Potential and Observed Release of Phosphorus from Crop Residue and Cover Crops Over the Non-growing Season in a Cool Temperate Region
Notice bibliographique
Résumé
Maintaining crop residue or cover crops on fields during winter is a recommended Best Management Practice (BMP) in temperate regions. However, losses of phosphorus (P) to runoff have been attributed to vegetation following freeze-thaw cycles (FTC). Much of the existing knowledge on P loss from vegetation following FTC has been obtained under severe frost conditions (either simulated or natural). In cool temperate climates, such as Southwestern Ontario, air temperatures are more moderate. Consequently, crop residue and cover crops may be less severely impacted by FTC. An improved understanding of the role of surface vegetation in P losses during the non-growing season (NGS) in cool temperate climate zones is needed to determine if the use of cover crops is suitable for these regions. This thesis addresses two major objectives: (1) to better understand the potential role of hydroclimatic conditions (FTC and hydrological event type) in mobilizing P from crop residue, Triticum aestivum L. (winter wheat), as well as Trifolium pretense L. (red clover) and Avena sativa L. (oat) as cover crops, using laboratory experimentation; and (2) to quantify the release of P from vegetation and soil over the NGS in a field setting, and, determine if changes in water extractable phosphorus (WEP) in vegetation or soil were reflected in loads of dissolved reactive phosphorus (DRP) or total phosphorus (TP) in surface runoff and tile drain effluent. Results from this study revealed that the patterns observed in the laboratory were reflected in the field, where cover crops released more P than winter wheat residue. Oat cover crop was impacted by FTC whereas red clover was not, likely because it had been terminated in early fall using a herbicide. The laboratory and field experiments also demonstrated that potential losses of P from cover crops do not necessarily translate to losses of P in runoff because the mobilization of P in runoff is impacted by both supply and transport processes. Phosphorus leaching and loss from fields are hampered if crops are not inundated/flooded or if surface runoff is limited, but enhanced when vegetation is subjected to prolonged contact with runoff water. The field study demonstrated that although P appeared to have been mobilized from both vegetation and soil pools during the NGS, loads of DRP P and TP leaving the fields were small in comparison, suggesting that much of the P released was retained within the field rather than lost in runoff. This study provides insight into the timing and magnitude of P release from vegetation throughout the NGS in regions with a cool temperate climate and provides an improved understanding of the contribution of cover crops to winter P losses.
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| 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 ».