which have been observed for samples collected from the aged fallout areas where conditions encouraged resuspension and surface contamination. INTRODUCTION Two important mechanisms of incorporation are involved in the vegetation transport of radionuclides from contaminated soil to grazing animals. Findings in earlier progress reports (Romney et al., 1974; 1975) indicate that superfi- cial entrapment of resuspendable material on plant foliage is probably the most important process whereby vegetation becomes contaminated with Pu and Am radionuclides in aged fallout areas on the Nevada Test Site and the Tonopah Test Range. The other process of incorporation by root uptake is difficult to assess under natural conditions involving resuspension. Therefore, samples of soil were removed from the aged fallout areas and used in pot culture experi- Ments to test for root uptake under glasshouse conditions where foliage contamination could be prevented with confidence. This interim report contains data on the uptake of 239°240py and 24 am through roots of alfalfa, barley, and soybean plants from experiments designed to test the effects of nitrogen fertilizer, acidulation, and organic matter amendments with and without additions of diethylenetriaminepentaacetic acid (DTPA). This chelating agent has the ability to increase uptake by plants through roots of several metals and is widely used as a practical means of correcting iron deficiency in plants. It has been shown to greatly increase the uptake from soil of 2tlam by plants (Wallace, 1972). Another motivation for testing the ability of chelating agents to modify plant uptake of Pu and Am radionuclides stems from their wide use in chemical processing and storage of transuranic elements. MATERIALS AND METHODS Soil was collected from stratum 3 of the Area 13 fallout area (Gilbert and Eberhardt, 1974) for use in experiments to investigate the effects of soil amendments on plant uptake of 2339240by and 24am with and without additions of DTPA chelate. The experimental design involved three sets, each containing four soil amendments with and without DTPA, in triplicate (3 sets x 4 amendments x 2 DIPA x 3 replicates = 72 pots). Soil collected from the field was subdivided into twelve 20 kg lots and mixed thoroughly with given amendments in a P-K blender for one hour before subdividing into six 3200-g lots for potting. An 800-g sample of soil from each mixing was submitted to the contract laboratory for radiochemical analysis. The soil amendments consisted of a control soil treatment (unmodified except for mixing), nitrogen fertilization (applied as 54