The effect of nitrogen fertilization and no‐till duration on soil nitrogen supply power and post–spring thaw greenhouse‐gas emissions
Notice bibliographique
Résumé
Abstract With a world population now > 7 billion, it is imperative to conserve the arable land base, which is increasingly being leveraged by global demands for producing food, feed, fiber, fuel, and facilities ( i.e. , infra‐structure needs). The objective of this study was to determine the effect of varying fertilizer‐N rates on soil N availability, mineralization, and CO 2 and N 2 O emissions of soils collected at adjacent locations with contrasting management histories: native prairie, short‐term (10 y), and long‐term (32 y) no‐till continuous‐cropping systems receiving five fertilizer‐N rates (0, 30, 60, 90, and 120 kg N ha –1 ) for the previous 9 y on the same plots. Intact soil cores were collected from each site after snowmelt, maintained at field capacity, and incubated at 20°C for 6 weeks. Weekly assessments of soil nutrient availability along with CO 2 and N 2 O emissions were completed. There was no difference in cumulative soil N supply between the unfertilized long‐term no‐till and native prairie soils, while annual fertilizer‐N additions of 120 kg N ha –1 were required to restore the N‐supplying power of the short‐term no‐till soil to that of the undisturbed native prairie soil. The estimated cumulative CO 2 ‐C and N 2 O‐N emissions among soils ranged from 231.8–474.7 g m –2 to 183.9–862.5 mg m –2 , respectively. Highest CO 2 fluxes from the native prairie soil are consistent with its high organic matter content, elevated microbial activity, and contributions from root respiration. Repeated applications of ≥ 60 kg N ha –1 resulted in greater residual inorganic‐N levels in the long‐term no‐till soil, which supported larger N 2 O fluxes compared to the unfertilized control. The native prairie soil N 2 O emissions were equal to those from both short‐ and long‐term no‐till soils receiving repeated fertilizer‐N applications at typical agronomic rates ( e.g. , 90 kg N ha –1 ). Eighty‐eight percent of the native soil N 2 O flux was emitted during the first 2 weeks and is probably characteristic of rapid denitrification rates during the dormant vegetative period after snowmelt within temperate native grasslands. There was a strong correlation ( R <?h.3> 2 0.64; p < 0.03) between measured soil Fe‐supply rate and N 2 O flux, presumably due to anoxic microsites within soil aggregates resulting from increased microbial activity. The use of modern no‐till continuous diversified cropping systems, along with application of fertilizer N, enhances the soil N‐supplying power over the long‐term through the build‐up of mineralizable N and appears to be an effective management strategy for improving degraded soils, thus enhancing the productive capacity of agricultural ecosystems. However, accounting for N 2 O emissions concomitant with repeated fertilizer‐N applications is imperative for properly assessing the net global warming potential of any land‐management system.
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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 | 0,000 |
| 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 ».