HANDLING OF KADIOISOTOPES WITH ANIMALS AND PLANTS 



153 



When soils are used in pots or lysimeters, the radioactive preparation 

 can be thoroughly mixed, distributed throughout the top layer, and 

 applied as a band or in any other way, depending on the information 

 desired. The procedure of Ulrich et al. (45) will illustrate a simple place- 

 ment study with grapevines in the field. A scj[uare ridge of soil 6 to 8 in. 

 high was built 2 ft from the base of each vine. For the surface applica- 

 tion 10 gal of water was added, followed by 5 gal of the P'*' solution ; after 



Fig. 4-24. Diagrammatic view of the peanut plant arranged for study of the indepen- 

 dent root and fruit uptake, showing A, rooting medium, B, fruiting medium, and C, 

 wire-mesh support to prevent the branches and foliage from touching the sand of the 

 fruiting medium. [From Roger W. Bledsoe, C. L. Comar, and H. C. Harris, Absorption 

 of Radioactive Calcium by the Peanut Fruit, Science, 109: 329-330 (1949).] 



the solutions had penetrated the soil, another 25 gal of water was added. 

 For the deep placement a hole 13^^ in. wide and 15 in. deep was drilled in 

 each corner of the sc}uare. The P*^, in about 600 ml of solution, was dis- 

 tributed in equal portions to the four holes around each vine. Immedi- 

 ately thereafter 40 gal of water was added to each vine. 



It is very important that field studies be undertaken with labeled fer- 

 tilizers that are as similar as possible to those commercially available. 

 The method of preparation of radioactive phosphate fertilizers has been 

 described by Hill et al. (46). The U.S. Department of Agriculture 

 Bureau of Plant Industry, Soils, and Agricultural Engineering has devel- 



