Main content area

Reduction of nutrient losses with eroded sediments by post-fire soil stabilisation techniques

Gómez-Rey, M. X., Couto-Vázquez, A., García-Marco, S., Vega, J. A., González-Prieto, S. J.
International journal of wildland fire 2013 v.22 no.5 pp. 696-706
burnt soils, cations, fires, grasses, nitrogen content, nutrient availability, nutrient content, nutrients, physicochemical properties, plant litter, sediments, seed treatment, shrublands, soil stabilization, sowing, straw mulches, Spain
After an experimental fire in steep shrubland in a temperate–humid region (north-west Spain), the effects of two post-fire stabilisation treatments (grass seeding and straw mulching) on the chemical properties of eroded sediments, and the amount of nutrients lost with them, were evaluated relative to control burnt soil, over a period of 13 months. Total C and N concentrations, and δ13C, indicated that sediments were mainly contributed by charred plant and litter material. The highest concentrations of extractable base cations in the sediments occurred during the first 3 months following fire, especially for Na and K. As treatments had little or no effect on nutrient concentration in sediments, differences in nutrient losses were due to the 10-fold lower sediment production in mulching compared with other treatments. In control and seeding treatments, the accumulated amounts of nutrients lost with sediments were 989–1028kgha-1 (C), 77kgha-1 (N), 1.9–2.4kgha-1 (Ca), 0.9–1.1kgha-1 (Mg), 0.48–0.55kgha-1 (NH4+–N), 0.39–0.56kgha-1 (K), 0.19–0.34kgha-1 (Na) and <0.1kgha-1 (P and NO3-–N). These values accounted for 22–25% (total C and N) and 5–12% (NH4+–N, Ca, P and Mg) of available nutrients in ash, and 1.0–2.4% of those in ash+topsoil. As nutrient and sediment losses were strongly correlated, the reduction of the latter by mulching application leads to an effective decrease of post-fire nutrient losses.