Table 1: Different values used for conversion factor from acetylene reduced to N2 fixed

Source Conversion factor Reference
Theoretical average 3 or 4 Hardy et al. [51]
Jenson and Cox [192]
Legumes, non-legumes and soils 2.6 - 6.9 Hardy et al. [51]
Anaerobic soil 25 Hardy et al. [51]
Suspensions of bacteria 2-8 - 4.7 Hardy et al. [51]
Montoya et al. [193]
Overall range 0.56 - 22 Boddey et al. [59, 61]
Anabaena (17.3 oC) 3.96 Liengen [111]
Anabaena (14.0 oC) 4.88 Liengen [111]
   Cyanobacterial crusts 0.0216-0.073
   Nostoc community 0.11-0.48
Sub-alpine meadow & coniferous forest 7.5 Skujins et al. [194]
Saline soils 2.1 - 2.8 Zechmeister-Boltenstern and Kinzel [195]
Peat soils 5.4 Zechmeister-Boltenstern and Kinzel [195]
Grassland, wheat fields, fallow 3.1-8.6 Steyn and Delwiche [52]
Forest soils Nohrstedt [196]
   Low water (75% of water saturation) 2.6
   High water (100% water saturation) 15.7
Forest soils 1.6-5.6 Nohrstedt [197]
Decomposing litter 3.9 Vitousek and Hobbie [198]
Coastal sediments 0.11 - 94 Seitzinger and Gaber [199]

Note: It has been suggested that conversion factors >4 may be associated with higher solubility of acetylene whereas < 3 values are attributed to the nutritional N limitation caused by incubation with acetylene [200, 201].