Nitrous Oxide Emitted from Soil Receiving Anaerobically Digested Solid Cattle Manure
Bibliographic record
Abstract
Limited information is available about soil nitrous oxide (N 2 O) fluxes, N 2 O emission factors (EFs), and yield‐scaled N 2 O 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 N 2 O 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 N 2 O flux occurred within 36 d of applying digestate, separated solids, and cattle manure, respectively. The cumulative N 2 O emissions with digestate were 4.7 and 4.1 times the values of the separated solids and cattle manure, respectively. The digestate N 2 O EF was 13.6 and 10.6 times the values of the separated solids and cattle manure, respectively, but the N 2 O EF based on applied mineral N was similar for all amendments. The yield‐scaled N 2 O 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 N 2 O emissions than both the separated solid fraction of the biogas residues and undigested cattle manure. Core Ideas Information on N 2 O emitted from biogas residues applied to semiarid soils is limited. 80 to 95% of N 2 O emissions occurred within 36 d of amendment application over 4 yr. Digestate led to 4.4 times the N 2 O emissions of separated solids and cattle manure. Digestate had 10.6 to 13.6 times the N 2 O emission factors of separated solids and cattle manure. Digestate had 4.0 times the yield‐scaled N 2 O of separated solids and cattle manure.
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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 | 0.001 | 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 | 0.001 |
| Open science | 0.001 | 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".