Nitrous oxide emissions from soil amended with untreated liquid manure (slurry), anaerobically digested slurry, or inorganic fertilizers (calcium ammonium nitrate or urea) were quantified in a field study covering two growth seasons of spring barley ( Hordeum vulgare L.). In the first year incorporation before seeding was compared with trail hose application 5 wk after seeding. In the second year all fertilizers were applied before seeding, while soil moisture and initial NO − 3 availability was varied. Accumulated N 2 O losses between the time of fertilization and ca. 1 July represented 0.14 to 0.35% of total N in 1996 and 0.34 to 0.64% in 1997. In both years the highest N 2 O emissions were observed with untreated slurry, whereas digested slurry and inorganic fertilizers were at a similar level. Increasing the soil moisture content or NO − 3 availability had no significant effect on accumulated N 2 O losses. Although metabolizable C may thus have stimulated N 2 O emissions via denitrification from untreated slurry, the largest contribution to N 2 O fluxes probably came from nitrification with all fertilizer types. Using the IPCC guidelines it was estimated that anaerobic digestion of slurry per se could potentially reduce N 2 O emissions from Danish agriculture by 1.2 to 2.5%.
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S. O. Petersen (1999) studied this question.