HARMFUL EFFECTS OF ALDEHYDES IN SOILS. 7 



The green weights taken at the termination of the experiment were 

 8.5 grams from the control pot and only 4.2 grams from the salicylic 

 aldehyde treated pot, a decrease of approximately 50 per cent. 



In the foregoing salicylic aldehyde has been shown to be harmful 

 to wheat and rice seedlings in distilled water, to wheat, corn, cowpeas, 

 cabbage, and rice in nutrient solutions, and to wheat, corn, and clover 

 in soil in pots. 



EFFECT OF SALICYLIC ALDEHYDE IN SOLUTION CULTURES WITH 

 VARIOUS FERTILIZER INGREDIENTS. 



EFFECT ON WHEAT. 



The effect of salicylic aldehyde on wheat plants was further studied 

 by growing the seedlings in nutrient culture solutions containing the 

 ordinary fertilizer salts, calcium acid phosphate, sodium nitrate, and 

 potassium sulphate. Some of the cultures contained calcium acid 

 phosphate only, some sodium nitrate only, and some potassium sul- 

 phate only. Other solutions were composed of mixtures of two 

 salts, calcium acid phosphate and sodium nitrate, calcium acid phos- 

 phate and potassium sulphate, and sodium nitrate and potassium 

 sulphate. Still other solutions had all three constituents in various 

 proportions. The compositions of the various solutions is given in 

 the first three columns of the tables which are to follow. 1 Two sets 

 of cultures were prepared ; to one set were added merely the nutrient 

 salts; to a similar set 10 parts per million of salicylic aldehyde were 

 added in each culture in addition to the nutrient salts. The culture 

 solutions were changed every three days, four changes being made 

 in the course of the experiment. The solutions were analyzed for 

 nitrates immediately after each change. The phosphate and potas- 

 sium were determined on a composite solution of the four changes. 

 The culture grew from May 15 to May 27, 1912. 



When the plants had grown for several days, it was noticeable that 

 the salicylic aldehyde cultures were developing more slowly. Each 

 of the cultures seemed affected, regardless of the composition or the 

 proportion of the nutrient salts. 



When the plants had grown for 12 days with four changes of the 

 solutions, the green weights were taken. The results obtained with 

 the solution of different fertilizer ingredients are grouped in the tables 

 which follow, so as to bring together those cultures which were com- 

 posed principally of phosphate, those which were composed princi- 

 pally of nitrate, and those composed principally of potassium salt. 

 In each group there were 21 cultures. A fourth group, comprising 

 six cultures, is also given. It includes those cultures with a nearly 

 equal proportion of the three salts. 



1 The solutions were prepared as described in Bui. 70, Bureau of Soils, U. S. Dept. of Agriculture. 



