Effects of prescribed fire on topsoil properties: a small-scale straw burning experiment

A grassland was burned to investigate how a short prescribed fire affected soil physical and hydraulic properties, soil water balance, and emergent vegetation. Three years before the experiment at Řisuty, Czech Republic, the grassland was re-established on arable soil. At the experimental site there is a weather station and sensors measuring soil temperature and moisture at three different depths. The 5 m × 5 m burned plot was compared to a nearby unburned reference location. The loamy Cambisol soil was not water-repellent. 250 m² of sun-dried grass was raked and burned at the burned plot. The fire lasted approximately 15-minute and reached 700 °C. Soil samples were taken immediately after the fire and weekly to monthly thereafter to quantify organic carbon content, soil structure stability, hydraulic conductivity, bulk density, and texture. According to the research results, it appears that temporary burning improved the hydraulic properties of the topsoil. The fire plot’s infiltration capacity was increased, and soil water content was higher than the control plot throughout the year, providing suitable habitat for colonizing vegetation. The results suggest that small-scale controlled biomass burning can be risk-free to the soil ecosystem and may even temporarily improve the hydraulic properties of the upper soil layer.