The Underground Solution: soil's impact on carbon sequestration and the food industry

In 2002, the International Union of Soil Sciences initiated a global effort to establish an international day dedicated to celebrating the importance of soil. Recognising its significance, the FAO prioritised this cause in 2013, and by the close of that year, the UN General Assembly officially designated December 5, 2014, as the inaugural World Soil Day. The purpose of such designated days is to generate political support and allocate resources for addressing issues that affect people's livelihoods on a global scale.

The central message conveyed on World Soil Day is that businesses can contribute to soil health, leading to synergies with carbon reduction, land restoration, and water conservation. However, it emphasises the necessity of reliable data to discern which farming and restoration methods have the most significant impact.

Approximately one-third of the Earth's soil has suffered degradation and depletion due to human activities, impairing its ability to sequester greenhouse gases. The intricate scientific relationships among our food, soil, and prolonged land mismanagement paint a concerning outlook for the future.

Despite these challenges, there is optimism regarding the potential transformation of our fragmented food system with the use of science, soil, and data.

For those who are curious, it's essential to recognise the intrinsic connection between our soil and the food we consume, whether it's the vegetables grown on the earth or the meat derived from livestock grazing on grass.

If you remain unconvinced, here are some key facts about the profound relationship between soil and our food from the FAO*.

• 95% of food comes directly or indirectly from soil (including feed for animals)
• Healthy soil may mitigate climate change by maintaining or increasing soil organic carbon
• Land-use conversions and drainage of organic soils for cultivation are responsible for 10% of all greenhouse gas emissions
• Healthy soils can help to manage and control pests, insects and plant disease
• Nutrient-rich soils produce nutrient-rich foods
• Soils host a quarter of Earth's biodiversity 

A brief climate science lesson on our soil systems

Carbon stored in soils is pivotal for mitigating greenhouse gas emissions and is fundamental to the global carbon cycle. Our soil acts as a carbon sink, sequestering various forms of carbon. Organic soils consist mainly of decomposed plant and animal matter, which can have a higher carbon content than mineral soils, influencing the soil's properties and suitability for various agricultural purposes. As depicted in Figure 1 below, the proportion of organic soil is much lower than the proportion of mineral soils in the EU. Understanding that organic soils play a more crucial role in carbon storage than mineral soils strengthens the critical nature of sustainable management of organic soils.

As illustrated in this video, based on soil in Hawai’i but applicable globally, carbon in soils undergoes dynamic cycles and practices. It is continually absorbed through plant photosynthesis, released through decomposition, and transformed into stable organic forms for storage. Natural factors such as temperature and moisture affect soil carbon dynamics, but human activities, such as deforestation, biomass burning, and changes in land use, play a significant role in greenhouse gas emissions from the soil. Human activities that impact the soil can result in the release of more greenhouse gases (GHGs) into the atmosphere. Soil microbes decompose organic matter in the soil, releasing CH4 (methane), CO2, and NO2.‍

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If our soil is in such dire need of attention, what can policy do?

Existing policies in the UK and EU cover various areas, such as water, waste, chemicals, industrial pollution prevention, nature protection, and pesticides. However, a critical gap exists in data collection, particularly regarding soil carbon storage trends. Monitoring these trends is essential to inform policy decisions and assist food businesses in making impactful moves against soil deterioration.

‍What can food businesses do?

Our top recommendations would be to investigate and invest in a life cycle assessment, look into your supply chain to discover where sustainable farming practices can be included and utilise highly rigorous data tools.

Let's break that down.....
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Life Cycle Assessments: Many food businesses are using farm-level life cycle assessments to understand their soil quality and assess the impact of land use on its health. Some are involving their supply chains to revamp their land utilisation, with a few opting for more sustainable agricultural practices like regenerative farming. Later, we will elaborate on the practices that these food businesses may currently employ or plan to adopt in the future, with a specific emphasis on soil management. If you’re ready to explore what a life cycle assessment might look like for your business, please do get in touch. ‍

Utilising rigorous data tools: Hestia, a project which Foodsteps contributes to and supports, addresses the lack of data on environmental impacts on food production. It collects and shares detailed and harmonised data on greenhouse gas emissions from farming, filling a crucial gap in understanding the nuances of different farming methods, including how soil management practices affect the emissions per unit of output product. This information is valuable for researchers, farmers, businesses in the food supply chain, and organisations working to combat climate change. This is essential because the farming stage is typically the main contributor to a food product's life cycle emissions, outweighing processing, packaging and distribution. As well as allowing us to conduct industry-leading environmental impact assessments, Hestia will be a key resource in driving higher-quality data across food impact assessments. For example, it could improve the data available in resources such as the WRAP Scope 3 Emissions Factor Database, which Foodsteps helped to release and update over the last two years.

