P and K additions enhance canopy N retention and accelerate the associated leaching

Chiwa, Masaaki; Sheppard, Lucy J.; Leith, Ian D.; Leeson, Sarah R.; Tang, Y. Sim; Cape, J. Neil. 2019 P and K additions enhance canopy N retention and accelerate the associated leaching. Biogeochemistry, 142 (3). 413-423.

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This study evaluated the interactive effects of combined phosphorus (P) and potassium (K) additions on canopy nitrogen (N) retention (CNR) and subsequent canopy leaching at a long-term N manipulation site on Whim bog in south Scotland. Ambient deposition is 8 kg N ha-1 year-1 and an additional 8, 24, and 56 kg N ha-1 year-1 of either ammonium (NH4+) or nitrate (NO3-) with or without P and K has been applied over 11 years. Throughfall N deposition below Calluna vulgaris and foliar N and P concentrations were assessed. Results showed that 60% for low dose and 53% for high dose of NO3- contrasting with 80% for low dose and 38% for high dose of NH4+ onto Calluna was retained by Calluna canopy. The CNR was enhanced by P and K addition in which 84% of NO3 - and 83% of NH4+ for high dose were retained. CNR for NO3- increased the canopy leaching of dissolved organic N (DON) and associated organic anions. NH4+ retention increased canopy leaching of magnesium and calcium through ion exchange. Even over 11-years N exposure without P and K, foliage 29 N:P ratio of Calluna did not increase, suggesting that N exposure did not lead to N saturation of Calluna at Whim bog. Our study concluded that increases in P and K availability enhance CNR of Calluna, but accelerate the associated canopy leaching of DON and base cations, depending on foliar N status.

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Atmospheric Chemistry and Effects (Science Area 2017-)
UKCEH Fellows
ISSN: 0168-2563
Additional Information. Not used in RCUK Gateway to Research.: Publisher link (see Related URLs) provides a read-only full-text copy of the published paper.
Additional Keywords: manipulation experiment, peatland, Calluna vulgaris, dissolved organic nitrogen, base cations, long-term study
NORA Subject Terms: Ecology and Environment
Related URLs:
Date made live: 30 Jan 2019 12:17 +0 (UTC)

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