Measurements of net soil-atmosphere carbon dioxide exchange and its oxygen and carbon isotope composition in incubations of soil sampled from 44 sites in western Eurasia and northeastern Australia

Soils were sampled from 27 sites in western Eurasia during 2016 and 17 sites in northeastern Australia during 2017. Triplicate replicate microcosm incubations were created from homogenised soil from each site. The net soil-atmosphere exchange of carbon dioxide and its oxygen and carbon isotope composition between the soil and atmospheric was measured under two different headspace conditions using a custom built gas-exchange system. Subsequently the pH, microbial biomass and the availability of ammonium and nitrate were determined for incubated soils. An additional fertlisation experiment, consisting of a 0.7 mg addition of ammonium nitrate per gram of dry soil, was conducted on soils from 14 sites. The data from these incubations are reported along with the characteristics of the original sampling sites.