Written evidence submitted by Professor Nick Voulvoulis and Dr Bonnie Waring (SH0019)


House of Commons Environment, Food and Rural Affairs Select Committee Soil Health Inquiry Submission 


Explanatory note:  

This response has been developed by Imperial colleagues from across the College’s expertise.  
In this submission, the full names of contributing researchers will appear at the beginning of their first answer and any subsequent answers will begin with their initials. A full list of contributors is included at the foot of the document.  


  1. How can the Government measure progress towards its goal of making all soils sustainably managed by 2030? What are the challenges in gathering data to measure soil health and how can these barriers be overcome?


Dr Bonnie Waring (BW): ‘Soil health’ is a nebulous, context-dependent term without a clear definition; therefore, it cannot be directly measured and tracked. Should soil health be defined in relation to a 'reference' ecosystem which is relatively unmodified by humans, such as an unmanaged grassland or forest? Or is soil health associated with its capacity to support ecosystem services needed by people, such as food or fibre production? These operational definitions may come into conflict; for example, the extremely low-nutrient soils underlying intact Amazonian campinarana forests or Florida sand pine scrub may be ecologically undisturbed and therefore, by some definitions, ‘healthy.’ However, these same soils would not support productive agriculture. Individual parameters that are often measured and discussed in relation to soil health – organic matter content, soil structure, and soil biodiversity – cannot reveal the degree to which various soil functions have been disturbed, or the capacity of soils to recover in the future. To build a dashboard of appropriate indicators which can be tracked to monitor soil status in the UK, it is first necessary to develop a rigorous definition of soil health.


Professor Nick Voulvoulis (NV): Soil protection and its sustainable management has featured in policy discussions around the world for the last few decades, however soil policy has not followed the same development pathway as air and water policy and has been less advanced.  There has been an increased interest in the need for managing and protecting soils due to increased pressure on land for critical socioeconomic activities, the emerging impacts of climate change as well as due to increased understanding of the threats from degradation processes, calling for the development and implementation of soil protection policies. Historically, within the EU although soil protection was covered by some sector-related policy measures such as the Sewage Sludge Directive (1986), the Integrated Pollution and Prevention Control (1996), waste management laws, chemicals law, and air pollution law, there has been no specific legislation relating to soil protection. In 2006, the EU did adopt the Soil Thematic Strategy, providing a common framework for soil protection, but the proposed Framework Directive for the protection of soil (required integration of soil protection into all policy making, prevention of degradation and pollution of soils, implementation of risk/priority areas with action programmes for soil threats, containment of soil sealing, and identification and remediation of contaminated sites) was never agreed upon, with much opposition on the grounds of subsidiarity and proportionality, expected costs and administrative burden (much of it coming from the UK). As a result, there is currently still no comprehensive legal instrument on soil protection in the EU, with a potential soil health law expected to be in place by 2023 to bring soil on the same legal footing as air and water (see: From Chemical Risk Assessment to Environmental Quality Management: The Challenge for Soil Protection, Environ. Sci. Technol. 2011, 45, 1, 104–110)

Soil is an environmental medium that is often neglected, partly because there is no widespread understanding of the importance it has for ecosystems and the economy. This ultimately comes down to the lack of a clear definition of soil, and the more complicated issue of defining or assessing its quality (or health). The links to the environment and human health are not evident for soil to the same extent as water and air. In order to measure soil health and potential improvements as a result of soil management and policies, there is therefore a need to clearly define soil, its state of degradation and what is meant by the term soil quality /soil health (see: Public Participation in Soil Surveys: Lessons from a Pilot Study in England, Environ. Sci. Technol.  2012, 46, 7, 3687-3696).  In the past, as part of a research project, at Imperial and in collaboration with BGS and the Environment Agency we proposed a definition of soil quality incorporating soil's ability to meet multifunctional requirements, to provide ecosystem services, and the potential for soils to affect other environmental media (See: Soil quality assessment under emerging regulatory requirements, Environment International, 36 (2010), 609-622). While the assessment of soil health based on this definition requires a large number of soil function dependent indicators that can be expensive, laborious, prone to error, and problematic in comparison, we also demonstrated the benefits of a method that is not function dependent but uses several cross functional indicators instead. This method was based on a step to systematically prioritise areas where detailed investigation is required, using a ranking based against a desired level of action, that can be relatively quick, easy and cost effective (see: Prioritising soil quality assessment through the screening of sites: the use of publicly collected data. Land Degrad Dev, 2014, 25: 251-266). 


