Vermicomposting using paddy straw as Published in The Hindu

VERMICOMPOSTING is an appropriate technique for efficient recycling of animal wastes, crop residues and agro-industrial wastes. Paddy strawis a wide C:N (80:1) organic material, low in nitrogen and phosphorus but fairly rich in potassium. In conventional method of composting, paddy straw takes 6-8 months for decomposition resulting in a poor quality of compost. The process of conversion of organic materials into manure is chiefly microbiological and greatly influenced by the proportion of carbonaceous and nitrogenous materials present in organic wastes.
Microorganisms need carbon for cell structure formation and nitrogen for cellular protein synthesis. It was found that C:N ratio of 30:1 or lower for raw material was desirable for efficient composting. Organic materials poor in nitrogen content (wide C:N ratio) decompose slowly, take more time and result in lower amount of compost formation. Under the situation, the biological activity diminishes and several successions of organisms may be required to degrade the carbonaceous materials. So, C:N ratio of organic materials poor in nitrogen should be made narrow by adding nitrogen in the form of any nitrogenous fertilizer to it for better decomposition.
Superphosphate is generally added to fortify the phosphorous content of the compost. It also checks the volatilisation loss of NH{-3} from the decomposable mass during the process of compost formation.
Earthworm activities are important in aiding faster decomposition process mainly done by microbial actions. It grinds the organic waste materials in the gizzard and the actions of bacteria therein hasten the decomposition process. The number of bacteria and actinomycetes increased 1000 fold during passage of substrate through the gut.
Besides, aeration, mixing and turning over the materials are essential in decomposition process which are also done by earthworms. An experiment was conducted in Orissa taking red earthworm (Eisenia foetida) for the decomposition of paddy straw in presence of fertilizer sources to add N and P. Dried and chopped (3-4 cm) paddy straw, after thorough mixing with fresh cowdung slurry was introduced into pots. Nitrogen in the form of calcium ammonium nitrate (CAN) was applied to raise the N level of the straw to 2 per cent N and phosphorus as Single Super phosphate (SSP) to raise the total P{-2}O{-5} content to 0.2 per cent. In control, no such additional fertilizer N or P was added. Watering was done to pots to maintain the moisture content to 40-50 per cent.
After two week of preliminary decomposition, red earthworms were released at 10 adults per pot.
The pots were covered with gunny bag to maintain moisture and temperature under shed.
This prevents worms from crawling outside the waste material and also to prevent entry of other insects. Ten weeks after the initiation of the composting process, the compost masses were collected.
The experimental results showed neutral reaction of the compost masses indicating their suitability for soil application.
The straw decomposition was (91 per cent by vermiculture in presence of fertilizer N & P which was greater than the control.
The C:N ratio decreased to 10:1 due to earthworm activity alone and further decreased to 8:1 when inoculated in presence of N + P, showing better influence for the decomposition of a wide C:N ratio material like paddy straw.
The earthworm population was increased by 16-20 times. .
M.K. Jena, P.K. Das and S. Mohanty,Department of Agricultural Chemistry and Soil Science,