92 TRANSACTIONS OF THE 
_ especially sodium chloride and mixed salts, apparently 
stimulated the production of spikelets. 
For the sand soil the salts did not seem quite so 
toxic to the plants at a given concentration and time as 
did the loam. This was perhaps due to a larger propor- 
tion of free water in the sand; both soils containing 20 
per cent of water but loam holding it more strongly. 
Sand soil withstood up to 1,000 parts per million of sodium 
carbonate water for two to three years without a great 
reduction in the production of wheat. This strength of 
solution reduced the crop to less than one-half for the 
fourth year. Water containing 1,000 parts per million 
or more of any of the alkali salts when applied as needed 
by the plants to an undrained sandy soil made it too 
toxic for grain production in three to four years. Pro- 
duction was not greatly decreased by sodium sulphate 
until a solution with a strength of 4,000 parts per mil- 
lion was used. 
Alkali irrigation water appears to influence plant 
production only so far as it increases the strength of the 
soil solution above a point tolerated by plants. More 
salts than are ordinarily considered harmful were with- 
stood in this experiment before fatal strengths were 
reached. This was perhaps because the soil was kept 
high in moisture by weekly irrigation. 
In another experiment water containing sodium 
carbonate proved more injurious to wheat plants after 
they had reached the five-leaf stage than the other alkali 
salts. Both sodium chloride and sodium sulphate stimu- 
lated dry matter production up to a certain concentra- 
tion even when the soil contained many times the quantity 
ordinarily harmful. When watered with an alkali solu- 
tion after reaching the five-leaf stage of growth sodium 
chloride caused the plants to produce dry matter with less 
water than did other treatments. Wheat growing on 
alkali free soil was retarded in growth in a single season 
by water containing as much as 10,000 parts per million 
of sodium carbonate but 25,000 parts per million of sodium 
chloride and much more than this of sodium sulphate 
was endured by plants which were past the five-leaf 
stage. Wheat appears to be many times more sensitive 
