Evaluation of RUSLE and spatial assessment of agricultural soil erosion in Finland

Agricultural soil erosion has negative effects on surface water quality and aquatic ecosystems. A major impediment to agricultural erosion management in Finland has been the lack of high-resolution country-scale data on the spatial distribution of erosion. As a result, erosion mitigation measures have been targeted with limited information. Therefore, we evaluated the performance of the widely used RUSLE model against measurements from experimental fields, used the model to produce a two-metre resolution crop and management independent erosion estimate for all agricultural lands of Finland, and analysed erosion over different spatial scales. RUSLE showed skill (R2 = 0.76, NSE = 0.72) in estimating the observed erosion at experimental fields (55–2100 kg ha− 1 yr− 1) but with large errors (mean: − 134 kg ha− 1 yr− 1, 90% range: − 711 and 218 kg ha− 1 yr− 1). The evaluation, however, suggests that RUSLE performs similarly in Finland as elsewhere. The analysis of the developed countryscale data, in turn, revealed high erosion regions, and it showed how erosion varies between sub catchment and between and within field parcels. For example, high-erosion areas concentrated in the proximity of water bodies were identified at the sub-catchment and within-field parcel scales. Altogether, the results demonstrate the predictive skill of RUSLE in high-latitude conditions, fill the earlier data gap in country-scale erosion, provide information for targeting erosion mitigation measures, and considerably improve the understanding of the spatial distribution of erosion in Finland.