VANILLIN AS A SOIL CONSTITUENT 325 



place the action on plant growth would not be noticeable. In 

 as much as the Florida sand was found to contain vanillin when 

 sent in from the field it was to be expected that vanillin would 

 persist in this soil, that added vanillin would not be changed and 

 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 apparently remained as such and had their effect on 

 plant growth. The Hagerstown loam is a soil of entirely differ- 

 ent 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 condi- 

 tions 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, Virginia. Three crops were grown, namely, cow- 

 peas, 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| feet square, or one-fourth of a square rod. The soil 

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

 in organic matter. The ground is level and has surface drain- 

 age. The soil throughout these plots and their controls is uni- 

 form, so the results secured should not be considered as unduly 

 influenced by irregularities due to non-uniformity of the soil in 

 different plots. The soil is of an acid nature. The land was 

 plowed early in May and prepared for seeding. 



