Ammonia Volatilization Loss from Surface-Broadcast Urea: Comparison of Vented- and Closed-Chamber Methods and Loss in Winter Wheat?Summer Maize Rotation in North China Plain
Notice bibliographique
Résumé
Ammonia (NH3) volatilization is an important pathway for fertilizer nitrogen (N) loss from soil and is also a major source of air and environmental pollution. On calcareous soils in North China Plain, application of N fertilizer in the form of urea under intensive cropping with winter wheat (Triticum aestvum L.) and summer maize (Zea mays L.) rotation can lead to serious NH3 loss. The objective of this study was to compare a modified vented-chamber method with the traditional closed-chamber method to measure NH3 volatilization loss under laboratory and field conditions and to determine in situ NH3 volatilization in the field from surface broadcast urea at 0, 120, 240, and 360 kg N ha−1 rates to each crop (for winter wheat, one-half at sowing and the other half at the elongation growth stage; for summer maize, one-half at the 3-leaf and the other half at the 10-leaf growth stage) in a winter wheat and summer maize rotation at the northern edge of North China Plain from October 1998 to September 1999. Urea was surface applied after irrigation before sowing, or prior to irrigation during the growing season. Compared to the closed chamber method, the vented chamber method was found to be simpler in structure, easier to operate, more suitable for in situ determination of NH3 volatilization in the field, and had higher recovery of emitted NH3 (99.5 vs. 70.8%). For surface broadcast urea after first irrigation prior to sowing of winter wheat, the NH3 volatilization rate reached, a maximum on the second to fifth day after application. Total NH3 loss from soil during the October 8 to November 18, 1998, period was 2.9, 4.8, 10.5, and 35.7 kg N ha−1 at the 0, 60, 120, and 180 kg N ha−1 rates, respectively. When urea was top-dressed prior to irrigation at the elongation growth stage of the winter wheat in midspring, NH3 loss was relatively low (i.e., 1.5, 2.1, 2.4, and 2.7 kg N ha−1 at 0, 60, 120, and 180 kg N ha−1 rates, respectively). The NH3 loss from urea for the entire winter wheat–growing season accounted for 2.1, 3.6, and 9.5% of the applied N at 120, 240, and 360 kg N ha−1 rates, respectively. For summer maize where urea was top-dressed at the 3-leaf and 10-leaf growth stages, the NH3 volatilization rate increased more quickly and maximized on the first or second day after N application. During the summer maize–growing season, total NH3 loss from urea accounted for 5.6, 4.8, and 4.9% of the applied N at 120, 240, and 360 kg N ha−1 rates, respectively. Based on the results of this study, total NH3 loss was estimated to range from 163,000 to 477, 200 Mg of N from soil in a winter wheat–summer maize rotation in North China Plain. Of these, about 68,400 to 382,600 Mg of N loss were from the N fertilizer surface applied as urea.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,002 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».