FIELD TEST WITH A TOXIC SOIL CONSTITUENT : VANILLIN. 5 



The soil on which these experiments were made is a silty clay loam, 

 low in organic matter. The ground is level and has surface drainage. 

 The soil throughout these plots and their controls is uniform, so the 

 results secured should not be considered as unduly influenced by 

 irregularities due to nonuniformity of the soil in different plots. 

 The soil is of an acid nature. The land was plowed early in May and 

 prepared for seeding. 



Four applications of vanillin were made. The first on May 20, 

 one day before the planting of seed. The other three applications 

 were made periodically during the growth of the crops — May 28, 

 June 5, and June 24. The vanillin was applied by dissolving in water, 

 sprinkling the solution uniformly on the surface of the ground before 

 planting, and raking the soil thoroughly. The remaining applica- 

 tions were made after planting by sprinkling the solution between 

 the rows of plants, the soil being subsequently cultivated. The total 

 application was at the rate of 285 pounds per acre, in four equal parts. 



The crops germinated uniformly. The effect of the vanillin was 

 noticeable from the beginning and throughout the experiment. 

 The growth was stunted, though the plants grew slowly to maturity, 

 and were harvested. 



EFFECT OF VANILLIN ON COWPEAS. 



The cowpeas were sown May 21, 1913, the plots having been 

 previously prepared, and were harvested September 7, 1913. The 

 plants in the untreated plots made more vigorous growth and had 

 a better color than those in the vanillin-treated plot. The vanillin- 

 treated plants had a pale-green color and grew slenderer than those 

 on the untreated plot. The appearance of the plants on June 27 

 is shown in Plate III, figure 1. The four rows of plants growing on 

 the left are on the vanillin-treated plot, and the four rows on the 

 right on the untreated plot. The picture shows that at this stage of 

 growth the vanillin has greatly affected the cowpeas. This effect 

 was even more marked as the crop approached maturity. When 

 mature the peas were picked from the vines and weighed. The 

 weight of the cowpea vines was taken, and after drying the weight 

 of the cured hay was also determined. In Plate IV, figure 1, are 

 shown the vines and pods as taken from the untreated and treated 

 plots. The effect of the vanillin in depressing yield is here also 

 apparent. 



In Table II are given the yields obtained in this experiment with 

 vanillin and cowpeas. The weight of vines and pods is given as 

 obtained from the individual plots and also in terms per acre. 



