113 



>vhicli had iiol rc'cei\c'(l phosphaU- in llie- UcaliiKUls 

 given the oals, and all were then phinted to corn. 



The corn crop grew until the hirgest phints w^erc In- 

 ginning to show tassels, when the corn was cut, air dried 

 in the greenhouse, and weighed. 



CoNcr.usiONS From Tin: Fmlst Year's Work. 



The following conclusions seem to be justified, based 

 on the experiments conducted during the fall, winter 

 and si)ring of 1913-1914: 



1. Thai the |)oor soils experimented upon were not 

 benetited by tiie application of such substances as car- 

 bon black, pyrogallol, or calcium carbonate. 



2. That coumarin and vanillin, when added to soil. 

 were toxic to plants only when used in large amounls. 

 and when these large amounts were added to the soil 

 at time of seeding. 



3. That nitrogenous compounds like pyridine and 

 ([uinoline were beneficial, rather than harmful, as has 

 been found to be true by means of water cultures. 



4. That four or five months after the addition of 

 coumarin and vanillin to a soil, no toxic effect on corn 

 \\as a])parent. 



T). 4'hat i)laiits must be grown lor longer periods 

 than two or three weeks, in fertility work, if true con- 

 clusions are to be reached. 



6. That these conclusions were ])orne out in all of 

 the four widely different types of soil used in this work. 



Exfi:rimi:nts Conducteo in 1914-1915. 



One of the experiments conducted during the second 

 year was designed to show whether or not repeated 

 applications of toxic compounds to soils would finally 

 result in marked injury to plant growth. To study this 

 point a number of pots used in the work of the first 

 year were carried into the work of the second year 

 with the same treatments, and the same croj)s as wire 

 used in the beginning of the work. The data so obtain- 

 ed are given in Table V. All of the data concerning 

 these pots during the first year, may be found by refer- 

 ence to 'fable I. 



During the summer of 191 f, the i)()ts were left dry and 

 undisturbed in the greenhouse. In the fall of this year, 

 these pots were treated as shown in the first column of 



