Modelling nitrogen saturation and carbon accumulation in heathland soils under elevated nitrogen deposition

A simple model of nitrogen (N) saturation, based on an extension of the biogeochemical model MAGIC, has been tested at two long-running heathland N manipulation experiments. The model simulates N immobilisation as a function of organic soil C/N ratio, but permits a proportion of immobilised N to be...

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Bibliographic Details
Published in:Environmental pollution (1987) 2006-10, Vol.143 (3), p.468-478
Main Authors: Evans, C.D., Caporn, S.J.M., Carroll, J.A., Pilkington, M.G., Wilson, D.B., Ray, N., Cresswell, N.
Format: Article
Language:English
Subjects:
acidification
Applied sciences
Atmospheric deposition
Atmospheric pollution
Carbon - chemistry
carbon nitrogen ratio
carbon sequestration
Earth sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Environmental Monitoring - methods
Exact sciences and technology
Geochemistry
heathland soils
Humans
immobilization in soil
leachates
leaching
Models, Theoretical
Nitrate leaching
Nitrogen - chemistry
nitrogen content
Nitrogen saturation
Pollutants physicochemistry study: properties, effects, reactions, transport and distribution
Pollution
Pollution, environment geology
simulation models
Soil and rock geochemistry
Soil carbon
Soil Pollutants - chemistry
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Summary:A simple model of nitrogen (N) saturation, based on an extension of the biogeochemical model MAGIC, has been tested at two long-running heathland N manipulation experiments. The model simulates N immobilisation as a function of organic soil C/N ratio, but permits a proportion of immobilised N to be accompanied by accumulation of soil carbon (C), slowing the rate of C/N ratio change and subsequent N saturation. The model successfully reproduced observed treatment effects on soil C and N, and inorganic N leaching, for both sites. At the C-rich upland site, N addition led to relatively small reductions in soil C/N, low inorganic N leaching, and a substantial increase in organic soil C. At the C-poor lowland site, soil C/N ratio decreases and N leaching increases were much more dramatic, and soil C accumulation predicted to be smaller. The study suggests that (i) a simple model can effectively simulate observed changes in soil and leachate N; (ii) previous model predictions based on a constant soil C pool may overpredict future N leaching; (iii) N saturation may develop most rapidly in dry, organic-poor, high-decomposition systems; and (iv) N deposition may lead to significantly enhanced soil C sequestration, particularly in wet, nutrient-poor, organic-rich systems. Enhanced carbon sequestration may slow the rate of nitrogen saturation in heathlands.
ISSN:0269-7491
1873-6424
DOI:10.1016/j.envpol.2005.12.004