EFFECT OF SODIUM SALTS IN WATER CULTURES ON 
THE ABSORPTION OF PLANT FOOD BY WHEAT 
SEEDLINGS 
By J. F. BreazealE, 
Laboratory Assistant , Biophysical Investigations , Bureau of Plant Industry 
INTRODUCTION 
The following experiments were undertaken to determine the extent 
to which the presence of the various sodium salts commonly found in 
alkali soils affects the absorption of plant-food elements by wheat seed¬ 
lings. Sodium chlorid, sodium sulphate, and sodium carbonate in con¬ 
centrations ranging from 50 to 1,000 p. p. m. 1 were employed in connec¬ 
tion with a standard nutrient solution, consisting of 200 p. p. m. of N 0 3 
as sodium nitrate, 200 p. p. m. of K 2 0 as potassium chlorid, and 130 p. p. m. 
of P 2 0 5 as sodium phosphate, together with calcium carbonate (CaC 0 3 ) in 
excess. The same variety of hard wheat, Minnesota Bluestem C. I. 169 
(Triticum vulgare ), was used in all the measurements. 
CULTURE METHOD 
The enameled culture pans each contained 2,500 c. c. of the nutrient 
solution. Each pan was provided with a perforated aluminum disk, sup¬ 
ported on sealed glass buoys, so as to float at the surface of the solution. 
Wheat seeds were sprinkled over the disks in numbers sufficient to pro¬ 
vide about 1,000 seedlings in each pan. 
The nutrient solution in each pan was changed every two days and 
during the intervening period was kept approximately at the original vol¬ 
ume by the addition of water. The analyses showed that with this 
method of procedure there was always an abundance of plant food at the 
disposal of the seedlings. 
During the first two days of the experiment the seedlings were grown 
in the nutrient solution alone. At the end of the second day sodium 
chlorid, sodium sulphate, and sodium carbonate were added to the nutri¬ 
ent solution in concentrations varying from 50 to 1,000 p. p. m., as shown 
in Tables I to IV. The sodium carbonate in the lower concentrations 
gradually changed to sodium bicarbonate, owing to the absorption of 
carbon dioxid from the atmosphere and to its evolution fronj the roots of 
the growing seedlings. Where the original concentration was 300 p. p. m. 
and above, sodium carbonate was still present after the plants had been 
grown in the culture solution for two days. 
1 Parts per million in solution by weight. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
gh 
(407) 
yoi. vn, No. 9 
Nov. 27,1916 
G—100 
