Dry-season autotrophic and heterotrophic soil respiration in contrasting agroecological settings

ABSTRACT In arid Africa, it is unclear how the transition from grassland to cropland affects CO2 fluxes and whether these effects are climate-dependent. From November 2019 to March 2020 (dry season), we studied autotrophic (Ra) and heterotrophic (Rh) soil respiration. At highlands, grazing land (1.18 ± 0.13 µmol m−2 s−1) and teff croplands (1.36 ± 0.14 µmol m−2 s−1) had the lowest Rh, while acacia decurrens plantations (1.94 ± 0.19 µmol m−2 s−1) were the largest. When compared to teff (2.08 ± 0.20 µmol m−2 s−1) and khat (1.73 ± 0.24 µmol m−2 s−1), grazing land in the midland had a lower Rh (1.18 ± 0.13 µmol m−2 s−1). Ra on teff (1.51 ± 0.27 µmol m−2 s−1) was substantially (P < 0.05) greater than on grazing land (1.08 ± 0.32 µmol m−2 s−1) in the highlands. Grazing lands (1.54 ± 0.21 µmol m−2 s−1) have a considerably (P < 0.05) greater Ra than farmlands (teff, 0.20 ± 0.07 µmol m−2 s−1; groundnut, 0.09 ± 0.03 µmol m−2 s−1) in lowlands. Growing teff in the highlands and midlands will result in higher CO2 fluxes into the atmosphere. However, in-depth research is needed to implement effective land management that reduces CO2 emissions.