  1. Do current regulations ensure that all landowners/land managers maintain and/or improve soil health? If not, how should they be improved?


NV: The current UK legislative landscape related to soil is a confusing patchwork of Acts, schemes and initiatives, that shares the same problems with previous EU initiatives and is by no means an alternative to soil protection policy. All three proposed schemes (The Sustainable Farming Initiative, The Local Nature Recovery scheme, and The Landscape Recovery (LR) scheme) suffer from not defining what the end goal is in relation to soil quality and health.

To address this, the government needs to develop a shared vision of what our landscapes should look like in a net zero world, and a clear set of sustainability strategies based on scientific evidence and backed by investment. It needs to be a nature-positive vision not undermined by importing food produced to low environmental standards. For this, it needs to also target not just farmers and landowners but food businesses, including supermarkets, that have significant influence over how food is produced (see; Systems thinking as a paradigm shift for sustainability transformation, Global Environmental Change, 2022, 75, 102544-10254).

Land managers and landowners (including farmers, foresters, gardeners, local/regional authorities, spatial and urban planners) often do not sufficiently apply or promote practices that maintain and/or restore soil health because of a lack of knowledge and tailored advice on locally adapted practices. Impartial advisors with ample theoretic and practical knowledge on soils, their functions and management could help address this, although there is a more fundamental need for understanding soil health and ensuring that the knowledge needed is constantly updated, standardised to some extent and responds to the evolving needs of land managers and policies.  We need the development of a comprehensive toolbox of resources for the training of land manager/owners and their advisors and a set of tools and strategies (including financial models) to ensure that they adopt practices that improve soil health.


BW: I will focus my comments here on the Sustainable Farming Incentive (SFI), which provides guidance on how land managers should assess soil health and how they should enhance it. The SFI guidelines currently recommend that farmers visually assess soil texture, structure and biodiversity (by counting soil fauna), and evaluate risk of erosion and nitrogen leaching through considering landscape features and soil type. Many of these evaluations are not likely to yield useful data that can be tracked over time. For instance, evaluating the presence of earthworms, millipedes, and spiders in just a handful of samples is largely pointless, due to the patchy distribution of these organisms (both across the landscape, within a farm and over seasons), and because most soil functions are driven by microscopic or cryptic organisms (e.g., nematodes, mites). More concerning, however, is the fact that the SFI guidelines do not encourage farmers to rigorously evaluate their practices with respect to synthetic fertilizers, herbicides, pesticides, manure, or other inputs. These inputs are responsible for many of the negative impacts of agriculture both on and off-farm. As just one example, at the global scale, synthetic fertilizers account for 2% of global greenhouse gas emissions[1] and the resulting volatilization of nitrogen has deleterious impacts on non-agricultural systems, particularly ancient woodlands.

The actions recommended under the SFI to improve soil quality are adding organic matter, providing winter cover/minimizing bare ground, and establishing herbal leys in improved grassland. Minimizing bare ground and cover cropping is a very practical, common-sense measure to reduce erosion and enhance soil organic matter content. However, this set of actions is limited, and does not spur farmers to maintain or increase yields while reducing inputs – which is going to be necessary to meet national and global targets for climate mitigation[2]. These actions could also be better tailored and made more specific in order to maximize ‘win-win’ outcomes with respect to other ecosystem services (e.g., through sowing pollination-friendly seed mixes in herbal leys to counteract bee declines).


  1. Will the standards under Environmental Land Management schemes have sufficient ambition and flexibility to restore soils across different types of agricultural land? What are the threats and opportunities for soil health as ELMs are introduced?


NV: Sustainable food systems are underpinned by a healthy environment and thriving wildlife, so the Environmental Land Management schemes aim to restore degraded landscapes and make space for wildlife through payments to farmers. However, ‘making space for nature’ within the farmed landscape and the wider countryside is not an alternative to the transformation of the food production systems needed for sustainability. “Oases for nature” surrounded by intensively farmed deserts will be worse for the environment. Public money for public goods is the right framework for the new payments system but will not deliver the transformative changes needed. To reverse widespread declines in wildlife and natural systems, we must start producing food much more sustainably.  Farmers need support to innovate and adopt new practices that will enable them to produce food in ways that contribute to the restoration of the natural environment and meeting the UK’s carbon targets.


