A Comment on “Empirical modelling of soil erosion using unit plot data at Sparacia experimental area (southern Italy)”

Abstract Purpose To comment on the results presented by Pampalone et al. J Soils Sediments 24(6) 2535-47, Pampalone et al., J Soils Sediments 24:2535–47, 2024 on the effects of slope length and gradient on average annual soil losses over 5 years at the Sparacia experimental area in southern Italy. Methods Analysis of erosion data presented by Pampalone et al J Soils Sediments 24(6) 2535-47, Pampalone et al., J Soils Sediments 24:2535–47, 2024 in respect to the relationships between soil loss per unit EI 30 and slope length and gradient. Results The relationships between soil loss per unit EI 30 and slope length and gradient for the experiments reported by Pampalone et al. J Soils Sediments 24(6) 2535-47, Pampalone et al., J Soils Sediments 24:2535–47, 2024 differ appreciably from those used by the RUSLE. Contrary to assumptions underpinning USLE-based models, runoff ratios at Sparacia vary with slope length and gradient. Conclusions Variations in runoff ratios with slope length and gradient cause discrepancies between the effects of topography at Sparacia and equations normally used to account for the effects of topography in USLE-based models. The number of erosion events reported by Pampalone et al. J Soils Sediments 24(6) 2535-47, Pampalone et al., J Soils Sediments 24:2535–47, 2024 may not be sufficient to make definitive conclusions on how erosion varies with slope length and gradient in the long term that USLE based technology focuses upon. In addition, sedimentation during the sampling procedure adopted to determine the bulk sediment concentration for erosion events at the Sparacia experimental site may have affected the veracity of the measured soil losses.