308 AGRICULTURAL ANALYSIS 



upon the vitality of seeds was first studied. The result of these 

 experiments was to show that the cyanamid compound, except 

 in very minute quantities, injuriously affected the vitality of the 

 seed. As the amount is increased the toxic effect becomes more 

 and more noticeable, not only in the retardation of germination, 

 but also upon the health and vigor of the ypung plant. Wheat is 

 better able to resist this action than peas. Nevertheless the wheat 

 plants in the tests which contained the larger amount of cyanamid 

 frequently turned black, withered and died after reaching a 

 height of from three to five inches. It is believed that cyanamid 

 compound in amounts not greater than five milligrams of nitro- 

 gen to 100 grams of soil, does not prove injurious to the germinar 

 tion of seed. Toxic effects were markedly noticeable, on the 

 other hand, with amounts of cyanamid containing between 10 

 and 12 milligrams of nitrogen per 100 grams of soil. The potas- 

 sium compound appears to be more injurious in action upon the 

 life of the seed and young plants than the calcium salt. In regard 

 to the value of cyanamid compound as a fertilizing material, the 

 experiments were confined to the study of its degree of nitrifica- 

 tion. It would seem from a consideration of the data secured that 

 as the comparative amount of the cyanamid compound is increased 

 in the soil there is a corresponding decrease in the rate of nitrifi- 

 cation. This is probably due, as already indicated, to the toxic ac- 

 tion upon the nitrifying organisms. It may be due partly also to 

 denitrifying changes leading to a reduction of a part of the 

 nitrogen to the free state. The conversion of the nitrogen of the 

 cyanamid into available forms is probably continuous under 

 favorable conditions, though not uniformly so. The first stage of 

 the process may be considered possibly as purely chemical, since 

 water at ordinary temperatures converts the nitrogen of cyan- 

 amid into ammonia. Further changes are brought about 

 through the agency of living organisms, and are necessarily slow- 

 er, depending for their activity on many factors, prominent among 

 which is the relative proportion of the cyanamid compound 

 present in the soil. 75 



270. Later Experiments with Cyanamid. Grandeau has sum- 

 75 Chemical News, 1906, 94 : 150. 



