“Agricultural Microbiology” Treatise compiled by collecting and digesting the pertinent information published in various books and review papers to assist graduate and postgraduate students for various competitive examinations like JRF, NET, ARS conducted by ICAR. It is mainly helpful for students for getting an in-depth knowledge in Agricultural Microbiology. The book combines the basic concepts, keynotes in Microbiology other applied aspects of microbiology. This book mainly designed to provoke individual thought and critical examination of their memory to retain the conceptual ideas of the Agricultural microbiology subject. There would be a continuous effort on the part of the authors to revise, update and modify the contents of the book. The authors are deeply thankful to individuals, who helped on time for the successful preparation of this book.