Estimating Soil Compaction Risk at Regional Scales Using Meteorological Data and Soil Spectroscopy

ABSTRACT Soil compaction is a significant form of soil degradation in Europe, reducing agricultural productivity, limiting carbon sequestration and increasing greenhouse gases emissions. In response, the forthcoming European Union Soil Monitoring and Resilience Law requires spatial assessment of topsoil and subsoil compaction risk at district, that is, sub‐national or regional scale. This study applies MIR spectroscopy to develop a novel risk assessment approach for topsoil and subsoil compaction risk (likelihood of becoming compacted) at this required scale, with a spatial resolution of 4 km 2 from 10,000 pits with potential for nationwide application. Topsoil compaction risk was determined using MIR predictions of soil particle size combined with organic matter content and soil drainage classes, while subsoil inherent compaction risk was obtained by combining subsoil texture class with packing density (both obtained by spectroscopy models) and climatic indicators of soil wetness. To have reliable MIR predictions, only representative samples were predicted, and spectral control charts were used to identify unrepresentative samples. By integrating soil meteorological variables, the models were also able to highlight areas where subsoil compaction risk intensifies during wet periods. Such findings are particularly significant on agricultural landscapes where soils frequently reach saturation and remain at field capacity for extended periods. This study illustrates how spectroscopy‐based models offer a fast, cost‐effective, and scalable alternative to fulfil requirements and implementation of Soil Monitoring and Resilience Law. The resulting compaction risk maps can be used by policymakers and regulatory agencies as practical tools to identify high‐risk areas thereby protecting soils into the future.