What sustainable soil management practices are currently available? 

Maintaining forest and peat systems regeneratively: Protecting ecosystems is vital for preserving their biodiverse soils and their superior carbon capture capacity compared to other land-use methods. This is crucial because human activities have impacted almost all forests and peatlands worldwide, altering not only the above-ground ecosystems but also the soil ecosystems and their carbon retention capabilities. Peatlands, storing around 44% of the world's soil carbon, are the focus of significant projects aimed at protection, conservation, and restoration. Some researchers are experimenting with innovative farming methods, such as paludiculture, to restore the carbon capture ability of previously dried peatlands.

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‍Cover crops to protect soil and zero tillage: Tillage is when we turn the soil to deal with weeds and pests and get it ready for planting. But, intervening too much with the soil can cause problems in the soil's ecosystem. Some farming methods, like digging too deep or removing too many plants, can make the soil lose important things like nutrients and microorganisms. This interferes with the soil's balance and makes it hard for the soil to hold onto and absorb carbon. So, it's important to find ways to farm that don't disturb the soil too much and use cover crops to keep carbon and nutrients in the soil.‍

Crop rotation and mixed cropping: Having just one type of plant in an area, called monoculture, can disrupt the soil. When there's only one kind of plant, it takes up certain nutrients from the soil and attracts specific microorganisms. This makes it hard for other helpful microorganisms to thrive. To make up for the lost nutrients, people often add fertilisers and pesticides, which can throw off the natural balance of the soil and make it less healthy. In places with only one type of plant, soil is less resilient. Traditionally, agricultural communities have rotated crops to avoid affecting the ecosystem, so it can recover and be restored. Rotation practices vary depending on the land and the crops grown but increasingly intercropping is seen as a solution allowing farmers to have a more continuous stream of income without needing to switch their land-use practices drastically from one year to the next. One such ancient system has gained particular attention and is often used within permaculture land use and is referred to as the three sisters method. This indigenous agricultural method originates in North America and usually pairs maize, beans and squash. There is evidence that combining different types of plants can have multiple benefits, such as complimentary resource use of plants leading to reduced need for fertilisers, better protection to plant pests and greater soil stability.  ‍

Mob grazing methods: People are still figuring out the best way to use mob grazing to trap carbon in the soil. A recent study looked at different effects on soil carbon during mob grazing, but there's no clear agreement yet. Mob grazing needs more land compared to other ways of raising animals, like keeping them in pens. This could be a problem because using more land might lead to cutting down more trees and harming protected areas. We need to look at the whole food system to understand how to feed people without further disrupting nature's ability to regenerate. Some studies suggest producing a lot of food in a small space as a solution to save land for nature.

How can we navigate the nuances going forward?

Taking care of the soil is crucial, especially when it comes to carbon levels, as our environment is constantly changing. To address challenges from climate change, we're adopting better soil practices like keeping forests and peat systems, using cover crops, rotating crops, planting different crops together (intercropping), and using mob grazing methods. But to understand how these practices affect farms, we need lots of data and smart analysis. The details hidden in the data require a careful approach to uncover the little things that make farms sustainable.

Currently, the general methods of looking at data can't fully understand all the details. Farming is complicated with different crops and regions, making it hard to accurately figure out greenhouse gas emissions without more specific information. Even though it's uncertain, we need to keep researching. By finding better ways to study and use new technologies, we can collect more data and get a clearer picture of how soil health and greenhouse gas emissions connect on individual farms.
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How are Foodsteps and our database helping to move the needle on soil data? 

Previously, we highlighted our ongoing collaboration with the Hestia project to enhance our understanding of complexities and data gaps in the farm-to-fork journey of our food. Through such partnerships, we can leverage data to advise food businesses on proactive changes in their supply chain, such as shifts in production practices to further reduce carbon emissions. These collaborations also contribute to developing standardised assessment methods for better benchmarking of business impacts and information for policymakers.

At Foodsteps, data plays a crucial role in comprehensively analysing the carbon impact of food and drink. By embracing insights from data analysis, we can gain a deeper understanding of ecosystem complexity and promote a holistic approach to soil management that recognises the various factors influencing soil carbon levels.
If Foodsteps feels like  a suitable data partner for food businesses working to lower their environmental impact, please do get in touch.
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This piece was co-written with help from Josephine Millen, Joe Duncan-Duggal, Dehaja Senanayake.

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Sources: Rowntree et al., 2020, Roberts and Johnson, 2021, Bamford, 2021, Gervasio Piñeiro et al., 2010, K. L. Greenwood and B. M. McKenzie, 2001, Heuser, 2022, EEA, Cambridge University, Zoological Society London