ISSN: 2471-9315
Ogbonna CB, Stanley HO and Abu GO
The aim of this study was to investigate the effect of liquid digestate (produced from anaerobic digestion of organic municipal solid waste) on the population dynamics of selected soil microbial groups during cultivation of maize plants. Maize seeds where subjected to various concentrations (between 0% to 72%) of the digestate with a total of ten (10) runs. One set of experimental runs were treated with one-time application of the corresponding digestate concentration (OTDA). Another set of experimental runs were treated with two-time application of the corresponding digestate concentration (TTDA). The first application of the digestate (for OTDA and TTDA) was conducted two weeks after sowing while the second application (for TTDA alone) was conducted three weeks after the first application. During the growth of maize plants, the populations of soil aerobic bacteria (AEB), strict anaerobic bacteria (SAB), ammonia oxidizing bacteria (AOB), nitrate reducing bacteria (NRB) and fungi (FUN) where monitored using standard cultural methods. In OTDA and TTDA treatments, the population of soil AEB, SAB, AOB, NRB and FUN ranged from 3.0 × 106 CFU/g to 50.2 × 106 CFU/g and 3.1 × 106 CFU/g to 78.6 × 106 CFU/g; 1.9 × 104 CFU/g to 7.2 × 105 CFU/g and 2.2 × 104 CFU/g to 2.53 × 105 CFU/g; 0MPN/g to 4.3 × 104 MPN/g and 0MPN/g to 3.9 × 105 MPN/g; 0 MPN/g to 4.4 × 105 MPN/g and 0 MPN/g to 1.4 × 105 MPN/g and 1.3 × 103 CFU/g to 2.6 × 104 CFU/g and 1.2 ×103 CFU/g to 9.4 × 103 CFU/g respectively before and 70 days after applying the digestate. Bacteria species isolated appear to belong to genera such as Arthrobacter, Azotobacter, Flavobacterium, Nocardia, Bacillus, Clostridium, Cellulomonas, Micrococcus and Pseudomonas. Fungi species isolated appear to belong to genera such as Aspergillus, Cladosporium, Fusarium, Geotrichum, Penicillium, Rhizopus and Trichoderma. Digestate application appears to have increased the population of soil microbes with time during the cultivation of maize plants.