SELENIUM — HURD-KAKRER 



293 



Table 1. — Quantities of selenium taken up by ivheat plants from sodium selenate 

 added to soil. [Figures are parts per million of air-dry tveights)^ 



A. IN KEYPORT CLAY LOAM (VIRGINIA) 



B. IN PIERRE CLAY (SOUTH DAKOTA) 



I Analyses by A. Van Kleeck under the direction of Dr. H. O. Byers, U. S. Bureau of Chemistry and 

 Soils. The dilTerence in absorption of selenium from the two kinds of soil is discussed in an earlier publi 

 cation (Hurd-Karrer, 1935). 



Table 2. — Quantities of selenium (as parts per million on an air-dry basis) 

 taken up by different kinds of a^imial crop plants from greenhouse plots 

 treated with 5 parts of selenium (as sodium selenate) per million of soiV 

 None of the plants showed selenium injury 



» Analyses by A. Van Kleeck under the direction of Dr. H. Q. Byers, U. S. Bureau of Chemistry and 

 Soils. 



Young wheat plants contain at least five times as miicli selenium 

 per unit of dry matter as old ones, and leaves contain more than 

 the stems and grain. Thus severely injured wheat plants grown with 

 30 parts per million selenium (as sodium selenate) added to the soil 

 contained 1,120 parts per million when they were sampled at an 

 early stage of development and but 220 parts per million at ma- 

 turity. Similarly grown plants with 260 parts per million in their 

 leaves at maturity had but 70 in the stems and 150 in the little grain 

 that developed. Wheat grown in white sand cultures with nutrient 

 solutions to which was added enough selenium (as sodium selenate) 

 to produce a concentration of only 1 part in a million (by weight 

 of sand) contained 330 parts per million (by weight of their air-dry 

 tissues) after growing 1 month. Some of the plants were allowed 

 to mature. The leaves then contained only 40 parts per million, 

 the stems 12 parts per million, and the grain 8 parts per million. 



