Phosphorus use efficiency and long-term trends in soil available phosphorus in wheat production systems with and without nitrogen fertilizer
Notice bibliographique
Résumé
Selles, F., Campbell, C. A., Zentner, R. P., Curtin, D., James, D. C. and Basnyat, P. 2011. Phosphorus use efficiency and long-term trends in soil available phosphorus in wheat production systems with and without nitrogen fertilizer. Can. J. Soil Sci. 91: 39–52. Efficient use of phosphorus (P) in crop production is important for economic and environmental reasons, and to prolong the life of a limited resource. Short-term studies often show low recovery of fertilizer P, but P use efficiency may be underestimated because the value of residual P in the soil is ignored. Our objective was to determine fertilizer P use efficiency in two wheat production systems [continuous wheat (CW) and a 3-yr rotation of summer fallow-wheat-wheat (FWW)] using data from a 39-yr study (1967–2005) at Swift Current, SK. Each rotation received either P only (P) or nitrogen plus P (NP) fertilizer. Annual grain P removal was monitored (all straw was returned to the soil) and changes in soil available P (0- to 15-cm layer) were measured by the Olsen bicarbonate method. In 1993, subplots which received no additional P were established to evaluate the residual effect of P fertilizer applied in the preceding 27 yr. Where P was applied each year, grain P removal averaged 54 to 78% of fertilizer P, with values as high as 65 to 109% in 1994 to 2005, the period of lowest water deficit. The P-only treatments removed 13% less P in grain, on average, than NP treatments. In the P-nly systems, Olsen P content increased linearly with time, but in the NP systems it reached a maximum after 20–22 yr and then stabilized. The cumulative P balance (fertilizer P minus P removed in grain) accounted for 60% of the variability in Olsen P accumulation over the course of the experiment. In CW, Olsen P content increased by 0.15 kg ha −1 for each kg ha −1 of P added in excess of crop removal. The rate of Olsen P accumulation was greater (0.20 kg ha −1 for each kg ha −1 of excess fertilizer P) in the FWW rotation possibly due to P mineralization during the summer fallow year. When P was withheld between 1994 and 2005, total grain production in the CW rotation was reduced slightly (by 10%), but there was no significant effect on FWW. Crop P removal (1967–2005) where P was withheld in the final 12 yr was equivalent to 105 and 90% of fertilizer P added to the NP and P-only systems, respectively. We concluded that residual P in prairie soils is retained in forms that are available to plants; wheat crops may therefore recover close to 100% of applied fertilizer P given sufficient time.
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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 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| 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 ».