HARMFUL EFFECTS OF ALDEHYDES IN" SOILS. 5 



photograph of the cultures was taken when they had grown seven 

 days, and is shown in Plate III, figure 1. Growth was materially 

 reduced by 10 and 25 parts per million, while 50, 100, and 200 parts 

 per million killed the plants. Cultures stronger than 50 parts per 

 million are not shown. 



When weighed at the termination of the experiment, growth in the 

 culture containing 10 parts per million salicylic aldehyde was found 

 to be reduced 39 per cent. With 25 parts per million growth was 

 reduced 61 per cent. This shows that the aldelryde in small amounts 

 was quite harmful to the young cabbage plants. 



EFFECT ON RICE. 



When tested on rice seedlings in water and in nutrient solutions 

 the salicylic aldehyde was found to be harmful to this crop also. The 

 distilled water solutions of 10 parts per million of salicylic aldehyde 

 gave a depression of 16 per cent in the green weight of the plants. 

 In the nutrient solutions the 10 parts per million of salicylic aldehyde 

 gave a depression of 15 per cent in the green weight. 



EFFECT OF SALICYLIC ALDEHYDE IN SOIL IN POTS. 



EFFECT ON WHEAT. 



Experiments were made to study the effect of salicylic aldehyde in 

 soil. Paraffined wire pots 1 holding approximately 1 pound of soil 

 were used. The soil was a heavy clay loam. Before potting, por- 

 tions of the soil were treated with varying amounts of salicylic 

 aldehyde. Six wheat plants were grown in each pot. The experi- 

 ment was begun May 27 and discontinued June 18. In Plate III, 

 figure 2, are shown the plants as they appeared near the end of the 

 experiment. This shows that the salicylic aldehyde was harmful. 

 The final results are given in Table III. 



Table III. — Effect of salicylic aldehyde on wheat plants in soil. 



No. 



Treatment. 



Green 



Relative 



weight. 



growth. 



Gram. 





0. 6.5 



100 



.65 



100 



.50 



77 



.40 



61 



Dead.... 





Dead.... 





Clay loam untreated 



Same + 10 parts per million salicylic aldehyde. 

 Same 4- 25 parts per million salicylic aldehyde. 

 Same + 50 parts per million salicylic aldehyde. 

 Same + 100 parts per million salicylic aldehyde 

 Same -j- 200 parts per million salicylic aldehyde 



As seen from the table the aldehyde in amounts of 10 parts per 

 million in the soil had no effect. Larger amounts than 10 parts per 

 million were quite harmful. With 25 parts per million growth was 



' Method as described in Circ. 18, Bureau of Soils, U. S. Dept. of Agriculture. 



