Impact assessment of cement industry activities on soil nitrogen-fixing bacteria

Abstract

Nitrogen fixing bacteria play a vital role in transforming atmospheric nitrogen into inorganic form easily available for plant use. However, environmental pollution due to effluent from industrial activities could accumulate in soil, significantly altering the soil chemical and microbiological characteristics, such as nitrogen fixing bacteria. The effect of cement dust on nitrogen-fixing bacteria is presented in this study. Homogenized soil samples 0-20 cm in depth from the cement factory and other communities 200m-2km away from the factory were evaluated for soil physicochemical properties and nitrogen-fixing bacterial bioload using standard procedures. Soil pH, total nitrate, and total phosphate decreased as distance increased away from the factory. Elevated conductivity values of 605.94-621.80(µs/cm) was recorded for soil samples from the factory, indicating the presence of higher dissolved solutes. Total culturable Azotobacter count increased as distance increased away from the factory lcation, with SR1 (Akinbo) recording the highest of 10 4 -10 5 cfu/g, while Azospirillium and Clostridium count significantly reduced. Pollution due to cement production activities may not have had a significant negative effect on the bioload of nitrogen-fixing bacteria. A higher amount of nitrate in soil samples around the cement plant showed that nitrogen-fixing activities occurred at a lower rate compared to the locations farther away from the cement plant.