Integrative fertilizer nitrogen management mitigates nitrogen leaching and gray water footprint in a subtropical vegetable rotation system
Why this work is in the frame
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Bibliographic record
Abstract
• Annual N leaching in subtropical open-field vegetable fields averaged 251 kg ha −1 , representing 29% of applied N fertilizer. • Optimizing rate and timing of N fertilizers reduced N leaching by 68%. • Nitrification inhibitor reduced N leaching and gray water footprint more effectively than controlled-release urea or mixed organic-inorganic fertilizers. • Integrative “4R” N stewardship produced more vegetables with less N leaching. Nitrogen (N) leaching is a major pathway of N loss in subtropical crop production systems, contributing to groundwater pollution and thus posing serious threats to human health. However, the characteristics of annual N leaching in subtropical open-field vegetable systems and the effectiveness of integrative N fertilization management practices in reducing N leaching remain poorly understood. In this study, two plot-based field experiments were conducted with open-field Chinese cabbage-pepper rotation system in subtropical southwest China to quantify annual N leaching and evaluate the effectiveness of integrated N fertilization management practices. Experiment 1 compared five N fertilizer application rates using conventional urea, while Experiment 2 compared different N sources including conventional urea, organic fertilizer, nitrification inhibitor-based fertilizer, and controlled-release urea which were all applied at the optimized N rate. Results showed that the annual N leaching under farmers’ N practice (FNP) was 251 kg N ha −1 , with contributions of 55, 31, and 14% from the pepper season, Chinese cabbage season, and fallow period, respectively. Total N leaching increased exponentially with N rate. The seasonal N leaching factor was 32% for pepper and 17% for Chinese cabbage in the FNP treatment, respectively. Compared to FNP, optimizing N rate based on crop requirement and soil supply significantly reduced N leaching by 68% and gray water footprint by 66−75%, while improving N use efficiency (NUE) from 35% to 54%. In Experiment 2, mixing organic and inorganic fertilizers, applying nitrification inhibitor, and using controlled-release urea further reduced annual N leaching by 27, 54, and 25%, respectively, compared to conventional urea. These practices also improved crop yields by 2−11% and NUE by 10−13%, and lowered gray water footprint by 28−58%. In summary, integrative N stewardship practices, particularly use of nitrification inhibitors under optimized N rates, effectively reduced N leaching while achieving high NUE and vegetable yields, providing a promising strategy for sustainable subtropical vegetable production.
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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) | 0.000 | 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 it