Developing a practical and relevant soil health measurement toolkit for UK agriculture

Soil physics, chemistry and biology all play a role in productive agricultural and horticultural systems. Interest in soil health by a range of stakeholders (research, policy and practice) has increased. Farmers and growers have taken the initiative to understand the health of their own soils and to develop on-farm approaches to optimise soil biology and health. While physical and chemical properties of soil are relatively well understood, indicator measures for soil biology have been developed only recently. These indicators, however, often have not been produced in parallel with the necessary guidance and tools to allow them to be exploited on farm.

Within a five-year cross-sector programme of research and knowledge exchange (Agricultural and Horticultural Development Board [AHDB] and British Beet Research Organisation [BBRO], Soil Biology and Soil Health Partnership, 2017-2021), we are working with farmers and growers

to maintain and improve the productivity of UK agricultural and horticultural systems, through better understanding of soil biology and soil health. The Partnership will create accessible guidance and tools to help farmers improve soil health. This paper describes some of the initial steps taken, and challenges faced, in the development and testing of a rotational soil health scorecard for routine use on farm. We have compiled a list of

45 of the most relevant biological, physical and chemical indicators for soil health that had been studied. These indicators were then scored, using a logical sieve approach to ensure an objective outcome. The criteria used were considered to be relevant to both agricultural production and environmental impact and practical aspects. We were able to reduce the potential list of indicators to 12 (pH, routine nutrients, loss-on-ignition, microbial biomass, respiration, nematodes/earthworms, visual assessment of soil structure (VESS), bulk density, penetrometer resistance). These will be used in a provisional soil health scorecard during the Programme.

Working with the industry in a Sustainable Agriculture Research and Innovation Club funded project: Developing a UK decision support platform (soilquality.org.uk), we also developed a ‘traffic light’ system to give a visual overview of the status of each indicator, drawing on existing knowledge of threshold values to delineate the categories. So green – amber – red respectively represent low – moderate – high risk of reduced yield and sub-optimal soil conditions. We recommend that the indicator results be benchmarked for comparison over time and within land-use types and pedoclimatic zones. Soil health monitoring from existing medium- and long-term trials, and on-farm, will be used throughout the programme to validate and optimise the scorecard and to evaluate the overall approach.