15. Role of Vermicomposting in Agricultural Waste Management

Agricultural wastes including food processing wastes are the by-products of various food industries that have not been recycled or utilized for other purposes. These agri-horticultural wastes constitute a big problem in municipal landfills due to their high rate of biodegradability. In other words, they are actually the unutilized raw materials whose industrial applications are less than their cost of collection and recovery; and therefore they are generally considered as wastes. The major agricultural sources are livestock, crop residues, tree wastes, aquatic weeds, agro-industrial byproducts, marine wastes and tank silt. The advancement of agricultural biotechnology has led to the development of high yielding variety crops and their subsequent crop residues such as straw, leaves twigs, stubbles along with huge amounts of grasses and weeds. During vermicomposting, stabilization of organic waste occurs through the joint activity of earthworms and aerobic micro-organisms. Vermicomposting is ecofriendly and an economic technique for management of agricultural waste. The earthworm Eisenia foetida is one of the most common species used in vermicomposting. The temperature of the earthworm feed should be in the range of 20–35 °C along with relative humidity between 60–80%. Commonly known as farmer’s friends, the earthworms improves the fertility of the soil by decomposition of organic matter. In this process, the earthworms leave behind their castings that are exceptionally a rich source of bio-fertilizer. Physico-chemical analysis had shown that vermicomposting decreases total organic carbon (TOC) and carbon-nitrogen (C/N) ratio but increases nitrogen-phosphorus-potassium (NPK) content when compared to compost and other agricultural wastes. The other areas of its application are for crop improvement through pathogen destruction (biocontrol), improving the water holding capacity of soil and production of plant growth regulators. All these factors will ultimately lead to improved crop growth and yield, and better soil physical, chemical and biological properties.