Epsilon Open Archive

Abstract

This study investigates microbial communities in soil from
sites under different land use in Kenya.
We sampled natural forest, forest plantations, agricultural
fields of agroforestry farms,agricultural fields
with traditional farming and eroded soil on the slopes of Mount Elgon,Kenya. We hypothesised that microbial decomposition capacity, biomass and diversity 1)decreases with intensified cultivation; and 2)can be restored by soil and land management in agroforestry.
Functional capacity of soil microbial communities was estimated by degradation of 31 substrates on Biolog EcoPlates™. Microbial community composition and biomass were
characterised by phospholipid fatty acid (PLFA)and microbial
C and N analyses. All 31 substrates were metabolised in
all studied soil types, i.e. functional diversity did not differ. However,both the substrate utilisation rates and the microbial biomass decreased with intensification of land use, and the biomass was positively correlated with organic matter content. Multivariate analysis of PLFA and Biolog EcoPlate™ data showed clear differences 25
between land uses, also indicated by different relative abundance of PLFA markers for certain microorganism groups.
In conclusion, our results show that vegetation and land use control the substrate utilisation capacity and microbial community composition and that functional capacity of depleted soils can be restored by active soil management, e.g. forest plantation. However, although 20 to 30 years of agroforestry farming practises did result in
improved soil microbiological and chemical conditions
of agricultural soil as compared to traditional agricultural
fields, the change was not statistically significant.