Mapping topsoil behavior to compation at national scale from an analysis of field observations

Authors: RICJER-DE-FORGES, ANNE - Inrae; ARROUAYS, DOMINIQUE - Inrae; CHEN, SONGCHAO - Zhejiang Sci-Tech University; Libohova, Zamir; BEAUDETTE, DYLAN - Natural Resources Conservation Service (NRCS, USDA); BOURENNANE, HOCINE - Inrae

Submitted to: Land
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2024
Publication Date: 7/8/2024
Citation: Ricjer-De-Forges, A.C., Arrouays, D., Chen, S., Libohova, Z., Beaudette, D.E., Bourennane, H. 2024. Mapping topsoil behavior to compation at national scale from an analysis of field observations. Land. https://doi.org/10.3390/land13071014.
DOI: https://doi.org/10.3390/land13071014

Interpretive Summary: Soil compaction affects water movement, soil health and many agricultural practices. Measuring of soil compactness is limited to small areas and field observations made by surveyors and farmers. Combining field observations of soil compactness with other laboratory analysis and soil maps can be useful to map the soil behavior and response to compaction. In this study, we identified six classes of soil compactness degree from field and laboratory data to asses soil behavior to compactness and mapped soil response to compactness. The maps of soil compactness and soil response to compactness will be a valuable tool for regional planning of machinery type and land management practices while helping farmers manage field traffic and avoid soil degradation and excessive runoff of fertilizers and pesticides at field scale.

Technical Abstract: Soil compaction is one of the most important and readily mitigated threats to soil health. Digital Soil Mapping (DSM) has emerged as an efficient method to provide broad-scale maps by combining soil information with environmental covariates. Until now, soil information input to DSM has been mainly composed of point-based quantitative measurements of soil properties and/or of soil type/horizon classes derived from laboratory analysis, point observations, or soil maps. In this study, we used field estimates of soil compaction to map soil behavior to compaction at a national scale. The results from a previous study enabled clustering of six different behaviors using the in situ field observations. Mapping potential responses to soil compaction is an effective land management tool for preventing future compaction. Random forest was used to make spatial predictions of soil behavior to compaction over cultivated soils of mainland France (about 210,000 km2). Modeling was performed at 90 m resolution. The map enabled us to spatially identify clusters of possible responses to compaction. Most clusters were consistent with known geographic distributions of some soil types and properties. This consistency was checked by comparing maps with both national and local-scale external sources of soil information. The best spatial predictors were available digital maps of soil properties (clay, silt, sand, organic carbon (SOC) content, and pH), some indicators of soil structural quality using SOC and clay content, and environmental covariates (T °C and relief-related covariates). Predicted maps were interpretable to support management recommendations to mitigate soil compactness at the soil–scape scale. Simple observational field data that are usually collected by soil surveyors, then stored and available in soil databases, provide valuable input data for digital mapping of soil behavior to compaction and assessment of inherent soil sensitivity to compaction.