Can ash control infiltration rate after burning? An example in burned calcareous and gypseous soils in the Ebro Basin (NE Spain)

• Infiltration rate in two contrasting soils (gypseous and calcareous soils) after wildfires.
• Infiltration rate in soils covered with ashes and with no ash.
• The ash increases the infiltration rate in both burned soils.
• The calcareous soils had higher infiltration rates than gypseous soils.
• Calcareous soils covered with ashes produced the greater infiltration rates.

Fire is a long-established ecological factor that has shaped the life history, hydrogeomorphological processes, soil formation and landforms of Mediterranean environments. Soil infiltration is one of the properties affected by fire as a consequence of litter and vegetation removal, and heating of and changes to the biological, chemical and physical soil properties. In this context, ash can play an important role in soil infiltration behavior and therefore affect sediment and runoff yield.The aim of this work is to determine the effect of ash cover on infiltration rates. A single ring infiltrometer was used immediately after a wildfire and before the first storm events to determine the soil infiltration rate. A total of 24 infiltrations were made (2 soil types × 2 treatments × 6 replicates). In each infiltration experiment, the soil wetting front, the bulk density and stoniness were also measured. The results show that the final infiltration rate (fc) values are higher in calcareous soils than in gypseous soils. The ash cover in calcareous burned soils only temporarily decreases the bulk density of topsoil and enhances infiltration.

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