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- Title
Intended and unintended impacts of nitrogen‐fixing microorganisms and microbial inhibitors on nitrogen losses in contrasting maize cropping systems.
- Authors
Souza, Emerson F. C.; Rosen, Carl J.; Venterea, Rodney T.; Tahir, Muhammad
- Abstract
Efforts to mitigate the nitrogen (N) footprint of maize production include using N‐fixing microbes (NFM) and/or microbial inhibitors. We quantified the effects of NFM, the nitrification inhibitor (NI) 2‐(N‐3,4‐dimethyl‐1H‐pyrazol‐1‐yl) succinic acid isomeric mixture, and the urease inhibitor (UI) N‐(n‐butyl) thiophosphoric triamide, each applied by itself or paired with another additive, on nitrous oxide (N2O) emissions, nitrate (NO3−) leaching, and crop performance in contrasting irrigated and rainfed maize systems over two growing seasons. We also used published emission factors to estimate indirect N2O emissions from leached NO3− that can be converted to N2O. Agronomic effects were relatively small; the NI + NFM treatment increased N use efficiency and grain yield and protein content in some cases by 11%–14% relative to a treatment receiving only urea. Most of the additive treatments reduced direct (in‐field) N2O emissions, most consistently for treatments that contained NI which reduced emissions by 24%–77%. However, these beneficial effects were counteracted by increased NO3− leaching, which occurred most consistently with UI or NFM applied as single additives or with NI. In these treatments, NO3− leaching increased during at least one growing season, and at both sites, by factors of 2–7. In three site‐years, increased NO3− leaching with NFM and NI + NFM offset large reductions in direct N2O, such that total direct + indirect N2O emissions were not different from that in the urea only treatment. These unintended effects may have resulted from unfavorable rainfall timing, varying crop N demand, and declining additive effectiveness. Use of these soil additives requires caution and further study. Core Ideas: Effects of soil additives on nitrate (NO3−) and nitrous oxide (N2O) losses at two maize sites were assessed.The nitrification inhibitor DMPSA consistently reduced N2O losses.Adding nitrogen (N)‐fixing microbes or the urease inhibitor NBPT increased NO3− leaching.Increased NO3− leaching offset the benefits of reduced N2O in some cases.Unintended impacts of soil additives on N losses require caution and further study.
- Subjects
NITROGEN-fixing microorganisms; CROPPING systems; NITRIFICATION inhibitors; SUCCINIC acid; GROWING season; NITROGEN-fixing bacteria; AZOTOBACTER
- Publication
Journal of Environmental Quality, 2023, Vol 52, Issue 5, p972
- ISSN
0047-2425
- Publication type
Article
- DOI
10.1002/jeq2.20500