Nitrous Oxide Emitted from Soil Receiving Anaerobically Digested Solid Cattle Manure
Bibliographic record
Abstract
Limited information is available about soil nitrous oxide (N2O) fluxes, N2O emission factors (EFs), and yield‐scaled N2O emissions for biogas residues used to fertilize crops in semiarid regions. To address this knowledge gap, a 4‐yr field experiment was conducted in a semiarid climate to determine growing season N2O fluxes from soil receiving (i) anaerobically digested solid beef cattle manure (digestate), (ii) separated solids from the digestate (separated solids), and (iii) undigested solid beef cattle manure (cattle manure) applied to target one and two times the recommended rates (200 and 400 kg total N ha−1) for barley (Hordeum vulgare L.) forage, assuming 50% of N was annually plant available. Nitrous oxide fluxes were determined using vented static chambers. Over the four growing seasons, 95, 80, and 81% of the N2O flux occurred within 36 d of applying digestate, separated solids, and cattle manure, respectively. The cumulative N2O emissions with digestate were 4.7 and 4.1 times the values of the separated solids and cattle manure, respectively. The digestate N2O EF was 13.6 and 10.6 times the values of the separated solids and cattle manure, respectively, but the N2O EF based on applied mineral N was similar for all amendments. The yield‐scaled N2O emissions with digestate were 4.3 and 3.6 times the values of the separated solids and cattle manure, respectively. In the semiarid region of southern Alberta, liquid biogas residues have a higher risk for N2O emissions than both the separated solid fraction of the biogas residues and undigested cattle manure. Core Ideas Information on N2O emitted from biogas residues applied to semiarid soils is limited. 80 to 95% of N2O emissions occurred within 36 d of amendment application over 4 yr. Digestate led to 4.4 times the N2O emissions of separated solids and cattle manure. Digestate had 10.6 to 13.6 times the N2O emission factors of separated solids and cattle manure. Digestate had 4.0 times the yield‐scaled N2O of separated solids and cattle manure.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 | 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 source (direct Gemma or distilled Codex), 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".