This book highlights various sources of organic and biological agents which can be used for organic farming and as well as for maintenance of soil fertility over years.The potential, technology and uses of different types of organic sources such as animal wastes, biogas slurry, poultry and sea food wastes; agricultural, tree and urban wastes; wastes from agro-industries such as oil cakes, sugar industry byproducts, canning and food processing, fermentation and tannery wastes have been highlighted. The characteristic, potential and use of rock phosphate, basic slag and flyash have also been covered. It coverstheconcepts of organic Agriculture, scientific basis and technologies for composting oforganic wastes and the underground biodiversity as basis for biofertilizersin 21 chapters and which would be useful to farmers, students, extension workers and scientists.