Introduction: Perspectives and General Concept of Irrigation -- Fundamentals of Irrigation Development and Planning -- Weather: A Driving Force in Determining Irrigation Demand -- Soil: A Media for Plant Growth -- Plant: A Machinery of Water Absorption -- Water: An Element of Irrigation -- Field Water Balance -- Soil-Water-Plant-Atmosphere Relationship -- Crop Water Requirement and Irrigation Scheduling -- Measurement of Irrigation Water -- Water Conservation and Harvesting -- Economics in Irrigation Management and Project Evaluation. The book "Fundamentals of Irrigation and On-farm Water Management" (Volume 1) is a true textbook for the undergraduate students in Bio-Science Engineering, Agricultural Engineering, Water Resource Engineering, Civil & Environmental Engineering, Biological Systems Engineering, Environmental Science, Biological Sciences and Agricultural Sciences. The book deals with the fundamental aspects of irrigation development, climatic impact on crop production, irrigation requirement estimation, scheduling of irrigation, water measurement, water conservation & harvesting, and economic aspects of irrigation management. Understanding these processes leads to more rational and cost-effective decisions regarding irrigation planning, designing, and implementing irrigation & on-farm water management programs and projects, maintenance practices to maximize performance and reliability. The book's objective is to present the fundamental principles of irrigation need assessment, water relations in the soil-plant-atmosphere continuum, and the principles needed to adopt the most appropriate approach toward irrigation development and management. The book presents the factors affecting the phenomena/parameter related to irrigation, exploring the relationship of irrigation need to the relevant factors, laboratory and field measurement procedures of their measurement (principles, background theory, and detail working methods). The content of this book provides the foundation to develop more appropriate irrigation design, and irrigation & water management. The book is equally useful for postgraduate students, engineers/practitioners and scientists in the relevant fields.