rate of loss of agricultural soils and its subsequent threat to food security, the marked depletion of biodiversity related to agricultural practices, the need to engineer resilience in the food system to climate change and ecological shocks, and Britainâs legal commitment to achieve net carbon neutrality by 2050.
When I was studying ecology at Oxford a decade ago, there was a lot of valuable research being undertaken on ways of creating âmultiple winsâ for biodiversity, climate change and human factors simultaneously. Particularly where environmental externalities are concerned, there often seem so many trade-offs between competing priorities that progress can be mired in slow compromise at best and inaction at worst, so any opportunities for efficiently killing several birds with one stone with minimal downsides can be solid gold. Here, I want to bring up just one such potential opportunity for arable farming that I think has been largely overlooked.
Since 2008, the food system has decarbonised at less than half the pace of the wider economy, and the release of carbon from farmland soil is one of the major ways the food system contributes to climate change. In addition, the reliance on man-made fertiliser (particularly industrial ammonia) has created a dependence on a high-energy process using fossil fuels that by itself accounts for 1% of global carbon emissions. Once spread on farmland, much of that fertiliser is leached through the soil, where it goes on either to contaminate our water system or be converted by bacteria into nitrous oxide (which is about 265 times more potent than carbon dioxide) which adds a further 2% to global carbon-equivalent emissions.
In 2019, the government pledged to protect 30% of UK land âfor natureâ by 2030. On the tin, that sounds pretty good. Most viable plans to achieve that do however involve reclaiming a significant amount of farming land for afforestation or planting bioenergy crops that can then be processed using BECCS technology. The Climate Change Committeeâs (2020) model, for example, sees 21% of current farmland converted for sequestration by 2050. Some of the most suitable land for conversion produces little food anyway, but some has productive potential, and this represents an intensification at a time when two competing pressures are at play.
The first pressure is our reliance on food imports, which now make up almost half of Britainâs food consumption, compared to 78% self-sufficiency in 1984. This partly reflects changing tastes, but we certainly could stand to produce more of our own food, given that such reliance on imports leaves us vulnerable to global market shocks. But at the same time as needing to improve the countryâs overall yield, we need to arrive at more sustainable farming methods that prevent further loss of our precious soil and reverse the trend of biodiversity decline, while also meeting decarbonisation targets.
Until the Green Revolution, it was the norm for farms to grow mixed crops in rotations that included ruminant cattle (whose manure was an organic fertiliser), and for them to have plenty of hedgerows, and practices like these, as well as other, more ânature-friendlyâ methods, are very slowly making a comeback in what is these days being called âagroecologicalâ farming. This is broadly good stuff, but, as Defraâs independently commissioned National Food Strategy (2020) admits: âagroecological farming produces lower yields than modern intensive farming. We must somehow find a way to repurpose large areas of farmland, lowering yields in some places and returning others entirely to nature, while still producing enough to remain comfortably food-secure.â Quite the conundrum.
This brings me to a couple of potential opportunities for multiple wins, for soil conservation and decarbonisation, for biodiversity and for yields. What if we could eliminate the need for ammonia-based fertiliser? What if we could somehow actually improve on conventional yields through âecologicalâ methods? What if we could even improve the carbon capture potential of arable farmland itself? The potential to do that lies in what is going on beneath the surface of the soil.
A growing body of research over the last couple of decades has begun to identify the role of arbuscular mycorrhizal fungi (AMF) in plant growth. These fungi form networks in soil and form symbiotic relationships with the majority of plants, including most food crops. They increase the bioavailability of soil nutrients so plants can use them and grow more strongly as a result. They also produce a chemical called glomalin, which is important in aggregating soil particles, improving its structure and resistance to erosion. And they can act as bio-controllers too, reducing the numbers of microorganisms that are harmful to plants. They are pretty impressive organisms.
Several studies have shown that adding AMF as biofertilisers can reduce the need for artificial fertilisers (by up to 90%, depending on the plant), while increasing productivity by between 16-78%. At the same time, their bio-control function can reduce the application rate and frequency of pesticides. Reduced use of industrially-produced fertilisers in itself means a reduction in associated carbon emissions, but in some contexts, AMF may also contribute to carbon sequestration, actively drawing carbon dioxide from the atmosphere and storing it in the fungi and in the soil.
Much of the research on the carbon storage potential related to AMF has focused on forests, which have a different ecology to an agricultural field. What we do know though is that tilling destroys these fungi (along with many other useful microorganisms), so the longer soil goes undisturbed, the more chance their networks have to establish. In old forests, AMF networks can be hundreds of years old and stretch for miles â making them the largest organisms on the planet â and all that biomass, plus the glomalin-related soil protein produced in the fungal cell walls, represents a vast carbon store. Any potential for AMF to actively store carbon over the long term is likely supported by a lack of soil disturbance. Rather than repeated annual applications as a biofertiliser, then, we could introduce initial inoculants and allow them to establish over many years. While simple no-till farming could support this to an extent, better still would be a union with perennial polyculture, which itself promises to deliver multiple wins.
Perennial polyculture shifts planting plans from fields full of a single, annual crop (monoculture) to arrangements involving several perennial crops that are interplanted. The benefits of this are many, and include increased biodiversity, increased crop resilience to pests and disease, reduced need for herbicides (due to fewer weeds) and reduced soil erosion. Research by the Land Institute and the Rodale Institute demonstrates that these arrangements can also substantially increase yields versus annual monocultures. The inclusion of leguminous crops in polycultures (which are able to âfixâ nitrogen from the air) could also partially or even completely remove the need to apply external nitrogen fertiliser, while the establishment of mycorrhizal networks would ensure a high bioavailability of soil nutrients to crops and may also restore soils and store carbon over the long term.
This level of systemic redesign goes beyond what most policymakers currently consider when they talk of âagroecology,â but it could really be a game changer. There are some challenges in such an overhaul of conventional farming, including R&D matters of developing a greater number of commercially viable perennial crop varieties and adapting technology to facilitate efficient harvesting in polycultures, plus the hurdles of cultural transformation. I suggest that the development and implementation of perennial polyculture methods should be a top priority in order to achieve a truly sustainable food system. This would involve not just active sponsorship of programmes by the government, but a much greater strategic integration of what is currently still a very disparate web of research and practicing farmers with the private sector and the wider farming community to arrive at an implementable plan and a collaborative effort to transform the way we grow food.
Would Labour be onboard with such a vision and strategy for integrative research and practice that could see Britain lead the world on food sustainability?
 Yours sincerely,
Christopher Crompton
Christopher Crompton