FIELD TEST WITH A TOXIC SOIL CONSTITUENT: VANILLIN. 7 



while the vanillin plot produced 717 pounds per acre of vines and 120 

 pecks of peas. This is a reduction of 30 per cent in vines and 20 per 

 cent in marketable peas, due to the presence of vanillin. 



Plate IV, figure 2, shows the harvested crop grown in the untreated 

 plot and in the vanillin plot. 



EFFECT OF VANILLIN ON STRING BEANS. 



String beans were also affected by vanillin. The beans were sown 

 May 21, 1913; they germinated well and came up uniformly. The 

 plants in the untreated plot grew better and were more thrifty than 

 those in the vanillin plot. Plate III, figure 3, shows the comparative 

 growth in the early stage, and from this it is seen that the untreated 

 plants are much larger. The crop was harvested July 22. The 

 beans were picked from the vines and measured. The results are 

 given in Table IV. 



Table IV. — ■ Yield of string beans as affected by vanillin in the field. 



Treatment. 



Yield per plot. 



Yield per acre. 



Vines. 



Beans. 



Vines. 



Beans. 





Pounds. 

 3.55 

 2.94 



Pounds. 

 1.90 

 1.66 



Pints. 

 4.75 

 4.15 



Pounds. 

 2,272 

 1,882 



Pounds. 

 1,236 

 1,062 



Pecks. 

 190 



Check 6 



166 







Average check 



3.24 

 2.71 



1.78 

 .55 



4.45 

 1.50 



2,070 

 1,734 



1,149 

 352 



178 



56 









.53 



1.23 



2.95 



336 



797 



122 







The average yield for the check plots was 2,070 pounds of vines per 

 acre and 178 pecks of beans per acre. The yield of the vanillin plot 

 was 1,734 pounds of vines per acre and 56 pecks of beans per acre. 

 This is a decrease of 336 pounds of vines per acre and 122 pecks of 

 beans per acre. The harvested crop from the untreated plot and the 

 vanillin plot is shown in Plate IV, figure 3. 



PRESENCE OF VANILLIN AND ITS EFFECT IN THE SOIL SIX MONTHS 



AFTER APPLICATION. 



The question of the length of time the vanillin would persist in the 

 Arlington soil and have an influence on its crop-producing power has 

 also been investigated by a chemical study in the laboratory and by 

 pot tests. Samples of soil for these purposes were obtained from the 

 plots the last of November, six months after the substance was 

 applied, and after a crop had been matured. The soils were exam- 

 ined for vanillin by the method already described by Shorey. 1 The 

 method, in brief, consists of making an alkaline extract of the soil. 

 The extract is acidified and filtered and then shaken out with ether. 



J J. Agr. Research, 1, 357 (1914). 



