Biological nitrogen fixation for sustainable agriculture extended versions of papers presented in the symposium, Role of Biological Nitrogen Fixation in sustainable Agriculture, at the 13th Congress of Soil Science, Kyoto, Japan, 1990 - Ladha, J. K. (Jagdish Kumar), 1952-; George, T. (Thomas), 1958; Bohlool, Behzad Ben; International Congress of Soil Science (13th : 1990 : Kyoto, Japan) (Developments in plant and soil science, 1992)