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Soil management

Work Package Soil

Research Deliverable 
Soil management

Introduction

Soils provide a range of benefits for society including growing crops and timber, regulating water flow, and storing carbon. However, these functions face threats from soil erosion, compaction, contamination, and losses to urban expansion. It is therefore vital that soils are managed sustainably to ensure that future generations have healthy soils that can provide these functions that are demanded by society and ensure our food security into the future.

Providing tools to enable land managers to sustainably manage soils, reduce degradation of the soil resource and minimise the impact on other parts of the environment can help to protect and enhance soil quality. These tools can range from rapid methods to assess changes in soil quality to providing guidance on which soils are susceptible to erosion or compaction.

The UN sustainable Development goals, the National Performance Framework, the Land Use Strategy and Scottish Soil Framework (and others) all give an overarching context to the current research.

Aim of Research

To support the sustainable use and management of Scotland’s soil resource. We will provide new and improved tools to predict how soil functions respond to land use, management and environmental pressures. These decision support tools will enable users to address a wide range of policies and decision-making across scales from field to national to help improve the management of our natural assets to support sustainable land-based industries, increase the land under sustainable soil management and restore degraded soils to enhance and safeguard the multi-functional capacity of Scotland’s soils under a changing climate and other drivers of change.

Progress

2021 / 2022
2021 / 2022

A detailed soil sampling campaign was undertaken at the Glensaugh Research Farm to establish a baseline of soil carbon stocks from which change can be measured as the farm transitions to become net-zero or climate positive. Around 100 profile pits were excavated and each of the major mineral and organic horizons were sampled to determine soil carbon stocks. It is estimated that the Farm holds around 240,000 t C within the upper 1m of soil. Allied to the determination of soil C stocks, each of the samples were used to develop a FTIR spectral dataset from both fresh and dried soils. This dataset will be used to develop calibrations between soil carbon and spectra to further develop more field-based applications for FTIR analysis and soil monitoring using handheld FTIR instruments. A limited set of soil physical properties (particle size, water retention and aggregate stability) were measured on additional samples taken from the more intensive grassland sites on the farm and will form part of datasets to be used in developing soil health indicators in the new 2022-27 Strategic Research Programme.

A series of conceptual models of dominant water flow pathways through soil and substrate were developed to characterise soil hydrology of both hillslope and adjacent floodplains that can be related to pollution pathways and, in turn, to the suitability of pollution mitigation measures. The models comprised of hillslope sub-models linked to floodplain settings that reflected gradients of inherent soil drainage and subsequent soil wetness regimes and considered the presence of artificial drainage systems. In collaboration with a related project in RD 1.1.2, we explored how these riparian context models can be used in practise at the farm to field scale to guide the targeted selection of management measures that intercept and retain water and pollution taking account of differences in surface and subsurface pathways. These measures include conventional and novel buffer strips and in-channel management options.

We engaged with stakeholders in the supply part of the growing media value chain and conducted 9 interviews covering different perspectives and interests. The peat-based and peat-free growing media supply chains are closely linked and the need for change and adopt to a peat-free production was commonly agreed by the different stakeholders in the industry. However, several common challenges such as the availability, quality, and consistency of alternative materials at reasonable cost and in sufficient volumes regularly came up in conversations and are identified as the reasons for delay and reluctance for actual change in the market. Addressing these structural barriers will add to the impact of any policy change such as retail ban of peat based growing media and taxation of bag content for peat.

We updated data and calculation of costs of peatland restoration using data collected as part of the grant application and reporting process for the Peatland Action Programme (PAP) in Scotland. The database includes information from 142 unique projects covering 323 restoration sites in Scotland, of which data from 300 sites were suitable for the analysis. Based on more reliable final grant report data, our revised estimate of restoration cost per hectare is £1712 (median: £1026). Restoration costs are twice as high in the presence of forest-to-bog restoration relative to the absence of such activities.