BW: ELMs will need to more carefully consider the interactions among the Sustainable Farming Incentive, the Local Nature Recovery scheme, and the Landscape Recovery scheme. Most of the actions under the SFI, at present, seem aimed at enhancing soil organic matter content and reducing erosional losses. This is a common-sense approach, given that soil organic matter content is positively associated with crop yield[3], and because soil degradation is a serious threat to UK agriculture. However, taken in isolation, these SFI activities will not necessarily reduce the climate impacts of agriculture, enhance the biodiversity of the soil food web, or counteract increasing reliance on chemical inputs. Depending upon the rewards to the farmer from the SFI vs. Nature Recovery, the Government may incentivize widespread adoption of more incremental management changes with relatively minor environmental impact, or spur bold, transformative actions that centre less on management of existing croplands and pasture, and more on nature restoration.

  1. What changes do we need to see in the wider food and agriculture sector to encourage better soil management and how can the Government support this transition?


NV: Developing sustainable farming practices and building profitable farming businesses are not different things. Environmental degradation diminishes the capacity to sustain economic development, and we need high environmental standards, to shift to more sustainable food production systems. These systems will need to deliver in both fronts by cutting carbon emissions, improving soil health and biodiversity, water quality and flood resilience, while boosting the productivity and profitability of farming. Such changes for sustainability involve fundamental redirections of current human-environmental interactions, requiring coordinated policy, technology, behaviour and market interventions. There are no simple answers or silver bullets, but we need to embrace the complexity of these problems and work with farmers to deliver system transformation by accelerating the development of policies for large-scale social, political, institutional and behavioural change. For example, high environmental standards for production at the UK, along with similar standards for food imports, are essential preconditions for an agricultural policy that protects and improves the environment.


BW: The highest-level challenge for the Environmental Land Management scheme is to consider the UK agricultural sector in the context of its global impacts, many of which are indirect and diffuse. To provide a tangible example, organic farming practices are often seen as a benefit for the environment, because fewer pesticides and herbicides are used. However, Smith and colleagues[4] showed that, if England and Wales were to convert entirely to organic farming practices, large areas of forest and native grassland outside the UK would need to be converted in order to support domestic food consumption. This is because most organic systems are not as productive as conventionally managed farms and pastures. Despite the potential benefits of more ‘environmentally friendly’ farming practices, these same practices may displace deforestation or other harmful environmental practices onto biodiversity-rich areas overseas. Therefore, any policy structures aimed at improving soil health must be integrated with bigger-picture strategies to reduce meat consumption (which has disproportionate impacts on land use conversion and agricultural greenhouse gas emissions), to improve crop yields through technological innovation (thereby sparing additional land use conversion), and to reduce the use of biocides and antibiotics which lead to health problems in humans and other organisms.


  1. What does UK Government need to do to tackle other stressors on soil health such as soil contamination?


NV: One of the challenges for policy makers tasked with the protection of soil is the need to transition toward more holistic management. For soil this is difficult as contaminated land which focuses on the presence, movement, and availability of pollutants must be integrated with other aspects of soil quality (e.g., biological, physical and other chemical aspects), requiring a holistic soil quality assessment that addresses both. Problems with the often multiple and conflicting functions of soil introduce additional problems, and political pressures from different interested parties.  A further challenge for soil protection policy is to take into account the complexity of environmental situations (e.g., different soil types) within the geographical area covered. We need therefore need highly integrated environmental standards, applied at the catchment scale and similar to those introduced with the EU Water Framework Directive to shift to more sustainable production systems (see: The EU Water Framework Directive: From great expectations to problems with implementation, Science of the Total Environment, 2017, 575, 358-366).


NV: Professor Nick Voulvoulis

Professor of Environmental Technology and Deputy Head of Department, Centre for Environment Policy.

BW: Dr Bonnie Waring

Senior Lecturer, The Grantham Institute for Climate Change and the Environment and the Georgina Mace Centre for the Living Planet

Further information: 


This submission was collated by the Imperial Policy Forum, working in partnership with Imperial College London’s Centre for Environmental Policy, the Grantham Institute for Climate Change and the Environment and the Georgina Mace Centre for the Living Planet. The IPF team supports the policy engagement work of Imperial College London researchers. 


February 2023 


[1] Menegat et al 2022 DOI https://doi.org/10.1038/s41598-022-18773-w

[2] Clark et al. 2020 DOI 10.1126/science.aba7357

[3] https://doi.org/10.5194/soil-5-15-2019

[4] DOI: 10.1038/s41467-019-12622-7