HARMFUL EFFECTS OF ALDEHYDES IN SOILS. 6 
in soils in pots, and finally in the field. For these further studies, 
which required quantities impossible of procuring from the soil 
itself, the chemically prepared salicylic aldehyde was used. 
EFFECT OF SALICYLIC ALDEHYDE ON PLANTS IN SOLUTION CULTURES. 
EFFECT ON WHEAT. 
The method of growing wheat seedlings in solution cultures is fully 
described in previous bulletins. 1 
Salicylic aldehyde was used in amounts of 10, 25, 50, 100, and 200 
parts per million dissolved in pure distilled water. A culture of dis- 
tilled water without salicylic aldehyde was included in the test and 
used as a control. The cultures grew from May 4 to May 16, 1912. 
It became at once apparent that the salicylic aldehyde was very 
harmful to the seedling wheat, even in the lowest concentration of 
10 parts per million. The appearance of the series of plants on the 
sixth day is shown in Plate I, figure 2. In the culture solution con- 
taining 10 parts per million growth was reduced 31 per cent; in the 
25 parts per million solution growth was reduced 69 per cent; with 
50, 100, and 200 parts per million the plants were killed. 
EFFECT ON CORN. 
The effect of salicylic aldehyde on corn plants was tested by grow- 
ing the corn in nutrient solutions of calcium acid phosphate, sodium 
nitrate, and potassium sulphate, with and without salicylic aldehyde. 
The aldehyde was used in amounts of 10, 25, 100, and 200 parts 
per million. One corn plant was used in each culture jar containing 
250 c. c. of the solution. The plants were germinated and put in the 
solution when they were about 1 J inches high. The corn grew in the 
solutions from May 26 to June 20, 1912. A photograph of the cul- 
tures, taken when the plants had been growing for 10 days, is shown 
in Plate II, figure 1. The harmfulness of this substance to corn is 
clearly shown. The effect was very noticeable, even in the culture 
containing 10 parts per million. In the culture containing 200 parts 
per million there was very little growth; the plants were almost dead. 
In Table I are given the green weights of the plants, taken when 
the experiment was concluded. The last column indicates the rela- 
tive growth. 
Table I. — Effect of salicylic aldehyde on corn in nutrient solutions of calcium acid phos- 
phate, sodium nitrate, and potassium sulphate. 
No. 
Treatment. 
Green 
Relative 
weight. 
growth. 
Gram. 
1.00 
100 
.60 
60 
.60 
60 
.21 
21 
.21 
21 
.10 
10 
Nutrient solution 
Same + 10 parts per million salicylic aldehyde. . 
Same + 25 parts per million salicylic aldehyde. . 
Same + 50 parts per million salicylic aldehyde. . 
Same + 100 parts per million salicylic aldehyde. 
Same + 200 parts per million salicylic aldehyde. 
See especially Bui. 70, Bureau of Soils, U. S. Dept. of Agriculture. 
