Detection of microbial activity in some organic amendments

ABSTRACT

@#Aims:In this paper we conducted a laboratory experiment to assess the biological characters and maturity level of three organic materials filter cake (FC), spent mushroom substrate (SMS) and fermented grass (FG), through microbial activity and phytotoxicity.Methodology and results:Each sample was determined for physicochemical parameters, microbial activity and phytotoxicity. Microorganism population was counted by spreading plate method and microbial activities were tested by measuring fluorescein diacetate (FDA) hydrolysis and dehydrogenase activity (DHA). The phytotoxicity evaluation by seed germination was tested on Hibiscus sabdariffa (Roselle),Abelmoschus esculentus (Okra) and Oryza sativa (Rice). The results showed that all substrates have suitable physicochemical values that could be used as soil amendments. These organic matters are a rich source of microorganisms (>107 CFU/g), especially plant growth promoting bacteria (ranging from 104 to 106CFU/g). The high value of FDA (ranging from 1.609 to 1.621 mg/g) and DHA activity (ranging from 153.95 to 179.92 μg/g)suggested a high degree of microbial activity in the organic amendment samples. Combining with germination index values in seed germination, most GI values indicate non-toxicity of those substrates, with the exception of fermented grass in germination of H.sabdariffa.Conclusion, significance and impact of studyThe result from this study proposes that these substrates can be considered as potential amendments to support soil property.