ISSN 2756-3693
African Journal of Biology Vol. 1 (2), pp. 089-094, November, 2013. © International Scholars Journals
Full Length Research Journal
Estimates of biological nitrogen fixation by Pterocarpus lucens in a semi arid natural forest park in Senegal using 15N natural abundance method
Sylla S N1*, Ndoye I1, Gueye M2, Ba A T1 and Dreyfus B3
1UCAD, Faculté des Sciences et Techniques, Département de BV, BP 5005, Dakar, Sénégal. 2MIRCEN/Centre ISRA-IRD, BP 1386, Dakar, Sénégal.
3LSTM, IRD _ CIRAD, TA10/J, Campus de Baillarguet, 34398, Montpellier, France.
Accepted 15 May, 2013
*Corresponding author; e-mail: [email protected], tel: +221-8 49 33 22, fax: +221-8 32 16 75
Abstract
Nitrogen (N2) fixation by Pterocarpus lucens in a natural semi arid ecosystem, in Ferlo, Senegal was estimated using 15N natural abundance (∂15N) procedure. Other non-fixing trees accompanying P. lucens in the same area were also investigated as control. Results showed an important variation of ∂15N in leaves between the nitrogen-fixing tree (P. lucens) and reference plants, whereas no significant differences were recorded in amount of nitrogen (%). The relative ∂15N values (‰) were higher in non-fixing plants than in fixing plants considered. Calculations of %Ndfa gave rates ranging between 26% and 49%. The values of %Ndfa depend largely on soil and the reference plants. The contribution of nitrogen derived from fixation in leaves reached 28.9 kg.N/ha and 10.8 kg.N/ha in ferruginous and in sandy soil respectively.
Key words: Pterocarpus lucens, 15N natural abundance, semi arid lowland, biological nitrogen fixation, natural ecosystem.