Developing novel soil health indicators using lipidomic and metabolomic analyses across key land use types

Healthy soils are essential in achieving climate neutrality, reversing biodiversity loss, providing nutritious food, and safeguarding human health. Despite decades of soil research, soil remains a highly threatened non-renewable resource, with an estimated 62% of EU soils already degraded. This is attributed to the complexity of soil as a material and ecosystem, the diversity of soil types and land uses and to a large extent, the global focus on soil as an agricultural resource rather than as an essential part of environmental protection. The EPA funded project Microbial and Metabolite-based indicators for Soil Health (MMeSH) aims to address the need for biological soil health indicators and environmental protection of soils by using a combined lipidomics, metabolomics, and genomics approach. Advanced mass spectrometry- and nuclear magnetic resonance-based techniques will be used to profile the soil lipidomes from soil organisms. Soils (n=219) were sampled from September 2023 to April 2024 from existing Geological Survey Ireland (GSI) Tellus sites. Sample sites represented key land uses and soil types in Ireland: 51% corresponded to pastures, 13% to agricultural land with natural vegetation, and 12% to peat bogs (based on CORINE Land Cover categories). Peat soils (21%) were the major soil type, followed by luvisols (18%), brown Earths (17%) and surface-water gleys (12%) (based on the Irish Soil Information System database). Lipid extraction and analysis by both gas and liquid chromatography mass spectrometry is ongoing. Phospholipid fatty acids as well as intact polar lipids will be used to identify taxonomic and phenotype changes within the soil microbiome. This coupled with untargeted metabolomics and the identification of other secondary metabolites will aid in the understanding and the development of novel soil health indicators for each unique soil system.