Full Length Research Paper

Dynamics of culturable soil microbial communities during decomposition of some agroforestry species in a semi arid and arid tropical agroecozones of West Africa

Okoh, A. I.¹* and Tian, G.²

¹Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.

²Environmental Monitoring and Research Division, Research and Development Department, Metropolitan Water Reclamation District of Greater Chicago (MWRD-Chicago), Lue-Hing R&D complex, 6001 W. Pershing Road, Cicero, IL 60804, USA.

*Corresponding author. E-mail: aokoh98@yahoo.com.

Accepted 1 August, 2008

Field litterbag studies were conducted during the dry season between years 2000 and 2001 in typical semi-arid and arid agroecozones of West Africa to measure the dynamics of culturable bacterial and fungal communities in the topsoils. Five different agroforestry leaf litters namely Dactyladenia, Pterocarpus, Alchonea, Senna, and Gliricidia species were decomposed, and their effects on soil microflora were studied. Bacterial densities in all the studied plots of the two agroecozones varied from the order of 10⁸ to 10¹⁰ cfu/g, while fungal densities ranged in the order of 10³ and 10⁴ cfu/g. Ecological zones impacted significantly (P < 0.05) on bacterial proliferation, but not on fungal growth. Sampling period significantly (P < 0.05) affected microbial density and the semi-arid agroecozone was more supportive of microbial proliferation than the arid zone. A total of nine predominant fungal species belonging to the genera Aspergillus, Scopulariopsis, Alternaria, Penicillium, Micromonospora, Trichophyton and Neurospora were observed in both the semi-arid and arid agroecozones, although their distributions under both agroecozones did not follow any definite pattern.

Key words: Microflora types, agroforestry topsoil, culturable microbes, bacteria, fungi, soil enrichment.