Highlights:

  • Baseline soils data for Glensaugh Climate Positive Farming Initiative: The first systematic soil profile collection covering all of James Hutton Institute Glensaugh Research Farm has been completed, with over 100 soil profiles described and sampled. Samples taken from each soil layer will be used to set a baseline for soil carbon stocks to monitor changes as the farm transitions under the Glensaugh Climate Positive Farming Initiative.
  • A unique FTIR spectral dataset for Glensaugh Farm: FTIR spectra have been recorded of both dried milled soils and fresh soils from each of the 100 sites sampled (as described above). This unique dataset will allow development of calibrations to predict soil organic carbon on a farm scale and the development of more field-based applications for FTIR analysis and monitoring using the handheld FTIR.
  • Report on landscape typing to target riparian management options: A report was prepared that utilised a series of hillslope and adjacent floodplain soil hydrology models to better target measures to reduce diffuse pollution in rivers and streams. A total of 16 management options to mitigate runoff were detailed. The models were applied to two catchments in north-east Scotland to determine how the methods inform farm level to catchment screening of how landscape variation dictates groups of mitigation measures as more to less suited. DOI:10.5281/zenodo.6414406.
  • We identify that increasing uptake of alternatives to peat in horticulture will require addressing technical and economic challenges, as well as social acceptance, and that the one of the largest bottlenecks is likely to be availability of reliable, peat-free alternatives. Two reports were produced, which have been actively sought by Scottish Government, research results have been shared in requested meetings with government scientists.
  • Significant benefits to society of early action on peatland restoration. Study finds that restoring Scotland’s peatlands by 2027 rather than between 2039 and 2050 would provide an additional £191 million in societal benefits for the country. The study, published in the journal Global Environmental Change, adds to the economic rationale for early investments into nature based solutions.
2020 / 2021
2020 / 2021

We have developed computer-based models, maps, smartphone apps and sensing techniques to help sustainably manage Scottish soils while also protecting the aquatic environment. We used Digital Soil Mapping (DSM) techniques to improve the resolution of an existing national scale soil hydrology map. The new map has a resolution of 50m grid cells and helps to disaggregate the compound map units on the national soil map of Scotland. Comparison between the disaggregated map and conventional detailed mapping showed a measurable improvement in accuracy when predicting baseflow index.

The work on identifying areas at risk of soil erosion (estimated to cost around £50M and a loss of 920,000 t of soil annually) has continued with improvements to the area covered by erosion risk maps, development of a smartphone app that allows users to record and upload instances of soil erosion and the development of a tool that allows a user to investigate the impact of changes in land management on erosion risk. The smartphone app is available for Android and Apple mobile devices and as a website at http://soilerosion.hutton.ac.uk/.

Progress has been made in developing spectroscopic analytical methods for soil monitoring using advanced statistics to improve predictions of soil parameters from combined infrared spectroscopy and x-ray fluorescence. These non-destructive measurement methods can provide rapid quantification of a wide range of soil chemical and physical properties and offer significant progress towards screening soils for changes in soil properties or detecting nutrients and contaminants.

Peatlands store vast amounts of soil carbon but are vulnerable to releasing this carbon in the form of the greenhouse gas, CO2. Peatland restoration is a way to prevent this loss and our research has found considerable benefits for early restoration action (up to £110 million annually across Scotland), linked to an increased resilience of peatlands under future climate change. This contrasts with the cost of peatland restoration with average restoration costs per hectare estimated at £1900, with a median of £1000. In line with previous research, these costs depend on restoration activity and initial condition of the peatland with restoration cost per hectare being approximately twice as high in forest-to-bog restoration relative to other activities, and greater in eroded sites. A key step in maintaining peatlands is to replace peat as a growing medium in gardens with non-peat products. Our research shows that availability, pricing, performance, standardization and familiarisation of these non-peat products were key to acceptance by gardeners as a growing medium.

Highlights:

  • It is estimated that 920,000 t of soil is lost through erosion annually in Scotland, enough to fill Murrayfield stadium. As there are no systematic measurements of the extent or severity of soil erosion in Scotland, we have developed a soil erosion reporting app for both Android and Apple smartphones and a related website where records and photographs of erosion can be uploaded. We can use this information to help validate our soil erosion risk maps and help land managers to more sustainably manage the soil resource.
  • Research on technical and viable options for soil carbon sequestration, of key importance as a potential means of climate change mitigation, is dependent on the availability of tools and methods to monitor soil carbon changes through time. Spectroscopy has the potential to give accurate predictions of many soil parameters from a single scan of a soil sample, and therefore provide a time saving and cost-effective means of soil monitoring. Through the use of ATR-FTIR spectra and advanced statistical methods we have achieved significant improvements in the accuracy of spectroscopic predictions of soil organic carbon (SOC).
2019 / 2020
2019 / 2020

