Rapid immobilisation and leaching of wet-deposited nitrate in upland organic soils

Evans, Chris D. and Norris, Dave and Ostle, Nick and Grant, Helen and Rowe, Edwin C. and Curtis, Chris J. and Reynolds, Brian (2008) Rapid immobilisation and leaching of wet-deposited nitrate in upland organic soils. Environmental Pollution, 156 (3). pp. 636-643. ISSN 0269-7491

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Nitrate (NO3-) is often observed in surface waters draining terrestrial ecosystems that remain strongly nitrogen (N) limited. It has been suggested that this occurs due to hydrological bypassing of soil or vegetation N retention, particularly during high flows. To test this hypothesis, artificial rain events were applied to 12 replicate soil blocks on a Welsh podzolic acid grassland hillslope, labelled with 15N-enriched NO3- and a conservative bromide (Br-) tracer. On average, 31% of tracer-labelled water was recovered within 4 h, mostly as mineral horizon lateral flow, indicating rapid vertical water transfer through the organic horizon via preferential flowpaths. However, on average only 6% of 15N-labelled NO3- was recovered. Around 80% of added NO3- was thus rapidly immobilised, probably by microbial communities present on the surfaces of preferential flowpaths. Transitory exceedance of microbial N-uptake capacity during periods of high water and N flux may therefore provide a mechanism for NO3- leaching.

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Journal Article
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Environmental Pollution
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30 Nov 2018 08:40
Last Modified:
22 Nov 2022 06:44