Comparative assessment of bio-fertiliser quality of cow dung and anaerobic digestion effluent

The elevated use of inorganic fertilizers due to poor soil quality and the need for an increase in food production to meet the demand of the increasing global population has led to fertility decline in soil. Anaerobic digestion for the production of biogas and digestate is considered a sustainable alternative to non-renewable energy and inorganic fertilisers respectively. In this study, the potential use of anaerobic digestate as an alternative to dung as fertilizer was evaluated. The digestate and dung samples were screened for plant growth promoting bacteria (PGPB), the nutrient and heavy metal contents. The dung contained higher concentrations of heavy metals, phosphorus and potassium (p < 0.05). The identified genera from both samples include Acinetobacter, Bacillus, Pseudomonas, Escherichia, Staphylococcus and Micrococcus. The presence of higher amounts of mineralised nitrogen, reduced heavy metal content and PGPB in the digestate highlighted the potential ability of the digestate to enhance soil fertility