GRAIN CROPS 



211 



nent salt the quantity was much less. Observations by 

 Shutt and Smith (26) show that on a loam soil with a 

 heavy clay subsoil, wheat made a gdod growth where the 

 upper six inches of soil contained practically no alkali 

 salts, but the next foot contained 1780 parts per million, 

 and below this over 8000 parts per million of salts most 

 of which was sodium sulphate. When the upper six 

 inches contained 1230 parts per million of salts and the 



FIG. 31. ALKALI SPOT IN A GRAIN FIELD. 



soil beneath this 7000 parts per million the growth was 

 poor, apparently showing that the upper six inches of soil 

 was the injurious portion. In the Bear River Valley, 

 Utah, Jensen and Strahorn (16) found wheat doing well 

 in a soil the top foot of which contained 5000 to 5600 parts 

 per million of alkali, mostly sodium chloride. Lough- 

 ridge (19) places the limits for unaffected growth at 1520 

 parts per million total salts for Gluten wheat and 1080 for 

 ordinary wheat. 



For sodium carbonate Headden (8) states that 400 parts 

 ner million. in the soil will prove injurious to wheat, while 



