Greenhouse gas and ammonia emission mitigation priorities for UK policy targets

Acknowledgements Many thanks to the Association of Applied Biologist’s for organising and hosting the ‘Agricultural greenhouse gases and ammonia mitigation: Solutions, challenges, and opportunities’ workshop. This work was supported with funding from the Scottish Government’s Strategic Research Programme (2022-2027, C2-1 SRUC) and BBSRC (BBS/E/C/000I0320 and BBS/E/C/000I0330). We also acknowledge support from UKRI694 BBSRC (United Kingdom Research and Innovation-Biotechnology and Biological Sciences 695 Research Council; United Kingdom) via grants BBS/E/C/000I0320 and BBS/E/C/000I0330. and Rothamsted Research's Science Initiative Catalyst Award (SICA) supported by BBSRC.Peer reviewedPublisher PD

Addition of base cations increases microbial carbon use efficiency and biomass in acidic soils

The leaching of base cations in acidic soils can result in calcium (Ca2+) and magnesium (Mg2+) deficiencies, which are important for microbial cell function. We aimed to determine if microbial carbon use efficiency (CUE) and microbial biomass carbon (MBC) were limited in acidic soils due to a lack of base cations. Microbial CUE across a range of agricultural soils (n = 970; pHCa 3.4–7.9) treated with either deionised H2O (control) or a solution of 300 mM CaCl2 + 300 mM MgCl2 (+Base cations) was determined using a14C radioisotope tracer approach. Our results showed that the addition of base cations significantly increased microbial CUE (by up to 20%) at pHCa < 4.7; which coincided with a steep increase in exchangeable acidity. Base cation addition significantly increased MBC in nil-limed soils (pHCa 4.6) from 494 mg C kg−1 to 769 mg C kg−1 when plant residue was added, but not in limed soils (pHCa 6.2). Our findings indicate that the addition of base cations to highly acidic soils can increase microbial growth, thus aiding with carbon sequestration in these agricultural soils