Impact of animal dung on soil pH and microbiota: A study of two medium-scale livestock farms in Ibadan, Oyo state, Nigeria

Abstract

This study investigated the impact of animal-dung on soil pH and microbiota. Soil samples from five different livestock litters were collected from two medium-scale livestock farms in Ibadan, Oyo-State. These included litter-free soil with pH 7 (control), and soil samples from dungs of poultry, pig, goat and cattle. Physicochemical properties of each soil sample were assessed according to Association Official Analytical Chemist (AOAC) procedures. Total bacterial count and total fungi count of each sample were determined using standard pour plate technique. Fungi and soil health-indicator bacteria including cellulolytic, amylolytic, proteolytic, phosphate-solubilizing, nitrogen-fixing bacteria and actinobacteria were isolated and identified using cultural characteristics, biochemical tests and molecular techniques. Data obtained were subjected to descriptive statistics and analysis of variance (ANOVA) at p = 0.05. Results showed that pH value was lowest (5.48) in cattle dung soil and highest (5.78) in pig dung soil. Cellulolytic, amylolytic, proteolytic, phosphate-solubilizing, nitrogen-fixing bacteria and actinobacteria were identified. Microbial analyses showed that soil samples from pig dung had relatively higher count (65.5 x 10⁶ CFU/ml) of heterotrophic bacteria and total fungi count (15.75 x 10 ⁶ CFU/g) than other soil samples. Isolates subjected to molecular identification were identified as P. aeruginosa, B. cereus, K. pneumoniae, B. substilis and B. thuringiensis with 99% similarity search identity. Statistical analysis revealed that relationship exists between the physicochemical parameters and microbes isolated as r > 0. This study established soil acidification caused by poorly managed litters which impact soil microbiota.