Oct. 4, 1915 
Effect of Alkali Salts in Soils on Crops . 
49 
makes it impossible to say exactly what are the practical limits of 
alkalies. 
In getting the limits given below it was considered that when alkali 
retarded germination and growth to about half what they were in soils 
without alkali the practical limit had been reached. Certainly it would 
not be profitable to use a soil where alkali decreased yields below half 
normal. 
Figures 46 and 47 show the practical limits of growth of wheat in 
loam and sand for 13 different salts. It will be noted that these salts 
bear a similar relation to each other in both kinds of soil, although only 
about half as much alkali is required in sand to reach the toxic limit as 
in loam. One of the most striking features about the diagram is the 
fact that in sand the carbonates are proportionately more toxic when 
compared with other salts than they are in loam. 
1 
Fiq. 46.—Diagram showing the percentage of alkali salt in loam soil giving about half normal germination 
and production of dry matter in wheat. 
Foam having 0.3 per cent and sand having 0.2 per cent of sodium 
chlorid contain a limit of this salt for the profitable production of crops. 
The other chlorids may be somewhat higher, while the nitrates may be 
about 0.1 per cent higher than the chlorids. On loam crops grow well 
with as high as 1 per cent of the sulphates, while in sand from 0.5 to 
0.7 per cent of the sulphates is injurious. 
Figure 48 gives a comparison of the resistance of barley, oats, wheat, 
alfalfa, sugar beets, com, and Canada field peas for sodium chlorid, 
sodium carbonate, and sodium sulphate in loam. Barley can withstand 
0.5 per cent of sodium chlorid, 1 per cent of sodium carbonate, and more 
than 1 per cent of sodium sulphate. All crops in the test except oats, 
sugar beets, com, and field peas produced more than half normal growth 
where 1 per cent of sodium sulphate was present. There was a great 
difference in the resistance of various crops to sodium carbonate, the 
