Moisture effects on microbial protein biosynthesis from ammonium and nitrate in an unfertilised grassland

A - Papers appearing in refereed journals

Reay, M. K., Loick, N., Evershed, R. P., Muller, C. and Cardenas, L. M. 2023. Moisture effects on microbial protein biosynthesis from ammonium and nitrate in an unfertilised grassland. Soil Biology and Biochemistry. 184, p. 109114. https://doi.org/10.1016/j.soilbio.2023.109114

AuthorsReay, M. K., Loick, N., Evershed, R. P., Muller, C. and Cardenas, L. M.
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 15N-stable isotope probing to quantify microbial assimilation into the largest defined soil organic N pool, protein-N. This approach applied differentially 15N-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% ~ 85% > 70%). Incorporation rates of applied 15N 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.

KeywordsOrganic nitrogen ; Water filed pore space; Compound-specific; Amino acids; 15N-stable isotope probing
Year of Publication2023
JournalSoil Biology and Biochemistry
Journal citation184, p. 109114
Digital Object Identifier (DOI)https://doi.org/10.1016/j.soilbio.2023.109114
Open accessPublished as ‘gold’ (paid) open access
FunderNatural Environment Research Council
Biotechnology and Biological Sciences Research Council
Funder project or codeReducing the Impacts of Plastic Waste in Developing Countries
Elucidating the importance of the pools of nitrate in soils on denitrification
S2N - Soil to Nutrition - Work package 1 (WP1) - Optimising nutrient flows and pools in the soil-plant-biota system
S2N - Soil to Nutrition - Work package 2 (WP2) - Adaptive management systems for improved efficiency and nutritional quality
National Environmental Isotope Facility
Publisher's version
Supplemental file
Output statusPublished
Publication dates
Online28 Jun 2023
Publication process dates
Accepted27 Jun 2023
PublisherElsevier
ISSN0038-0717

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