120 



this soil is not much reduced l)y the addition of large 

 (juanlities of compounds known to be toxic to plants in 

 solution cultures, except when a crop is grown im- 

 mediately after the addition of such compounds. This 

 would indicate that these particular compounds under- 

 go some change in the soil which renders them inert 

 or actually beneficial. 



As has already been noted, the early experiments 

 conducted at this Experiment Station showed that 

 pyridine and quinoline when applied to the soil, were 

 beneficial to both oats and corn. The experiments 

 conducted in 1914-1915 included pyridine, quinoline, 

 nucleic acid, asparagine and naphthylamine, all of 

 which are nitrogenous compounds. These were used in 

 two ratios, the heavier ratio being 1000 parts per million 

 of dry soil, and the lighter being 500 parts per million. 

 The compounds were used without, and in connection 

 with potassium and phosphorus. The results obtainetl 

 with oats and corn are given in Table VII. All of the 

 pots which were not planted to oats were planted to 

 cowpeas instead; the results obtained with the peas 

 are given elsewhere. 



A study of the data obtained with the oat crop shows 

 that the earlier experiments with pyridine and quin- 

 oline are fully substantiated. Nine c. c. of pA'ridine 

 alone increased the oat crop materially; and with pot- 

 ash and phosphorus, the effect of such application is 

 considerably greater than the eft'ect of a complete fer- 

 tilizer, with nitrate of soda as the source of nitrogen. 

 The yields obtained from the quinoline treated pots 

 are similar to those from the pyi'idine treated pots, 

 though not (piite so great. The fact that larger yields 

 are obtained from the larger amounts of these two 

 compounds shows that, when these nitrogenous toxins 

 are nsed in the soil, and not in water cultures, they 

 lose their lo.vic properties entirely, and heeonie highly 

 beiieficidl. Nor can it be arguccl that the addition of 

 ])hosphorus and potassium increases the yield by ex- 

 erting an antitoxic effect on these substances, because 

 a similar increase in yield is obtained by adding these 

 mineral elements to nitrate of soda, asparagine, and 

 nucleic acid; neither of these latter materials is toxic 

 to plants. 



