Saturday, 15 July 2006

Biochemical,enzymatic and humic fraction transformations during composting of urban and agricultural residues.

Bhargavi M.V, University of Agricultural Sciences, GKVK, Bangalore, Bangalore-65, India

Biochemical, Enzymatic and Humic fraction transformations during composting of urban and Agricultural residues. Aye Aye Thant ; Bhargavi,M.V ; Dr.V.R.R.Parama ; Bhanu Prakash, U. H. 1. Senior Research Fellow, Dept. of Soil Science & Agril. Chemistry, UAS, GKVK, Bangalore-65 2. Associate Professor, Dept. of Soil Science & Agril. Chemistry, UAS, GKVK, Bangalore-65. 3 Ph.D Student, Dept. of SS & AC, UAS, GKVK, Bangalore-65 Abstract Soil health sustenance is key to continued soil productivity. Organic matter serves as of soil health. Tropical countries like India need to utilize alternative sources of organic resources such as agricultural, agro industrial and urban organic residues to convert them into enriched humus source there by enhancing environmental quality. Therefore organic matter, the life of soil needs to be provided. Towards this end urban and domestic waste composts could serve as a valuable source of organic matter given the shortage of organic matter. In this context urban (UW) waste made of vegetables, fruits and kitchen left overs etc. from Bangalore city was composted with selected organic residues such as poultry cage litter, poultry deep litter, areca husk, bagasse, coir pith and press mudand other residues (OR) in 2:1 ratio (UW :OR) Cow dung and microbial consortia consisting of Phaenerochete chrysosporium and Tricoderma harzianum (@ 105 CFU) was used as starters (microbial inoculum) to initiate decomposition process. Composting was carried out for a period of four months (120 days). Turning was given at an interval of 15 days so as to facilitate aeration and decomposition. Samples drawn at each intervals were air dried, crushed, pulverized and then analyzed using standard procedure for the biochemical parameters (Lignin, Cellulose and Total Phenols); Enzymatic changes (namely Acid and alkaline phosphatase, Urease and Cellulase) and the humic fractions (Humic acid, Fulvic acid) were studied Over the period of composting it was observed that the biochemical parameters such as Lignin, Cellulose and total Phenol content decreased which is an indication of microbial degradation and transformation of these components. About 30-43% of cellulose was decomposed in all the treatments over a period of four months (120 days). Variation in the enzyme activity was observed in all the treatments. Maximum Acid and Alkaline phosphatase, Urease and Cellulase was observed on 30th day of composting. However a constant trend in enzyme activity was not observed but the activity decreased by 120 days. Humification process also showed a varied trend. Fulvic acid content decreased while the Humic acid content showed an increasing trend. The increase in levels of humic acid were employed as a criteria to assess the degree of maturity. In corollary the C: N ratio stabilized at around 12:1 indicating maturity. By 120 days the organic residues mediated by microbial transformations was converted to value added ecofriendly composts rich in nutrients. The study indicates that resistant biochemical fractions Viz, lignin and cellulose transforms via microbially mediated enzyme activity leading to increased humic fractions. These transformations serve to convert organic residues into nutrient rich organic matter. Hence bioconversion serves as a ecofriendly mechanism in waste recycling.

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