Effects of increased deposition of atmospheric nitrogen on an upland moor: Nitrogen budgets and nutrient accumulation

Pilkington, Michael G., Caporn, Simon J.M., Carroll, Jacqueline A., Cresswell, Neil, Lee, John A., Reynolds, Brian and Emmett, Bridget A. (2005) Effects of increased deposition of atmospheric nitrogen on an upland moor: Nitrogen budgets and nutrient accumulation. Environmental pollution, 138 (3). pp. 473-484. ISSN 0269-7491

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Abstract

This study was designed to investigate the effect of long-term (11 years) ammonium nitrate additions on standing mass, nutrient content (% and kg ha−1), and the proportion of the added N retained within the different compartments of the system. The results showed that more than 90% of all N in the system was found in the soil, particularly in the organic (Oh) horizon. Added N increased the standing mass of vegetation and litter and the N content (kg N ha−1) of almost all measured plant, litter and soil compartments. Green tissue P and K content (kg ha−1) were increased, and N:P ratios were increased to levels indicative of P limitation. At the lowest treatment, most of the additional N was found in plant/litter compartments, but at higher treatments, there were steep increases in the amount of additional N in the underlying organic and mineral (Eag) horizons. The budget revealed that the proportion of added N found in the system as a whole increased from 60%, 80% and up to 90% in response to the 40, 80 and 120 kg N ha−1 year−1 treatments, respectively. Additions of 40 kg N ha−1 over 11 years accumulated mainly in plant and litter compartments; higher additions accumulated mainly in the organic and mineral horizons.