34 
Journal of Agricultural Research 
Vol. V, No. i 
rnonium carbonate the production of dry matter was stimulated by low 
concentrations of the salts. The growth of plants was not greatly reduced 
by the sulphates even in relatively high concentrations, while with the 
chlorids the yield dropped very rapidly and was practically nothing 
where the concentration was above 4,000 p. p. m. 
Figure 34 shows the dry matter produced by different kinds of crops 
in soils containing sodium chlorid, sodium carbonate, and sodium sulphate 
in concentrations from 1,000 to 10,000 p. p. m. Com gave by far the 
largest quantity of dry matter, but it was probably as much affected by 
the salt as any other crop. The yield was reduced from above 0.6 gm. 
per glass with no salt to less than 0.1 gm. per glass with a concentration 
of 10,000 p. p. m. Canada field peas produced a large quantity of dry 
o 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 
Concentration of salts in p. p. m. 
Tig. 34.—Curve showing the effect of concentration of salts on the dry weight of plants from seeds of various 
kinds. Average for sodium chlorid, sodium carbonate, and sodium sulphate. 
matter, but they were also greatly affected by the concentration of salt. 
Alfalfa gave the least total yield under all conditions. 
The effect of the individual salts on the yield of the various crops is 
brought out in figure 35. The yield of all crops was highest with sodium 
sulphate and lowest with sodium chlorid. With most crops it was only 
about half as great with sodium chlorid as with sodium carbonate. 
DAYS TO COM 3 UP 
During the experiments a count was made each day of the number of 
plants that appeared above the surface of the soil, and from these figures 
a determination was made of the average time required for the plants 
in each glass to come up. The average results are in some cases mis¬ 
leading, because with toxic salts no plants germinated in the high con¬ 
centration, and the averages were determined from the plants that came 
