This bulletin (1) defines exchangeable sodium; (2) describes the effects of exchangeable sodium on soil properties and the growth of plants; (3) gives the relative tolerance of some crops to exchangeable sodium; (4) and explains how crop growth can be improved on sodic soils.

This bulletin explains how soil salinity affects field crops, provides information on the salt tolerance of field crops, and tells how to manage crops on saline soils.

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.

Origin,classification and distribution of salt-affected soils;saline soils and their management;sodic soils and their management;salinity problems of the dryland regions;water quality and crop production;socio-economic considerations in reclamation and management of salt-affectedsoils;

Salinity tolerance in plants is a complex problem encompassing numerous morphological, physiological and biochemical processes and adaptations at the cellular, sub-cellular and whole plant levels. The book comprising eleven chapters deals with diverse aspects of salt tolerance including plant response to salinity and sodicity, crop tolerance at different growth stages and criteria for evaluating the same. The mechanism of salt injury viz. osmotic, ionic and nutrient imbalance has been dealt with, adopting an integrated appraoch. Likewise, the recent information on photosynthesis, respiration, carbohydrate, nitrogen and protein metabolism, enzyme dynamics and plant hormones, as well as nodulation and symbiotic nitrogen fixation in legumes has been elaborated comprehensively. Special attention has been given to the interaction between essential nutrients and salinity as it is vital for alleviation of adverse effects of salt stress. The synthesis of knowledge on different mechanisms of salt resistance, including osmoregulation with organic and inorganic solutes has also been presented. Various methods of introducing salt tolerance in plants such as breeding, genetic variations, physiological approaches, tissue culture, somaclonal variation, somatic hybridation and recombinat DNA technology have been discussed. The nature and properties of salt affected soils and groundwaters and principles for amelioration and management of these critical problems have been included in this book. Furthermore, Afforestation and Agroforestry techniques for salt affected soils with emphasis on salt tolerant tree species and suitable tree crop combinations also find their much needed due space in the present book.