Blade Aeration Effects on Near‐Surface Permeability and Overland Flow Likelihood on Two Stagnosol Pastures in Cumbria, UK

Overland flow (OF) from permanent pastures is believed to be a rapid pathway to the drainage network and potentially contributes to flooding within numerous grassland regions of the world. Studies investigating whether aeration can reduce observed OF have revealed mixed findings. To improve process interpretation within these studies, topsoil saturated hydraulic conductivity (Kₛ) and penetration resistance (PR) were measured at two permanent Stagnosol (Aquic soil) pastures (P1 and P2) within Cumbria, UK, after blade aeration to 10 cm. Results were measured 2, 6, 13, and 21 wk post‐aeration and compared with the local rainfall record to assess the impact on infiltration excess overland flow (IEOF) likelihood (when rainfall intensity exceeds soil infiltration capacity). Within P1, aeration significantly increased Kₛ by up to a factor of 7.5 and caused several significant reductions in PR between 5 and 15 cm. Aeration decreased the IEOF likelihood during the 13‐ and 21‐wk sampling dates, reducing IEOF likelihood from up to 11.4% of rainfall periods pre‐aeration to 0.0926% of rainfall periods post‐aeration. Aeration within P2 revealed no significant increases in Kₛ, and no PR change besides a significant increase at 10 cm. The IEOF likelihood was virtually identical between aerated and unaerated treatments within P2. The study highlights that aeration can significantly improve Kₛ and PR, as well as substantially reduce the likelihood of IEOF generation, although benefits can be site specific. CORE IDEAS: Aeration can significantly increase topsoil permeability and reduce compaction. Aeration can substantially lower the likelihood of infiltration excess overland flow. Aeration may be ineffective on impermeable subsoils or highly compacted sites. Ex situ permeability results may have limited application within aeration research. Combined BACI and paired‐plot approaches are advised for future aeration studies.