Effect of some edaphic factors on microbial decomposition of leaf fiber biomass of Toona ciliata Roxb. and Trema orientalis BI.

Abstract

Leaf fiber residue generated as a by-product during the bulk production of leaf protein from forest tree leaves poses disposal problems in the absence of any proper utilisation. The fiber residue can be returned to the forest floor for mineralization as a soil amendment. A short term in vitro study was conducted to determine the microbial population and activity as well as the rate of decomposition of the mixture of leaf fiber residues from two perennial plants viz. Toona ciliata Roxb. and Trema orientalis Bl. in the forest soil in relation to moisture, temperature and pH. The most favourable condition for microbial association and fiber decomposition was found to be 25% moisture content at 35°C and 6.5 pH for microbial association and fiber decomposition. Effects of temperature, moisture and pH on the species composition of fungal flora associated with decomposition were also investigated. Aspergillus, Mucor, Rhizopus, Trichoderma, Penicillium, Cladosporium, etc. were the most common genera isolated from decaying fibrous residues, which ultimately governed the decomposition of leaf fiber in the soil. Some species of Aspergillus such as A. flavus, A. fumigatus, A. nidulans, A. terreus, and some species of Penicillium, Sporotrichum and Thichoderma were found 10 survive at 50°C.