Human-induced salinisation is a major threat to the world's land and water resources. Inadequate development of irrigation projects, inefficient irrigation, lack of proper drainage, and environmental mismanagement such as the clearing of native vegetation, are responsible for the loss of millions of hectares of agricultural and grazing land, as well as the misuse of scarce water resources. The first part of this book analyses the problem in the context of the world's population, its climate and its land and water resources. It reviews irrigation methods and crop water requirements, the processes of salinisation, and its management. The second part describes irrigated land, dryland and water-resource salinity problems in 11 countries, which contain approximately 70 per cent of the world's irrigated land. In each case study, background data, environmental conditions and past management practices are given to provide an understanding of why salinity occurs in particular places, and of the management methods employed against it.

This open access book is an outcome of the collaboration between the Soil and Water Management & Crop Nutrition Section, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Department of Nuclear Sciences and Applications, International Atomic Energy Agency (IAEA), Vienna, Austria, and Dr. Shabbir A Shahid, Senior Salinity Management Expert, Freelancer based in United Arab Emirates.The objective of this book is to develop protocols for salinity and sodicity assessment and develop mitigation and adaptation measures to use saline and sodic soils sustainably. The focus is on important issues related to salinity and sodicity and to describe these in an easy and user friendly way. The information has been compiled from the latest published literature and from the authors’ publications specific to the subject matter. The book consists of six chapters. Chapter 1 introduces the terms salinity and sodicity and describes various salinity classification systems commonly used around the world. Chapter 2 reviews global distribution of salinization and socioeconomic aspects related to salinity and crop production. Chapters 3 covers comprehensively salinity and sodicity adaptation and mitigation options including physical, chemical, hydrological and biological methods. Chapter 4 discusses the efforts that have been made to demonstrate the development of soil salinity zones under different irrigation systems. Chapter 5 discusses the quality of irrigation water, boron toxicity and relative tolerance to boron, the effects of chlorides on crops. Chapter 6 introduces the role of nuclear techniques in saline agriculture.

The papers assembled here cover topics such as technological advances in soil salinity mapping and monitoring, management and reclamation of salt-affected soils, use of marginal quality water for crop production, salt-tolerance mechanisms in plants, biosaline agriculture and agroforestry, microbiological interventions for marginal soils, opportunities and challenges in using marginal waters, and soil and water management in irrigated agriculture.

Approximately half of the irrigated area of Iran falls under different types of salt-affected soils and average yield losses may be as high as 50 percent. Slightly and moderately salt-affected soils are mostly found on the piedmonts at the foot of the Elburz (Alborz) Mountains in the northern part of the country. The soils having severe to extreme salinity are predominantly located in the Central Plateau, the Khuzestan and Southern Coastal Plains and the Caspian Coastal Plain. The process of salinization of the surface water resources is mainly due to natural conditions, and to a lesser extent, to the discharge of drainage water into the river systems. Estimates show that about 6.7 km3 of brackish water flow annually through 12 major rivers. There is no straightforward solution to the complex problems of salt-induced soil and water resources degradation in Iran. The approaches addressing the management of these resources need to be multidimensional and must take into account biophysical and environmental conditions of the target areas as well as livelihood aspects of the associated communities.

The salinity problem in irrigation:an introductory review; evaluation and classification of water quality for irrigation;effescts of salinity and soil water regime on crop yelds; irrigation and soil salinity; fertilization and salinity;impact of irrigation on the quality of groundwater and river flows; economic evaluation of irrigation with saline water withim the framework of farm,Economic impacts of regional economic effects of changes in irrigation water salinity within a river basin framework; the case of the colorado river.

ThisThis report discusses the nature and causes of secondary salinization, reviews strategies developed and tested within IBIS to mitigate salinization, and identifies areas requiring further investigation.