Nutritional controls on carbon dioxide and methane emission from Carex-dominated peat soils

Eutrophication of peatlands may have significant effects on emissions of carbon dioxide and methane. This study analyses the effects of nitrogen (28.7 mmol NH4+N, N), phosphorus (1.78 mmol PO43−P, P) and glucose (2.79 mmol glucose, G) additions on CO2 and CH4 emission from intact soil cores from a Carex-dominated peatland in the Netherlands. The cores (taken from the upper 10 cm of the peat profile) were brought to field capacity and aerobically incubated at 20°C for 6 wk. Nutrients were added in the following combinations: 0 (unfertilized control), N, P, NP, G, NG, PG, NPG. All treatments in which glucose was present (G, NG, PG, NPG) stimulated CO2 emission during the first 2 wk of the experiment, but did not lead to increased decay of organic matter. At the end of the experiment, all treatments which included N (N, NG, NP, NPG) showed reduced CO2 emission. This was probably due to pH effects, because the pH in the N fertilized treatments was 0.4–0.8 units lower than in the unfertilized control. Cumulative CO2 emission in the N treatment was lower than in the control, but in the treatments where glucose was added it was higher. There was no effect of P addition on CO2 emission. In all treatments, cumulative CH4 emission was higher than in the control due to an initial stimulation of CH4 emission. Compared within treatments, cumulative CO2C emission was 35–164 times higher than cumulative CH4C emission. From these observations we conclude that increased amounts of NH4+N supply lead to reduction of decay of organic matter in peat soils and thereby to a reduction of gaseous carbon loss from these soils. Nutrient or glucose additions lead only to a short-term increase in methane emissions from peat soils.