HARMFUL EFFECTS OF ALDEHYDES IN SOILS. 3 



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 ^ 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 com in nutrient solutions of calcium acid phos- 

 phate, sodium nitrate, and potassium sulphate. 



No. 



Treatment. 



Green 

 weight. 



Relative 

 growth. 



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. 



Gram. 

 1.00 

 .60 

 .60 

 .21 

 .21 

 .10 



100 

 60 

 60 

 21 

 21 

 10 



See especially Bui. 70, Bureau of Soils, U. S. Dept. of Agriculture. 



