A COMPARISON OF SALT REQUIREMENTS FOR YOUNG 
AND FOR MATURE BUCKWHEAT PLANTS IN 
WATER CULTURES AND SAND CULTURES 
John W. Shive and William H. Martin 
In recent experimental work^ bearing on the growth of plants in 
nutrient solutions, it has been demonstrated that the three salts, 
mono-potassium phosphate, calcium nitrate, and magnesium sulphate, 
in the proper proportions, in solutions of suitable concentrations, 
furnish a medium very well adapted to general culture work. This 
three-salt solution produces excellent growth and has the additional 
advantage of being the simplest nutrient solution (with respect to the 
number of salts employed) which can be devised and still contain all 
the elements, except iron, essential for plant growth. To determine 
approximately the optimum salt proportions for wheat {Triticum 
vulgare) during the first four weeks after germination, and for buck- 
wheat (Fagopyrum esculentum Moench) during the early period of 
growth from germination to flowering, an optimal series of 36 different 
solutions was employed. All the solutions had approximately the 
same total osmotic concentration value of 1.75 atmospheres, and the 
salts were so distributed as to include all possible sets of salt propor- 
tions, when the partial concentrations of the three components were 
made to vary by increments equal to one tenth of the total concentra- 
tion. Each solution contained the usual trace of iron as ferric phos- 
phate, in addition to the three salts. Tests of the 36 different pro- 
portions of the nutrient salts showed that the best growth of wheat 
tops was produced by a solution containing the three salts in the fol- 
lowing volume-molecular proportions: KH2 PO4, 0.0180 m.; Ca(N03)2, 
0.0052 m.; and MgS04, 0.0150 m. The best growth of buckwheat 
tops and of roots was obtained in a solution in which the partial volume- 
molecular concentrations of the three salts were: KH2PO4, 0.0144 m.; 
Ca(N03)2, 0.0052 m.; and MgSOd, 0.0200 m. 
These proportions of the three salts are, of course, to be considered 
^ Shive, J. W. A three-salt nutrient solution for plants. Amer. Journ. Bot. 4: 
157-160. 1915. 
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