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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730
EISSN: 2072-6589
Vol. 5, No. 2, 1997, pp. 147-159
Bioline Code: cs97021
Full paper language: English
Document type: Research Article
Document available free of charge

African Crop Science Journal, Vol. 5, No. 2, 1997, pp. 147-159

 en Grain yield of wheat as affected by cropping sequence and fertilizer application in southeastern Ethiopia
Taa, Asefa; Tanner, D.G.; Girma, Kefyalew & Gorfu, Amanuel

Abstract

Cropping systems in the Ethiopian highlands consist primarily of cereals in rotation with grain legume and oilseed crops; the proportional allocation among crop species varies with altitude, rainfall, and soil type. Barley (Hordeum vulgare L.) tends to dominate in the highest altitudinal zones, while bread wheat (Triticum aestivum L.) is more common at medium altitudes on well-drained soils. A trial was established in 1992 at the Kulumsa and Asasa research sites in southeastern Ethiopia to evaluate interactions among wheat-based cropping sequences and annual applications of inorganic nitrogen (N) and phosphorus (P) fertiliser. Rotational crops included Ethiopian rapeseed (Brassica carinata L.), faba bean (Vicia faba L.), and barley. The results indicated significant rotational effects on wheat grain yield (GY), including enhanced GY in dicot vs. cereal rotations, in two year vs. three year rotations, in first year wheat after any break crop, and in rotation with faba bean vs. rapeseed. Interactions among cropping sequences and N and P fertiliser were also significant. Response to N was markedly reduced in two year rotations with any break crop, in first year wheat after any break crop, and after faba bean, in particular; this reflected higher soil N status in these cropping sequences. Conversely, P response was significantly enhanced in two year rotations and in the first wheat crop after any break crop, and in dicot-based rotations, particularly with faba bean. Presumably, this enhancement was the result of simultaneous improvement in soil N status and a reduction in wheat root pathogen and grass weed populations in these cropping sequences.

Keywords
Barley, crop rotation, faba bean, grain yield, nitrogen, phosphorus, rapeseed, Triticum aestivum, weed density

 
 fr
Taa, Asefa; Tanner, D.G.; Girma, Kefyalew & Gorfu, Amanuel

Résumé

Les systemes de culture sur les hauts plateaux ethiopiens reposent essentiellement sur la rotation cereales-legumineuses-oleagineux. Les proportions relatives des differentes cultures varient avec l'altitude, les precipitations et les conditions edaphiques. L'orge (Hordeum vulgare L.) domine a haute altitude, tandis que le ble tendre (Triticum aestivum L.) se rencontre plutt aux altitudes intermediaires sur des sols bien draines. Un dispositif experimental a ete mis en place en 1992 dans les centres de recherche de Kulumsa et d'Asasa dans le sud-est ethiopien afin d'evaluer, l'interaction entre le schema de rotation et l'application annuelle d'engrais inorganique azote (N) et phosphore (P) au sein des systemes a base de ble. Le colza ethiopien (Brassica carinata L.), la feve (Vicia faba L.) et l'orge ont ete utilises comme cultures de rotation. Les resultats montrent un effet significatif de la rotation sur le rendement en grains du ble (RG): une rotation ble-dicotyledones se traduit par un RG plus eleve qu'une rotation ble-cereales; un cycle de rotation de deux ans conduit a un RG plus eleve qu'un cycle de trois ans; le RG augmente apres n'importe quelle culture de rotation; le RG de ble en rotation avec de la feve est superieur a celui de ble en rotation avec du colza. On observe egalement une interaction significative de la rotation culturale-fertilisation N et P. La reponse a la fertilisation N connait une importante diminution dans une rotation de deux ans quelle que soit la plante utilisee en rotation; on observe egalement une reduction en premiere annee apres n'importe quelle plante alternative, dans les rotations ble-dicotyledones et plus particulierement dans le cas de la feve. Ces resultats refletent la plus haute teneur du sol en azote dans les schemas de rotation consideres. Inversement, la reponse au phosphore augmente dans les rotations de deux ans, pendant la premiere annee apres n'importe quelle plante alternative, et dans les rotations a base de dicotyledones, en particulier la feve. On suppos que cette augmentation correspond aux effets combines de ces schemas de rotation : amelioration du bilan azote dans le sol, reduction des populations d'adventices et de pathogenes de la racine de ble.

Mots Clés
Azote, ble, colza, densite d'adventices, feve, orge, rendement en grains, rotation, phosphore, Triticum aestivum

 
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