Why is it crucial to understand organic carbon behaviour in UK soils?

Because informed, sustainable management of organic carbon in soils mitigates climate change and secures healthy, productive soils for future generations.

UK-SCAPE Work Package 4: Aims

Holding soil in handsWe aim to better understand the biotic and abiotic controls on the dynamics of soil organic carbon, to determine where UK soil carbon stocks are most at risk of loss, and to identify opportunities to increase soil carbon storage through land management policies and practices.

Soils underpin many important aspects of a functioning society including agriculture, food security, climate change mitigation, flood risk management and urban development. Soil organic carbon (SOC) content is a critical soil property contributing to these functions.

The dynamics of SOC are complex and highly variable depending on geology, climate, vegetation and land-use. Changes in SOC can be gradual in response to chronic pressures (such as climate change) or rapid when acute disturbances occur (for example, land use change and/or pollutant contamination).

There are critical uncertainties in our understanding of SOC dynamics which limit our ability to forecast the likely rate and extent of soil carbon change in response to the complex interacting set of local and global drivers.

“Healthy soils (both urban and rural) are important for food production and human wellbeing. Soil health cannot be measured directly, so indicators (physical, chemical, and biological properties, processes, or characteristics) are generally used. These measurable properties of soil or plants provide clues about how well the soil can function.”

House of Commons Environmental Audit Committee Report on Soil Health 2016-17

Questions

  • What are the critical functional components of the soil biota which affect and are affected by soil structure, and what is their sensitivity to local and global drivers?
  • How can we incorporate these components and into a new model of SOC dynamics?
  • Based on this new understanding, where are there most opportunities to increase SOC and which areas are most at risk of SOC losses?
Soil sampling

Field approach: co-located soil and vegetation studies

The SOC-D field programme is a national scale effort focused on poorly understood processes affecting SOC (such as effective net primary production to soils, below-ground carbon allocation, soil community impacts). The field programme is an open community effort exploiting the unique resources of CEH and external partners and includes:

  • Sites covering all major UK soil-land use combinations:

    • Long-term national soil survey locations with known land use change and soil properties
    • Network of land-use transition sites and long-term experiments
  • Measurements of soil samples to 1m depth:

    • Covering a range of soil biological, physical and chemical measurements
    • Linked vegetation characteristics above and below ground (for example, net primary production and rooting traits)
  • Next generation of experiments and tools:

    • Isotopes, drones and earth observation

Modelling approach - 'living dynamic soil'

Stone wall and fieldsThe SOC-D modelling programme will create a modelling framework that can be used to evaluate SOC models against large-scale monitoring networks and research platforms. The modelling programme uses modular, open-source development, building on existing resources of CEH and external partners to benefit the wider community. Modelling activities will focus on two primary dynamics of SOC:

  • SOC formation and distribution

    • Spatial patterns of plant primary production in the UK
    • Role of plant roots relative to leaf litter in contributing to SOC formation
    • Relative importance of mineral-associated vs particulate processes
  • SOC persistence

    • Dynamic zones of influence from upper plant zone to lower mineral-matrix zone
    • Nationally relevant soil microbial taxa and genes affecting SOC formation and persistence
    • Interactions of soil microbes, animals and mycorrhiza on SOC turnover rates, distribution and feedback on water hydraulic properties

Key innovations

  • A national network of co-located soil and vegetation plots combining biodiversity, physical, chemical and process measurements.
  • A national-scale model of SOC dynamics and national datasets identifying opportunities and risks for UK soils.
  • Community access to datasets and models through the UK-SCAPE data science framework