Impacts of land use on soil microbial biomass and soil organic status in Western Cameroon

Abstract

Living organisms and their enzymes are responsible of most of the soil biotic interactions in agro-ecosystems. This study was to evaluate the impact of land use (cropping systems and farming practices) on the physical, chemical and biological properties of soil in Western Cameroon. We sampled soil (0-20 cm) in four different land use systems (extensive, intermediate, intensive and an undisturbed natural habitat). We also measured soil health indicators in each land use type.  We observed that the total organic carbon (C_org) and P availability was significantly higher in agro-ecosystems as compared to undisturbed natural habitat. Similar trends were recorded for pH, electrical conductivity, and ?-glucosidase, dehydrogenases and acid phosphatase activities. We also recorded a significant variation in microbial biomass C (C_mic: 312.0 to 544.5 mg kg^-1 dry soil) and microbial biomass N (N_mic: 5.40 to 25.31 mg kg^-1 dry soil) with land use intensity. The C_mic/C_org ratios of soils were two-fold lower in agricultural lands with vegetables than the undisturbed control plot indicating a decrease in soil microorganisms. Regression analysis revealed a negative correlation (r = - 0.806, P < 0.01) between soil clay content and microbial biomass C, and a high C_org/N ratio suggesting a heterogeneous distribution of the population of microorganisms between soils and the immobilization of P, respectively. Our results suggest that the selected soil health indicators were sensitive to farming practices and cropping systems.

Keywords: Farming practices, cropping systems, microbial biomass, enzymes activities, field conditions, tropical soil quality, Western Cameroon.