Short-Term Soil Nitrous Oxide Emissions as Affected by Enhanced Efficiency Nitrogen Fertilizers and Temporarily Waterlogged Conditions
Bibliographic record
Abstract
<p> </p><p>Poorly-drained claypan soils in the Midwestern United States experience periods of short-term soil saturation shortly after pre-plant N fertilization, which may result in relatively large amounts of soil surface N<sub>2</sub>O emissions. Slowing the release or conversion of N fertilizer to soil NO<sub>3 </sub>early in the growing seasonthrough the use of enhanced efficiency fertilizers (EEF) could be an effective strategy for reducing soil N<sub>2</sub>O emissions and gaseous N loss during a period of relatively low plant N demand. The objective of this study was to determine the effects of short-term soil waterlogging and pre-plant applications of conventional and EEF on soil inorganic N and N<sub>2</sub>O emissions during and up to four days following a waterlogging event during the dry down period. A two-year field study planted to corn (<em>Zea mays </em>L.) was initiated in 2012 on a poorly-drained claypan soil in Northeast Missouri. Waterlogging treatments were initiated at the V6 corn stage of phenological development. Main plots consisted of no waterlogging or water ponded 7 to 13 cm above the soil surface for three days, and sub-plot N fertilizer treatments [non-treated control (CO), or preplant broadcast applications of 168 kg N ha<sup>-1</sup> of urea (NCU), urea plus nitrapyrin nitrification inhibitor (NCU+NI), and polymer coated urea (PCU)]. In 2012, greater cumulative soil N<sub>2</sub>O-N emissions of 2.8 kg N<sub>2</sub>O-N ha<sup>-1</sup> were observed with PCU in comparison to NCU over the entire seven day sampling period. A significant portion of cumulative soil N<sub>2</sub>O emissions were associated with the four day soil drying phase in 2012, where PCU and NCU+NI had greater emissions (1.9 and 1.2 kg N<sub>2</sub>O-N ha<sup>-1</sup>) compared to NCU. The proportion of N fertilizer lost as N<sub>2</sub>O-N averaged over all pre-plant N treatments during the 2012 and 2013 sampling periods in the non-waterlogged soils were 0.04% and 0.03%, and 1.1% and 2.6% in the waterlogged soils, respectively. These results suggest that a large proportion of the cumulative soil surface N<sub>2</sub>O emissions typically observed in these poorly-drained soils over a growing season may occur during and shortly after soil waterlogging events.</p>
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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 | 0.001 |
| Science and technology studies | 0.001 | 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".