POPULATION DENSITY OF ARBUSCULAR MYCORRHIZAL FUNGI AND PHYSICO-CHEMICAL PROPERTIES OF SOILS AS AFFECTED BY CROPPING SYSTEMS

Cropping pattern exerts significant impact on the population density of the arbuscular mycorrhizal fungi (AMF) and on soil properties. The study examined the population of indigenous AMF communities as well as status of soil properties under different cropping systems in Aluu, Rivers state, Nigeria. Two farm sites of mono cropping and mixed cropping systems and a fallow land (which served as control) were sampled at 0 – 20 cm depth of soil. Soil samples were analyzed in the laboratory for their physical and chemical properties as well as for the estimation of AMF spore density and resulting data were analyzed statistically. Result shows that, soils of the mono cropping and mixed cropping systems are moderately acidic with mean pH values of 5.80 and 5.74, respectively, while the fallow land exhibits a strongly acid soil reaction (pH = 5.29). Concentrations of organic C (9.25 g kg-1), total N (0.97 g kg-1), exchangeable Ca2+ (3.63 cmol kg-1), available P (13.31 mg kg-1) and C:N ratio (7.87) as recorded in the mixed cropping system, were generally higher than the corresponding results in the fallow and mono cropping systems. Spore population of the AMF varied significantly (P < 0.05) across the cropping systems and was highest in the mixed cropping (157 spores 100 g-1 soil) followed by the fallow (144 spores 100 g-1 soil) while the mono cropping (123 spores 100 g-1 soil) had the lowest spore density. Significant negative (P < 0.05) correlations occurred between AMF spore population and soil pH in both the fallow (r = 0.689*) and mixed cropping (-0.670*) systems whereas correlation with C:N ratio was positively significant (P < 0.01) across the cropping systems. Adoption of mixed cropping rather than mono cropping practices should be encouraged in the studied area in order to enjoy maximum benefits of mycorrhizal symbiosis.