Nitrous oxide productivity of soil fungi along a gradient of cattle impact

• Eighty out of 164 fungal isolates (48.8%) were considered as N2O producers.
• 33 fungal species of 23 different genera exhibited N2O producing activity.
• N2O production was newly reported in various fungal genera.
• Highly productive fungi were isolated from soils under current cattle impact.
• N2O-producing fungi are common constituent part of biota in cattle-impacted soils.

The objective of the study was to identify N2O-producing fungi isolated from six qualitatively different sections of an overwintering pasture with substantial cattle impact. 80 out of 164 fungal isolates were considered as N2O-producers in nitrite-containing medium, representing 33 fungal species of 23 different genera. Ability to produce N2O was newly reported in eight genera: Arthrinium, Gibellulopsis, Ilyonectria, Lichtheimia, Paraphaeosphaeria, Purpureocillium, Tolypocladium and Westerdykella. Three levels of fungal N2O-productivity were assigned according to the fraction of nitrite-N transformed into N2O–N: < 1%, 1–10%, over 10%. Fungi capable of high and moderate transformation rates were predominantly isolated from sections under current or past cattle impact, where they contributed with a maximum of 65% of the total N2O emissions. There was no significant effect of cultivation conditions on the fraction of N2O-producing fungi. The results demonstrate that N2O-producing fungi are a common constituent of fungal communities in soils impacted by overwintering cattle.