Isotope and radiation techniques in soil physics and irragation studies 1973 : proceedings of a Symposium on Isotope and Radiation Techniques in Studies of Soil Physics, Irragation and Drainage in Relation to Crop Production jointly organized by the International Atomic Energy Agency and the Food and Agriculture Organization of the United Nations, and held in Vienna, 1-5 October 1973. (Proceedings series, 1974)