Long-term organic fertilisation shifts N2O production towards denitrification in an alpine grassland soil

作者：Johannes Friedl, Carlos Claramonte Manrique, Kathiravan Meeran, Andreas Bohner, Robert Kirkby, Sebastian Wieser, Martin Gerzabek, Katharina Keiblinger · 年份：2026 · DOI：10.5194/egusphere-egu26-11221 · 研究领域：Soil Carbon and Nitrogen Dynamics、Soil and Water Nutrient Dynamics、Plant nutrient uptake and metabolism

Organic fertilisers including farmyard and liquid manure supply organic matter and nutrients to grassland soils, with potential benefits for organic carbon (C) storage, soil fertility and ultimately, productivity. However, these benefits may be partially offset by changes in nitrogen (N) turnover and associated emissions of nitrous oxide (N₂O), a potent greenhouse gas, contributing to climate change. Here, we investigated legacy effects of long-term fertilisation on N transformations and N₂O production pathways from an alpine grassland soil from Styria, Austria, subjected to organic (ORG), mineral (NPK), or no fertilization (NIL) since 1971. Combining the 15N pool dilution and the 15N gas flux method enabled to quantify gross rates of mineralisation, nitrification, and dissimilatory nitrate reduction to ammonium (DNRA), together with N2O production pathways and the reduction to environmentally benign dinitrogen (N2) in a soil microcosm experiment. Long-term organic fertilisation increased soil organic C and CO2 emissions compared to NPK and NIL, consistent with increased rates of mineralisation, nitrification, and increased N retention via DNRA. Under the conditions of the experiment, long-term fertilisation showed no effect on magnitude of N2O and N2 emissions. Denitrification was the main pathway of N2O production across treatments, with its contribution increasing from 65% under NIL and NPK, to >85% under ORG. The main product of denitrification was N2, accounting for 9...