108 



are very loxic lo |)laiils in water cultures, have not 

 Taeen more hiifhly injurious to com and oats grown in 

 soil. Tl is true tlial Hic oat crop following immediately 

 alter tlie appliealion ol" these compounds has been 

 somewhal injured; but it is also true that the corn crop 

 "following several months after the treatments, has not 

 only not been injured, but has, apparently, been slight- 

 ly impi-oved. The combined weight of the two crops 

 Ironi llie several pots treated with vanillin and cou- 

 anarin is in most cases greater than the combined 

 weight of tlie crops fYom the untreated pots. 



The results from the use of pja-idine and quinolin^, 

 both of which are nitrogenous compounds, were entire- 

 ly unexpected. In water cultures, these substances are 

 -almost always toxic to plants: but in soil cultures, both 

 of the compounds have considerably increased the crop 

 yields. The cond)ined crops obtained from pyridine 

 and the ({uinolinc treated pots are very much larger 

 than those obtained from the checks; indeed, nitrate 

 of soda has been but little more effective than have 

 ihe.se two organic "toxins." 



Rksi i;rs of Pot Experiments With Cecil Clay Soil. 



Table II sliows the results obtained from Cecil clay 

 soil. This test was conducted in 2-gallon pots, each pot 

 eontainmg 20 pounds of the screened soil. The first 

 crop groAvn was oats, which crop was planted in the 

 fall of Un'X When the oats were fully headed out the 

 following spring, the crop was harvested, allowed to 

 hecome tlioroughly air dry, and weighed. All pots 

 which liad not received acid phosphate in the treat- 

 ments given the oat crop, were given 9 grams of acid 

 phosphate and i)lanted to corn, in the spring of 1914. 

 The corn was harvested when the largest plants were 

 beginning to show tassels, and weighed, after it had 

 become tlioroughly air dry. The table of results fol- 

 lows : 



