MINERAL COMPOSITION OF CROPS 17 



"Alkali Disease" or Selenium Poisoning 



In 1934, as a result of a preliminary field survey of " alkali disease," 

 Franke and coworkers (197) concluded that 



Soil seems to be an important factor in the occurrence of this diseased condition 

 of livestock. Every case investigated occurred on certain soils that were called 

 Pierre clay or Pierre clay loam, or could be attributed to grain or hay grown on 

 such soils. These soils have developed from the geological formation known as 

 Pierre shale. 



It hardly seems necessary to discuss extensively in this report 

 alkali disease, or what is now known to be selenium poisoning, inas- 

 much as such complete summaries as those of Byers (100, 101, 104) 

 and Moxon (419) are available and well known. It is sufficient to 

 state that the disease is closely related to certain soils, and that the 

 work of identifying these soils and the relative toxicity of their 

 selenium contents has now practically been completed by Byers and 

 his coworkers in the Division of Soil Chemistry and Physics of the 

 Bureau of Plant Industry. A brief discussion of their work with 

 plants and soils will be presented in later sections. 



Iodine 



Probably the first reference to the relationship of goiter to iodine 

 deficiency in soils is that of Chatin (11.2), who in 1851 observed that the 



air is less iodized in the Alps than in Paris; the same is true of the rain waters. 

 The iodine content of tillable soil and its products is also higher than in the countries 

 where goiter is more prevalent. 



Chatin offered no data to substantiate his statements. 



Many investigations have been made of the iodine content of foods 

 grown in goitrous regions and in goiter-free regions (3, 45, 174, 175, 

 265, 363, 445, 548) , but only those dealing with actual soil conditions 

 will be discussed here. 



Von Fellenberg (176) in 1924 reported that the soil at Effingen, 

 Switzerland, a goiter-free area, contained 11.9 p. p. m. of iodine, 

 while that at Hunzenschwill, where 56.2 percent of the populations 

 suffered from goiter, contained 0.620 p. p. m. of iodine. 



Goiter is reported to be quite prevalent in New Zealand, and "its 

 incidence is in general roughly inversely proportional to the average 

 iodine in the soil," according to Hercus and others (264)- Hopkirk 

 and coworkers (277) showed in 1930 that the iodine content of soils 

 in a certain goitrous region of New Zealand varied from a few parts 

 up to 900 parts in 10 million. They found little correlation between 

 the iodine contents of the soil and those of pastures grown on them. 

 They state that, generally speaking, alkaline soils do not give up 

 iodine to plants, while acid soils do so ver}^ readily. They found, 

 however, that cows' milk from the goiter-free regions contained three 

 time as much iodine as did that from affected regions. 



Sykes (547) reported that limestone regions in particular were 

 characterized by complete absence of goiter. Aston in 1930 reported 

 the soil in a goiter region to be low in iodine (33). He made the 



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