INTRODUCTION AND METHODS The data ceported here concern the uptake of Co-137 oy plants from soils of Rongelap Atoll, Marshali Islands, with 3pecial reference to fertilization of the and K. culture soil with N, P, The report includes the results of greanhousa pot tasts using Rongelap top soil, as well as foliar analyses of native vegetation growing on the atoll. Rongelap Atoll was contaminated by radioactive fallout on March 1, The principal radionuclide found in plant tissues in 1353 was Cs-137. few inches Radionuclides in the soil remain 1954. 1958 and in the ‘on with 90% or more of che radioactivity in the :ap two inches or less. In the curren: gruenkouse studies, iomaio and squash Diants were grown in Jeattle om top soil (0 to 10 inches) collee¢ted in a coconut grove on Rongelap Island. {perhaps better called soil material) The soil consists entirely of cal- cium carbonate fragments derived from corals anc foraminifera, into which is incorporated about 9% organic matter. In the rather coarse unsieved field soil the pER is 3.0; the cation exchange capacity ia attributable entirely to the organic fraction and is about 8 meq per 100 gm; among the axchangeable cations there are about 80% Ca, soil is coarse, very friable, 15% Mg, 4% Na, and 0.7% K; the and highly porous.