Reduction of Nutrient Losses with Eroded Sediments by Post-Fire Soil Stabilisation Techniques

摘要

After an experimental fire in steep shrub land in a temperate–humid region (north-west Spain), the effects ofudtwo post-fire stabilisation treatments (grass seeding and straw mulching) on the chemical properties of eroded sediments,and the amount of nutrients lost with them, we reevaluated relative to control burnt soil, over a period of 13 months. Total Cudand N concentrations, anduddud13udC, indicated that sediments were mainly contributed by charred plant and litter material. Theudhighest concentrations of extractable base cations in the sediments occurred during the first 3 months following fire,udespecially for Na and K. As treatments had little or no effect on nutrient concentration in sediments, differences in nutrientudlosses were due to the 10-fold lower sediment production in mulching compared with other treatments. In control andudseeding treatments, the accumulated amounts of nutrients lost with sediments were 989–1028kghaud1ud(C), 77kghaud1ud(N),ud1.9–2.4kghaud1ud(Ca), 0.9–1.1kghaud1ud(Mg), 0.48–0.55kghaud1ud(NHud4udþud–N), 0.39–0.56kghaud1ud(K), 0.19–0.34kghaud1ud(Na)udandud,ud0.1kghaud1ud(P and NOud3ud–N)ud.udThese values accounted for 22–25% (total C and N) and 5–12% (NHud4udþud–N, Ca, P andudMg) of available nutrients in ash, and 1.0–2.4% of those in ashudþudtopsoil. As nutrient and sediment losses were stronglyudcorrelated, the reduction of the latter by mulching application leads to an effective decrease of post-fire nutrient losses.