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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730
EISSN: 2072-6589
Vol. 5, No. 1, 1997, pp. 87-92
Bioline Code: cs97011
Full paper language: English
Document type: Short Communication
Document available free of charge

African Crop Science Journal, Vol. 5, No. 1, 1997, pp. 87-92

 en Influence of molybdenum and cobalt fertilisation on symbiotic nitrogen fixation indicators in an oxisol in Uganda
Tenywa, J.S.


Molybdenum (Mo) and cobalt (Co) are important micro-elements involved in biological N2-fixation. Uganda has embarked on a campaign to increase the productivity of legume crops through utilisation of rhizobial inoculants, unfortunately, non-responsiveness is frequently encountered. Among the suspected causes are inadequacies of Mo and Co supply in the soil. A glasshouse study was, therefore, conducted with an Oxisol to examine this relationship. Treatments included provision of lime at 0 and 1.0 t ha-1, Mo at 0, 390 and 780 g ha-1 and Co at 0, 454 and 907 g ha-1. Soybean (Glycine max Merrill) cultivar NAM.1 was the test crop. Cobalt application at a rate of 454 g ha-1 resulted in the greatest nodulation and number of effective nodules per plant, as well as total N accumulation in the shoots. Liming depressed soil solution acidity by 0.2 pH units. A combination of lime (1 t CaCO3 ha-1) and Co (454 g ha-1) increased nodulation and the number of effective nodules per plant, but masked cobalt's positive effect on total N accumulation in shoots. Liming alone did not affect the biological N fixation indicators considered in this study.

Biological nitrogen fixation, inoculation, liming, soybean

Tenywa, J.S.


Le molybdene (Mo) et le Cobalt (Co) sont des micro-elements importants pour la fixation d'azote biologique. L'Ouganda mene une campagne pour elever la productivite des legumes en utilisant des inoculations Rhizobiales, mais souvent sans succes. Parmi les raisons possible, on a de quantites insuffisantes de Mo et Co dans le sol. Pour examiner cette relation, une etude a ete conduite dans la serre avec un Oxisol. On utilisait des concentrations sub-normales de la chaux, Mo et Co. Le soya (Glycine max Maerril), cultivar NAM.1 etait teste. L'application de 454 g/ha de Co resultait en une nodulation elevee et une augmentation du nombre de nodules effectives par plante, mais aussi dans l'accumulation d'azote totale. L'application de la chaux diminuait l'acidite du sol avec 0.2 unites de pH. Une combinaison de chaux (1 t CaCO3/ha) et Co (454g/ha) augmente la nodulation et le nombre de nodules effectives par plante, mais masquait l'effet positive de l'accumulation de l'azote totale dans les pousses. L'application uniquement de la chaux n'influencait pas les indicateurs de fixation biologique N dans cette etude.

Mots Clés
la fixation d'azote biologique, inoculation, chauler, le soya

© Copyright 1997 - African Crop Science Society

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