HARMFUL EFFECTS OF ALDEHYDES IjST SOILS. 



25 



EXAMINATION OF THE FIELD PLOTS FOR ALDEHYDE SIX MONTHS 



AFTER APPLICATION. 



That salicylic aldehyde can persist in some soils would seem to be 

 indicated by the fact that the second shipment of Mount Vernon soil, 

 collected six months later than the first, likewise contained salicylic 

 aldehyde; also by the fact that the two samples of Aurora silt loam 

 from Miller County, Mo., collected six months apart, both contained 

 aldehydes. 



In order further to verify this ability of the aldehyde to persist in 

 some soils, the salicylic aldehyde treated field plots were subjected to 

 an examination for aldehyde as had been done with the soil samples 

 from garden and field described in preceding paragraphs. Soil 

 samples were collected from the cowpea plots, the string bean plots, and 

 the garden pea plots, i. e., one sample from each check plot and each 

 salicylic aldehyde plot. 



The six samples were examined for aldehyde. The three check 

 samples contained none; the three treated plots showed the presence 

 of aldehyde. The residues obtained in this procedure for separating 

 aldehydes were tested with wheat seedlings, as described earlier in this 

 paper. The extract from the check plots, which showed no aldehyde, 

 grew plants as well as pure distilled water, whereas the extracted 

 material from the aldehyde treated plots proved harmful to the wheat 

 seedlings. The extract from the cowpea salicylic aldehyde plot de- 

 creased growth 32 per cent, that from the string bean plot decreased 

 growth 27 per cent, and that from the garden pea plot decreased 

 growth 26 per cent. 



The existence of the harmful compound in the soil was also shown 

 in another way by growing wheat in the greenhouse in paraffined wire 

 pots, using the respective soils from the salicylic aldehyde treated 

 plots and the check plots. Two pots, with six plants each, were used 

 for each soil. The plants grew from December 1 1 to January 6. The 

 results of this experiment are given in Table XIV. The table shows 

 that the salicylic aldehyde in the soils of the treated plots six months 

 after the salicylic aldehyde was applied was harmful to wheat. 



Table XIV.— Gro wth of wheat in soil taken from the field plots six months after treat- 

 ment with salicylic aldehyde. 



Plot. 



Cowpea plot 



String bean plot 

 Garden pea plot 



Wheat on 



soil from 



check plots. 



Grams. 

 1.48 

 1.54 

 1.47 



Wheat on 

 soil from 

 salicylic 



aldehyde 

 plots. 



Grams. 

 1.18 

 1.11 

 1.22 



Relative 



growth, 



check =100. 



A similar experiment was made with these soils, except that the 

 crops grown in the pots were identical with those which had grown 