Sustainable soil management requires that we maintain the multiple functions of the soils. To help achieve this, we have developed and enhanced tools to manage soils at a range of scales to prevent soil loss and protect the aquatic environment, while maintaining key soil functions. These tools include a series of computer-based models and maps to help policy-makers and land managers to manage the land. The maps can be used to inform land managers on which soils are most susceptible to damage and where the risk of run-off and erosion is greatest, thus helping to reduce damage to the soil and to limit diffuse pollution in rivers and streams while retaining the key functions of the soil such as production of food. We have also updated maps of soil wetness, a key factor in limiting agricultural production, by updating the climate data used to generate the maps to reflect Scotland’s changing climate.   The computer models can be used to determine the impacts of climate change and land use on soil organic matter, crop production, leaching and erosion. Along with maps and models, we are developing methods to assess the impact of land use and climate change using novel, rapid sensing techniques such as portable X-ray fluorescence and infra-red spectroscopy to quantify changes in soil properties through time and to provide early warnings of deleterious changes and have developed a mobile phone app to allow citizen’s to record soil erosion and provide us with additional data to validate our models. Our work on assessing how monetary and non-monetary values influence land managers' decisions around sustainable soil management has progressed. A key focus of this work is in quantifying the financial costs of peatland restoration and the financial cost to the environment caused by soil erosion. However, it was also found that the perceptions of the public and land managers are also important in developing policy instruments to improve and maintain sustainable soil use.

Highlights:

  • Caring for ‘Cinderella’ – perceptions and experiences of peatland restoration in Scotland. Researchers explored why people involved in the use, conservation and restoration of peatlands care about peatbogs. Results highlight the importance of personal experiences, relationships and embodied learning. They also show that a lack of knowledge can be a barrier to good care, but acknowledging uncertainty and a lack of knowledge can allow for inclusion of other knowledge and the co-creation of knowledge and caring practices. For this to happen, appropriate structures (e.g. flexible peatland restoration funding) and open and inclusive attitudes are needed.
  • Reducing soil erosion through prediction of erosion vulnerability: We have produced soil erosion risk maps that identify areas of land most susceptible to erosion by water to help land managers adjust cultivations to reduce the impacts of erosion such as sediment and nutrients entering our rivers and streams. The maps (available on Scotland’s Soils website) show how soils and landform combine to increase the likelihood that runoff from saturated soils will cause erosion resulting in the loss of valuable topsoil, nutrients and carbon.
  • Soil carbon content remains stable in some agricultural soils in Scotland: Research to measure  change in soil carbon (C) concentration, soil pH and major nutrients of 37 topsoils from a number of on-farm experimental sites that ran from the from 1950s to 1980s in north-east Scotland has indicated no significant change in soil C concentration, despite coinciding with increased agricultural intensification. The sites were resampled in the autumn of 2017 with an average of 54 years between sampling. However, measuring soil carbon concentration alone is a poor indicator of changes over time as demonstrated by the National Soil Inventory of Scotland resampling which showed a statistically significant decrease in C concentration, but no change in stocks when topsoil thickness and bulk density were also taken into account. Measures of concentration alone should only be used as an ‘early warning’ of potential change.
2018 / 2019
2018 / 2019

Sustainable soil management requires that we maintain the multiple functions of the soils. We have developed a series of maps, models and methods that allow us to investigate how soils will respond to pressures from land use and climate change from field to national scale while retaining those multiple functions such as water supply for growing crops, carbon storage and sequestration.  The maps can be used to examine how changes in land use, for example agricultural or forestry expansion, will alter the ability of the soil to perform a range of functions. In particular, these maps also allow an assessment of the probablility of the soil being able to provide a range of functions. National scale mapping of soil water availability provides key input data for running crop production models and parts of this work have been incorporated into the SoilMAT suite of simple models which can be used to investigate changes in soil properties such as carbon sequestration with land use or climate changes. We have identified costs and public preferences related to peatland restoration, a key aspect in climate change mitigation and modelled the long-term changes in soil functions of grasslands in response to changes in soil pH.

