AGRICULTURAL HANDBOOK 395, tJ.S. DEPT. OF AGRICULTURE 



often constitute tlie main hazard, we evaluated 

 the effectiveness of some treatments by the re- 

 duction in uptake of radiostrontium. 



This bulletin describes the effectiveness and 

 feasibility of many possible treatments of con- 



taminated land under various soil and crop con- 

 ditions. This information should allow one to 

 choose a suitable treatment after the objectives 

 have been decided upon. This decision must take 

 into account the particular circmnstances of each 

 instance of contamination. 



REVIEW OF RESEARCH 



There is widely scattered literature concerning 

 the treatment of radioactive contamination on 

 land. Some of the publications are not generally 

 available, and many of the pertinent results have 

 not been considered in relation to agricultural 

 areas. In this review, we have attempted to or- 

 ganize information about a wide variety of pro- 

 posed treatments for contaminated agricultural 

 land. References are either to original work or to 

 critical reviews. The literature citations are se- 

 lected to give pertinent results for various treat- 

 ments. 



The general problem of managing contaminated 

 agricultui-al land has been discussed briefly in 

 a previous publication (-5i). Experimental results 

 tliat were available in 1963 concerning the re- 

 moval of crops, crop residues, and surface soil, 

 tlie deep placement of contaminated soil, and the 

 application of fertilizei-s and soil amendments 

 were reviewed. A Russian review of the problem 

 has been translated and is available from the U.S. 

 Department of Commerce (1). It discusses re- 

 sults with deep plowing, leaching, and the ap- 

 plication of lime and fertilizer. 



Many tests on the decontamination of land 

 areas that have been conducted by the U.S. De- 

 partment of Defense are relevant to agricultural 

 decontamination. A performance summary of 

 these tests has been published (^9), and the ap- 

 plication of the results in areas contaminated by 

 fallout lias been considered (25). These tests are 

 particularly valuable for including techniques 

 of snow removal and the decontamination of 

 frozen and thawing soil that have not been stud- 

 ied elsewhere. 



Removal of Crops and Crop Residues 



A number of tests on the remo\-al of contam- 

 inated crops and crop residues have been made 

 by the Agricultural Research Service at Belts- 



ville, Md. (18, 21, 22). Radioactive material was 

 applied as a spray or as simulated dry fallout. 

 Measurements were made of the amount of radio- 

 active material removed as various crops or crop 

 residues were removed from the land. The tests 

 included removal of standing crops at various 

 stages of maturity, removal of sod, and removal 

 of grass or straw mulch. 



Removal of standing crops from a contami- 

 nated area removed only part of the radioactive 

 material, because much of it fell through the 

 vegetative cover to the ground. From one-fourth 

 to one-half of the radioactive material was us- 

 ually carried on green crops removed by con- 

 ventional types of forage-harvesting machinery 

 (21, 22). These included a flail-type forage chop- 

 per, a direct-cut forage harvester, and a mower, 

 followed by a side-delivery rake and windrow 

 pick-up baler. Crops removed by the forage chop- 

 per and harvester carried somewhat more con- 

 tamination than those removed by mowing, rak- 

 ing, and baling. Crops providing more complete 

 ground cover usually carried more of the radio- 

 active material when they were removed. ^\Tien 

 rain fell or sprinkler irrigation was used after 

 contamination and before crop removal, the 

 amounts of contamination removed with the crops 

 were appreciably lower. 



Harvester-thresher combines were used for har- 

 vesting and threshing mature rye and soybeans. 

 About one-tenth of the contamination was re- 

 moved with the straw. The harvested grains con- 

 tained less than 1 percent of the contamination 

 in rye and less than 0.1 percent in soybeans (18). 

 In these experiments, the radioactive material 

 was carried on tiny glass spheres (20^0 fi in 

 diam.) in order to simulate fallout occurring 

 under dry conditions. 



Cutting and removing sod removed more than 

 90 percent of radioactive contamination pre^d- 

 ously sprayed on the surface. The high effective- 



