Manure and bio-manure substitutions of chemical fertilizers mitigate long-term nitrous oxide emissions from vegetable production systems
Bibliographic record
Abstract
Substituting chemical fertilizers with manure or bio-manure (manure inoculated with microbes) offers a promising strategy to mitigate nitrous oxide (N 2 O) emissions, yet the underlying mechanisms remained unclear. Through a five-year field study employing isotopocule (δ 15 N SP N2O and δ 18 O N2O/H2O ) mapping, we elucidated that a 50% substitution with manure or bio-manure significantly decreased cumulative N 2 O emissions by suppressing production of nitrification- and nitrifier-denitrification- and heterotrophic denitrification (HD)-derived N 2 O, and promoted N 2 O reduction to N 2 in denitrification. In contrast, 20% substitutions failed to achieve sustained mitigation. Bio-manure initially exhibited stronger N 2 O mitigation than manure, but this mitigation effect disappeared over time due to a N 2 O production–consumption offsetting effect in HD. Specifically, relative to manure, bio-manure stimulated HD-driven N 2 O production in association with increasing abundances of HD-related genes ( nirK , nirS , fungi- nirK ) and potential denitrification rates. Bio-manure often maintained a higher capacity for N 2 O reduction, evidenced by lower ( nirK + nirS+ Fungi- nirK )/( nosZ ) ratios and unreduced N 2 O fraction. Critically, substitutions enhanced crop yields, with manure increasing yields by 8–21% and bio-manure by 19–30% compared to conventional fertilizer. Consequently, our study revealed that 50% bio-manure substitution is an effective strategy for mitigating N 2 O emissions and enhancing yields from vegetable production systems, providing actionable insights for sustainable resource management and climate change mitigation. • N 2 O source partitioning under bio-manure (BM) and manure (M) substitutions • BM promoted the reduction of N 2 O to N 2 compared with M • Either 50% M or 50% BM reduces N 2 O emissions based on a 5-year field trial • Production-consumption balance in denitrification governs N 2 O flux in BM vs M • The mitigation advantage of BM vs M diminishes under long-term application
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".