Highlights:

  • Soil carbon research: SEFARI scientists presented an overview of work on soil carbon sequestration in relation to land use at a workshop on UK Soil Organic Carbon Data and Modelling at the Centre for Ecology and Hydrology in Lancaster. The aim of the workshop was to identify dataset to help in the development and validation of new models of soil carbon dynamics. Previous research on the potential for carbon storage in Scotland's agricultural soils was presented at Climate Week 2018 in Victoria Quay, Edinburgh and an article on the potential to pay farmers to sequester and store carbon in their soils and the beneficial effect of increasing soil carbon on water retention, on increased resilience to erosion and on soil biodiversity was published in the Scotsman on World Soil Day (5th December).  
  • Policy interaction: Using digital mapping resources for soil hydrological data (developed in the SRP through interaction with CREW and Underpinning Capacity), SEFARI researchers were able to provide evidence to the Scottish Government (Climate Change and Business Support) in support of a derogation request to the European Commission. The evidence on the impact of the wet 2018 spring on soil wetness, and the potential damage that would result from farmers being forced to cultivate saturated soils to comply with Crop Diversification regulations under the EU CAP Greening, was used to support a successful application to the European Commission that prevented thousands of farmers across Scotland facing penalties for breaching an EU regulation.
  • Knowledge accounts: Information generated (publications and reports) by SEFARI researchers on economic and social aspects of peatland restoration options contributed to Scottish government-produced knowledge accounts of Scotland’s natural assets. This information highlighting the importance of peatlands in the provision of ecosystem services and the potential risks and knowledge gaps in relation to public and land-manager acceptance of potential peatland restoration options. This information was also used in an application for funding to investigate barriers to uptake of peatland restoration management, led by the Soil Association.
2017 / 2018
2017 / 2018

Reliable spatially explicit information about soil is important for modelling soil functions and the benefits these bring to society. Digital soil mapping techniques were used to derive estimates of soil physical, chemical and hydrological properties that were then used to produce national scale maps of a range of soil functions and threats to the soil resource. These included risk and function models to estimate compaction, erosion risk, greenhouse gas (GHG), water and nutrient regulation. The maps and datasets can be used to explore scenarios of land use and climate change as well as providing a framework for sustainably managing the soil resource. The integration of spectroscopic and remote sensing (satellite) data is being explored to assess the condition of Scottish peatlands and supports the work to enhance  understanding  of restoration  costs  and  their  variation  across  measures,  peatland  condition,  and  location  of restoration sites.  

Highlights:

  • Valuing peatland restoration benefits: A paper has been published that shows that environmental attitudes and a sense of place positively contributes to the monetary value that people attach to peatland restoration.  Further qualitative work on the role of people (sense of care, responsibility and connection) in relation to perceptions of rewilding of peatlands has been highlighted at a number of conferences. The work has shown that peatland restoration is likely to generate net benefits for society which will help in persuading land managers the value of peatland restoration. Quantitative work, in collaboration with Leeds University, has summarised existing evidence on cost-effectiveness of peat restoration options, and produced recommendations for future collection and analysis of economic data (Report). Key findings and recommendations from both qualitative and quantitative work have been presented to the National Peatland Group.
  • Raising the global profile of SEFARI soils work: Major contributions were made to the international Pedometrics conference (which was attended by over 200 delegates from across the world) by SEFARI staff through oral and poster presentations, running training workshops, and giving keynote talks. Two papers based on previous RESAS funded work were selected for a special virtual journal 25th anniversary issue.
  • Digital tools:  SoilMAT is a simple summary process-based model, which has been initially developed in MS Excel. The model has modules to predict soil texture, carbon storage and water supply to describe the impact of changes in temperature and rainfall on crop production and to determine fertiliser use, nutrient limitation, nitrate leaching and greenhouse gas emissions in Scottish soil.  Meetings with stakeholders help to ensure an alignment between land use scenarios of importance to them and SoilMat development. Evaluation and validation of the modules will take place over the coming years. (EGU2018-12925 | Presentation).
  • Soils Risk Maps: A series of risk maps for much of the cultivated land in Scotland have been developed to help farmers identify areas vulnerable to erosion, compaction, leaching and runoff. These maps integrate work funded by CREW, Underpinning Capacity and the SRP, and are aimed at improving water quality by reducing diffuse pollution from land-based activities. SEPA, Scottish Water and SNH have asked to be provided with these maps and they will also be accessible via Scotland’s Soils website for use by land managers.
2016 / 2017
2016 / 2017

Having reliable spatially explicit information about soil is important to modelling a wide range of soil functions and their response to external pressures. Soil texture is specifically important as it influences several key properties and processes. A 3D model of soil texture has been produced using digital soil mapping techniques.  The results can be used as input for further soil functions modelling in the context of ecosystem services provision.

