Efficacy of urease inhibitor with and without nitrification inhibitor in improving efficiency of urea-based fertilizers
Why this work is in the frame
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Bibliographic record
Abstract
Nitrogen (N) losses in the form of ammonia volatilization limit the efficiency of urea-based fertilizers world-wide. Urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT) is a promising additive to reduce this N loss. Studies were conducted to test the efficacy of a relatively new NBPT formulation, ARM U (18% NBPT m/v), containing a proprietary polymer that allows for a low NBPT application rate in reducing ammonia volatilization from urea-based fertilizers. The results showed that ARM U reduced ammonia volatilization by an average of 85% across three soils and its effectiveness was not significantly different from other commercial NBPT formulations whose NBPT concentrations were 33-67% greater than ARM U. Further studies showed that delaying N fertilizer application until late-fall, as recommended on the Canadian prairies, did not stop ammonia volatilization from urea-based fertilizers. Across 4 site-year, total ammonia volatilization (% of applied N) from untreated urea-based fertilizers applied in the fall and spring were 14 and 16%, respectively. We found that the reduction of ammonia volatilization by NBPT was significantly greater in the fall (65%) than in the spring (40%) across 4 site-year and the addition of NI with NBPT (double inhibitor, DI) reduced the efficacy of NBPT in decreasing ammonia volatilization from spring-applied urea by 27%. The conserved N by NBPT and DI improved the crop N use efficiency at one of the two sites in this study. Investigation on the interaction between NBPT and NI on urea hydrolysis in five soils at 21 oC and six soils at 5, 15, and 25 oC showed that while NBPT reduced the rate of urea hydrolysis across soils and temperatures, the addition of NI reduced the inhibitory effect of NBPT on urea hydrolysis. Hence, reduction in ammonia volatilization is less with DI than only NBPT. Overall, the research shows that (i) NBPT effectively reduced ammonia volatilization even at a low concentration (ii) significant ammonia volatilization could occur from urea-based fertilizers even at soil temperature below 3 oC (iii) use of NBPT to bridge crop urea use efficiency is site-specific (iv) NI impaired the effectiveness of NBPT in suppressing urea hydrolysis and ammonia volatilization.
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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) | 0.001 | 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 it