Journal article

Publication year: 2023

Journal: Soil Biology and Biochemistry

Volume number: 184

ISSN: 0038-0717

eISSN: 1879-3428

Open access status: Hybrid

DOI Link: https://doi.org/10.1016/j.soilbio.2023.109114

Publisher: Elsevier

Abstract: 
Incorporation of nitrogen (N) into soil microbial protein is central to the soil N cycle to mitigate N losses and support plant N supply. However, the effect of factors, such as water filled pore space (WFPS), which influence inorganic N transformations and losses, and thus microbial incorporation, are only poorly understood. This work aimed to bridge this gap, using compound-specific N-15-stable isotope probing to quantify microbial assimilation into the largest defined soil organic N pool, protein-N. This approach applied differentially N-15-labelled ammonium nitrate (NH4NO3) to an unfertilised UK grassland in a soil mesocosm study over 10 days. The soil microbial community showed a strong preference for NH4+ over NO3-, which varied with WFPS (85% > 55% > 70%). This preference decreased for amino acids further in biosynthetic proximity to the transamination step in amino acid biosynthesis. Combined incorporation of NH4+ and NO3- increased total hydrolysable amino acid-N concentration linked to WFPS (55% similar to 85% > 70%). Incorporation rates of applied N-15 showed the same trend as NH4+ preference with WFPS (85% > 55% > 70%), which is related to microbial activity and nutrient mobility. Despite differences in incorporation, when normalised to soil available N, incorporation was comparable in the short-term. Mechanistic control of WFPS via assimilation into the largest soil organic N pool is important to mitigate potential positive feedbacks to N losses and support N supply to plants.

Harvard Citation style: Reay, M., Loick, N., Evershed, R., Müller, C. and Cardenas, L. (2023) Moisture effects on microbial protein biosynthesis from ammonium and nitrate in an unfertilised grassland, Soil Biology and Biochemistry, 184, Article 109114. https://doi.org/10.1016/j.soilbio.2023.109114

APA Citation style: Reay, M., Loick, N., Evershed, R., Müller, C., & Cardenas, L. (2023). Moisture effects on microbial protein biosynthesis from ammonium and nitrate in an unfertilised grassland. Soil Biology and Biochemistry. 184, Article 109114. https://doi.org/10.1016/j.soilbio.2023.109114