We have also developed a framework to model changes in soil processes due to changes in soil pH. The addition of lime to agricultural soils to improve crop growth also impacts on other soil functions and processes. We have reviewed a range of soil models used to predict these changes that will be used in subsequent years to envaluate the impact of changing pH on soil functions.

Scotland’s peat soils are seen as a significant carbon store but, to date, there has been a lack of systematic Scotland-wide data on peat depths. A review of litrature was undertaken in order to derive a dataset of peat depths that can be used to quantify carbon stocks in Scottish soils.

Highlights:

  • A new soils website is now operational where there is a wide range of soil information and where various datasets can be downloaded making Scottish soils data much more accessible.
  • The Soil Monitoring Action Plan (SoilMAP) has underpinned new activities in monitoring soil erosion through engagement with Scottish Environmental Protection Agency (SEPA), Scottish Water, CREW and through citizen science. The data gained will inform the risk-based modelling of soil erosion.
  • A web-based Peatland Condition Assessment support tool and a Peatland Learning Module have been developed in collaboration with Leeds University.
  • A paper on public perceptions of peatlands was published, based on a focus group study. The main finding was that often the same people have ambivalent views of peatland as both good and bad, similar to nature/wildernesses and cultural landscapes under human management. Understanding of what people value and see as important needs to be taken into account in communication and planning.
  • 48 tweets were made over a 24-hour period to mark World Soil Day (5th Dec 2016) reaching nearly 6000 followers.

 

Future Activities

The work in riparian context models will be used in the D2-2 AiM NBS project (2022-27 Strategic Research Programme) to inform the development of functional river corridor units, described in terms of key inherent variables of soil water, soil and vegetation C stocks, which will be used to assess the role of river corridors and their management in climate change resilience. It will also inform the development of riparian landscape units that group nutrient processes and dynamics in the land-water interface in the context of a NERC-funded project.

Soil data collected from the Glensaugh Research farm will be used in the 2022-27 Strategic Research Programme project on soil Health (D3-1, Healthy Soils for a Green Recovery) to help develop soil health indicators and to further develop the application of hand-held FTIR spectroscopy in the field.

Selected Outputs

2016/17

2017/18

2018/19

2019/20

2020/21

2021/22

  • We have developed a dataset of soil morphological and site characteristics, soil C concentrations, bulk density, horizon thickness, soil c stocks and spectral data for over 100 locations on the Glensaugh Research farm on a 400 and 200m grid.
  • We have completed the final project report on the demand side of the growing media supply chain combining the available responses we had by mid-March 2022 with the available literature. This output aimed to understand the needs of the gardening and horticulture supply chain and the reasons for their dependence on peat. Our focus was not only limited to peat-free compost producers and retailers but also other direct and indirect players in the supply chain such as councils as collectors of organic waste, recycling companies as producers of compost and anaerobic digestate, peat extractors, NGOs, policy makers and as well as producers and retailers that deal with both peat-based and peat-free products.
  • A report was produced in collaboration with RD 1.1.2 presenting concepts and methods for developing the riparian context models and demonstrating their application at field scale for short-listing riparian management measure options for effective diffuse pollution mitigation:  Stutter, M., Gagkas, Z. and Lilly, A., 2022. Landscape typing based on hillslope and floodplain soil water models to functionally target sixteen riparian management options. James Hutton Institute, Aberdeen. DOI:10.5281/zenodo.6414406.
  • A report on the costs of peatland restoration was written which provides an update on an earlier report and using data collected as part of the grant application for the Peatland Action Programme. Additionally, work on the impact of how questions were phased on the willingness-to-pay for environmental benefits was published in Land Economics.
  • Work exploring the economic implications of delaying GHG mitigation through ecosystem (peatland) restoration used a large survey (N = 1377) that included a choice experiment to elicit the public’s willingness to pay (WTP) for peatland restoration found that early action produced considerable financial benefits (up to £191 million annually).
  • A process-based model, DigiBog, was used to simulate the effects of land use on blanket peatlands, which were related to estimates of changes to the public’s well-being derived from peatland degradation and restoration as monetary values. By quantifying the linkages between environmental conditions and social values, the translation between these system components becomes more transparent and allows value estimates to be recalculated under different ecological scenarios, or as new evidence emerges.

Research Deliverable Lead

Dr Allan Lilly

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