Nitrous oxide emissions and nitrate leaching in relation to microbial biomass dynamics in a beech forest soil

• Published in: Soil biology & biochemistry Vol. 34; no. 6; pp. 823 - 832
• Main Authors: ZECHMEISTER-BOLTENSTERN, Sophie, HAHN, Maria, MEGER, Simone, JANDL, Robert
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Science 01.06.2002; New York, NY
• Subjects: Agronomy. Soil science and plant productions; Allium ursinum; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; Central Europe; Austria; Europe; Organic carbon; Monocotyledones; Organic nitrogen; Cambisols; Gas emission; Growth; Carbon dioxide; Forest soil; Biogeochemical cycle; Microbial biomass; Leaching; Liliaceae; Nitrogen cycle; Silt loam soil; Dynamics; Mineralization; Seasonal variation; Angiospermae; Nitrification; Denitrification; Spermatophyta; Nitrogen protoxide
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(02)00012-3

In a 140 year-old beech forest with undergrowth of Allium ursinum, field measurements of N sub(2)O and CO sub(2) emissions in conjunction with measurements of microbial biomass-N, extractable mineral nitrogen and NO sub(3) super(-)-leaching were made during four vegetation growth periods. We examined whether pulses of nitrate leaching could be accompanied by enhanced N sub(2)O emission rates. Highest N sub(2)O emission rates (> 150 mu g N m super(-2) h super(-1)) were recorded during July, when substantial nitrate leaching also was evident from ion exchange resins and suction cup lysimeters. These nitrogen losses were preceded by mineralisation of decaying Allium leaves and microbial proliferation in June. In July, a significant decline of microbial biomass nitrogen occurred and up to 113 kg N ha super(-1) were released. Microbial biomass carbon, as determined from substrate induced respiration, also declined in July. With this method, we identified recurring cycles of microbial growth triggered by soil wetting. Soil microbial biomass carbon related inversely to concentrations of extractable sugar carbon substrates. Our study suggests that within nitrogen-enriched forests, nitrate leaching and N sub(2)O emissions may be linked during the plant growing season. Nitrogen losses appeared to be strongly affected by biomass turnover and microbial mineralisation.