90 TRANSACTIONS OF THE 
ered with paraffine paper as soon as the plants were up. 
Field studies are often complicated because of varying 
moisture conditions in the soil. In these experiments 
the moisture was maintained at 20 per cent of the dry 
weight of the soil in both the loam and the sand by adding 
the alkali solutions to the plants as fast as they used the 
water. The crop in all cases was wheat; wheat being 
more easily handled and studied than most other crops 
and its action under alkali conditions having been more 
carefully studied. Low concentrations of the various 
solutions were not used as this would have prolonged too 
greatly the experiment. The same conditions. result 
from running the experiment with stronger solutions. It 
is the quantity of injurious salts in the soil less the quan- 
tity held in an insoluble form which determines the tox- 
icity to the plant. The conditions reached in the four 
years of the experiment with a given strength of solution 
could have been obtained in double this length of time 
with half the strength. The results are applicable to 
field conditions only where the soil is impervious or nearly 
so. Also where the moisture conditions of the soil are 
different from those of the experiment an allowance 
should be made accordingly. 
To learn which parts of the plant are affected by 
the alkali, studies were made of the dry weight of the 
plant, the number of leaves produced per plant and their 
length, the number of culms and their length, the number 
of heads, and the number of spikelets per head. The 
following conclusions have been drawn from the experi- 
ments: . 
As a general rule, the dry weight of the plants indi- 
cated the action of the alkali better than the other deter- 
minations. However, as the number of leaves per plant, 
the length of culms, and the number of heads produced 
were affected much the same as the dry weight, these 
factors might be used roughly to estimate the toxicity of 
alkali soil. When the conditions were unfavorable to 
high production of dry matter so that variation in pro- 
duction was not large between the different treatments, 
certain of the factors other than dry matter indicated 
the quantity of salts in the soil better than did the weight 
of the plants. 
