The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, has on many occasions in the past convened a symposium at the World Congress of Soil Science and provided financial support to Congress participants from developing countries. At this 18th World Congress of Soil Science, a workshop rather than a symposium is organized by the Soil and Water Management & Crop Nutrition (SWMCN) sub-programme of the Joint FAO/IAEA Division. The aim of this workshop is to provide a forum for presentation and discussion of scientific and technical advances in FAO/IAEA Member States using nuclear and related techniques to develop optimum soil-water-plant-nutrient management practices to increase crop productivity and foster environmental sustainability. In addition, it provides an excellent opportunity for scientific exchange at a global level, since isotopic techniques are continuously refined and new applications are implemented in crop production and natural resource management. Nuclear and isotopic techniques can be used to track the sources and flows of nutrients and water in soil-plant and soil-plant-animal agro-ecosystems. They therefore help to identify management practices that optimize the efficiency with which natural resources and external inputs are used for crop production. In addition, they can be used to quantify the movement of soil and sediments and associated agrochemicals in the landscape and hence the effects of different management practices on the loss of carbon, sediments, nutrients, and agrochemicals from agro-ecosystems to receiving water bodies. In line with the major theme of the 18th World Congress of Soil Science on Frontiers of Soil Science: Technology and Information Age, the selected applications of nuclear techniques in soil-water-nutrient management as shown in this workshop demonstrate that nuclear techniques provide invaluable tools which can assist to define best management practices for enhancing sustainable crop production, soil and water conservation and environmental protection. Specifically, 26 papers are presented on the use of isotopic techniques to address: (1) Impacts of different land uses on soil organic matter sequestration; (2) Soil erosion and distribution at a catchment scale; (3) Identification of hydrological pathways and impacts of agricultural activities on the transports of soil organic matter, sediments, nutrients and agrochemicals in agricultural landscapes; (4) Water balance and water use efficiency and; (5) Efficiency of fertilizers and crop residues as sources of nutrients for plant growth. Keywords: IAEA, Joint FAO/IAEA Division, nuclear techniques, isotopes, integrated soil management.