Nitrification and nitrous oxide production potentials in aerobic soil samples from the soil profile of a Finnish coniferous site receiving high ammonium deposition

Abstract

Using aerobic soil slurry technique nitrification and nitrous oxide production were studied in samples from a pine site in Western Finland. The site received atmospheric ammonium deposition of 7–33 kg N ha−1 a−1 from a mink farm. The experiments with soil slurries showed that the nitrification potential in the litter layer was higher at pH 6 than at pH 4. However, the nitrification potentials in the samples from the organic and mineral horizons at pH 6 and 4 were almost equal. Also N2O was produced at a higher rate at pH 6 than at pH 4 in slurries of the litter layer samples. The reverse was true for samples from the organic and mineral horizons. The highest N2O production and nitrification rates were measured in the suspensions of litter layer samples. Nitrification activity in field‐moist soil samples was lower than the activity in the slurries indicating that the availability of ammonium limited nitrification in these soils. Acetylene (2.5 kPa) retarded nitrification activity (70‐–100%) and N2O production (40 – 90%) in soil slurries. Acetylene inhibited the N2O production by 40–60% during the first 3 days after its addition to field‐moist samples incubated in aerobic atmosphere. After 3 days the inhibition became much lower (4–5%). The results indicate that, in soil profiles of boreal coniferous forests receiving ammonium deposition, chemolithotrophic nitrification may have importance in the N2O production, and that changes in soil pH affect differently nitrification as well as N2O production in litter and deeper soil layers.

Does nitrate fertilization induce nox emission from scots pine (p. sylvestris) shoots?

“…In natural conditions, microbes living in the soil, soil moisture and pH all affect the NH4+/NO3-balance, among other things. Nitrification in fertilized Finnish forest soils is favored by high pH (Paavolainen and Smolander 1998), but it can occur even in acidic soils, especially if the soil is rich in ammonium (De Boer et al 1990;Martikainen et al 1993;Persson and Wirén 1995;Paavolainen and Smolander 1998). Denitrification, on the other hand, is favored by high soil moisture, high nitrate concentration, high pH and high temperature (Federer and Klemedtsson 1988;Willison and Anderson 1991;Haselwandter 1991, 1997).…”

Soil greenhouse gas and nutrient dynamics in fertilized western Canadian plantation forests

“…Nitrogen impacts on soil biogeochemical and greenhouse dynamics are complex and likely depend on the timing of fertilization and chemical species involved, environmental conditions, and edaphic and ecosystem properties. Nitrogen additions can potentially enhance N 2 O emissions through microbial nitrification (Martikainen et al 1993) and denitrification (Pang and Cho 1984) and can either stimulate CH 4 oxidation by supplying a limiting nutrient to CH 4 oxidizing bacteria (Bodelier et al 2004) or inhibit oxidation by causing osmotic stress (Schnell and King 1996) or through enzymatic inhibition of CH 4 monooxygenase by ammonium (NH 4 + ) (Dunfield and Knowles 1995). Microbial decomposition of soil organic matter and CO 2 production following N or N and other nutrient additions have been inconsistent (Neff et al 2002).…”

Interactive effects of MnO2, organic matter and pH on abiotic formation of N2O from hydroxylamine in artificial soil mixtures

“…High pH can lead to an increase of chemical N 2 O production involving nitrite by favoring nitrite accumulation, either directly through increasing nitrite stability, or indirectly by inhibiting biological nitrite oxidation due to a higher concentration of free NH 3 (an inhibitor of nitrite oxidizers) in the soil 28 . In contrast, high soil N 2 O emissions have also been observed in acid forest soils 29 30 . In this case, the effect of pH on enzyme activities during denitrification and nitrification was suggested as the main reason 31 .…”