4 BULLETIN 164, XT. S. DEPARTMENT OF AGRICULTURE. 



The vanillin was quite harmful in amounts of 400 and 500 parts 

 per million in the Florida sand and was only moderately harmful in 

 amounts of 100 to 300 parts per million. With the Susquehanna 

 sandy loam the vanillin reduced growth considerably when applied 

 at the rate of 300, 400, and 500 parts per million. It was slightly 

 harmful with 100 and 200 parts per mil lion. Vanillin had no harmful 

 effect in the Hagerstown loam — two of the treatments were slightly 

 above the check and three slightly below. The growth in the un- 

 treated soil of the Hagerstown loam was better than in the Susque- 

 hanna sandy loam and considerably better than in the Florida sand. 

 The effect of vanillin in the three soils is shown in Plate II. 



It is seen from this experiment that vanillin is harmful in two of the 

 soils and has no effect in the third. Vanillin is easily oxidized and 

 changed under favorable conditions, and if this took place the action 

 on plant growth would not be noticeable. The Florida sand was found 

 to contain vanillin when sent in from the field and, as would be 

 expected, added quantities of vanillin would not be changed and 

 it would remain as such to have its effect on plants grown in the soil. 

 The Susquehanna sandy loam is also a soil having small oxidizing 

 power and low life activity, and added quantities of vanillin appar- 

 ently remained as such and had their effect on plant growth. The 

 Hagerstown loam is a soil of entirely different characteristics, being 

 highly productive, which indicates good life activities and good 

 oxidizing power. Vanillin when added does not have harmful effects 

 on plants grown in the soil, as it probably does not remain in this soil 

 as such, but is changed or destroyed by the oxidation which is going 

 on in soils of this character. 



In order to study further the action of vanillin in soils and its 

 bearing on soil fertility, the effect of vanillin under field conditions 

 was tested in plots. Three leguminous crops — cowpeas, string beans, 

 and garden peas — were grown to maturity in this experiment, with 

 the following results : 



EFFECT OF VANILLIN ON COWPEAS, STRING BEANS, AND GARDEN PEAS 

 GROWN IN THE FIELD. 



The effect of vanillin in soils under field conditions was tested on 

 plots at the experiment farm of the Agricultural Department at 

 Arlington, Va. Three crops were grown, namely, cowpeas, string 

 beans, and garden peas. These experiments were made during the 

 summer of 1913. The treated plot was adjoined on each side by an 

 untreated plot growing the same crop. Each plot was 8 J feet square, 

 or one-fourth of a square rod; that is, one six hundred and fortieth 

 of an acre. 



