Soil microbial status under different land use systems in Gombe state, Nigeria

Microorganisms are of primary importance for soil quality and natural productivity. Four land use systems viz., Forestry, Horticulture, Agriculture and Pasture at four different locations viz., Bajoga, Gombe, Boderi and Kanawa were identified in determining population of microorganisms in the soil. The samples were collected, numbered and labelled with date and site of collection in an air-tight pre-sterilized polyethene bags before transportation to the laboratory. Serial dilution pour plate technique was used for estimation of total bacterial, fungal, actnomycetes and azotobacter using specific media. The plates were incubated at temperatures specific to particular microbe for 2 – 3 days. The colonies that developed on media were counted by electronic colony counter. The microbial counts were expressed as colony forming unit per gram of soil (CFU/g soil). The highest bacterial count (CFU/g) was found in forest land use with the mean value (192.66) and the lowest (41.33) was found in agricultural land use system. The highest total fungal count (CFU/g) was recorded in forest land use with the mean value (77.33) and the lowest (10.33) was found in agricultural land use system. The highest total viable actinomycetes count (CFU/g) was recorded in forest land use with the mean value (62) and the lowest (3) was found in agricultural land use system as compared to other soils in the study area. The perusal of data reveals that for the total azotobacter count (CFU/g), the highest was recorded in forest soils because of the presence of more organic matter with mean value (22.66) as compared with the other land use systems. The lowest was found in agriculture (4.33).  Lowest microbial count in agricultural soils may result to poor soil quality and natural productivity which may lead to famine a natural disaster. Planting of cover crops will improve soil structure, enhance soil fertility and sustain or increase soil organic matter and soil biological activity.