322 J. J. SKINNER 



given, together with the action of vanillin on clover in soil in 

 pots and with wheat plants grown in several soils of different 

 characters. 



EFFECT OF VANILLIN ON SOILS IN POTS 



An experiment to determine the effect of vanillin on clover was 

 made by growing clover in Chester loam soil in large pots. Or- 

 dinary clay flower pots holding 6 pounds of soil were used. One 

 pot was untreated; the other had a total of 300 parts per million 

 of the vanillin added to it. 



When the soil was potted, 100 parts per million of the vanillin 

 were added and clover then sown, 0.5 gram of seed per pot. The 

 clover was sown April 12, and came up well. On April 28, 50 

 parts per million of vanillin were added in solution through a 

 funnel passing into the soil nearly to the bottom of the pot, thus 

 avoiding direct contact with the tops or roots of the clover. In 

 May 15, on June 1 and again on June 10, 50 parts per million 

 were added, making the total application 300 parts per million. 

 The experiment was discontinued June 21, 1912. 



The effect of vanillin was noticeable from the first. The 

 harmful effect is shown by comparing the untreated pot and the 

 vanillin-treated pot shown in figure 1 . The vanillin-treated plants 

 were normal in appearance but stunted in growth. The green 

 weight taken at the termination of the experiment was 8 grams 

 from the untreated pot and only 3.8 grams from the vanillin- 

 treated pot, a decrease of 53%. 



The soil used in this experiment was a soil of moderate pro- 

 ductiveness, and vanillin applied to it at different periods of the 

 growth of the plants was distinctly harmful. Other experiments 

 were made to test the effect of different amounts of vanillin in 

 several soils, each having different properties and being of differ- 

 ent geological origin. In the following experiments wheat was 

 used as the test crop and the total application of vanillin was 

 made before the soil was potted and seeds planted. 



In this experiment the effect of vanillin in several soils was 

 studied by growing wheat in pots. The soils used were infertile 

 Florida sand, an infertile sample of Susquehanna sandy loam, 



