150 BOARD OF AGRICULTURE. [Pub. Doc. 



used, 80 that the only way to make it effective is to limit the 

 potash, supplied in the manure, to such an extent that the 

 plant does not find in the soil in assimilahle form sufficient 

 for its immediate needs. It is possible that this practice 

 ma}' be permissible upon certain soils and with certain kinds 

 of plants, but not with others, the indications thus far 

 obtained at Rhode Island pointing strongly in that direction. 

 Until it is learned more definitely with what plants and upon 

 what soils soda may be considered as capable of replacing 

 potash in our manure, one is not safe in allowing the soda 

 question to influence him materially in the choice between 

 nitrate of soda and other sources of nitrogen. So much can 

 be stated, however, viz., upon soils which are acid, nitrate 

 of soda has for several years invariably given better results 

 with beets, spinach, lettuce, asparagus and several other 

 plants than the same quantity of nitrogen as sulfate of 

 ammonia, oven when lime was applied in each case at the 

 same rate.* 



Organic Nitrogen. — Under the general term organic 

 nitrogen is classed the nitrogen of animal and vesretable sub- 

 stances. Among those most frequently met with in our 

 markets may be mentioned dried blood, finely ground fish, 

 tankage, bone, horn meal, hoof meal, cotton-seed meal, lin- 

 seed meal and castor pomace. The agricultural value of the 

 nitrogen in these different materials varies widely, dependent 

 upon the chemical and physical character of the soil, the 

 temperature, moisture and other factors which determine 

 how rapidly decomposition is brought about, ammonia pro- 

 duced, and this in turn transformed into nitric acid. 



P. Wagner and Dorsch f give the following as the rela- 

 tive degrees of assimi lability of the nitrogen of a number 

 of diflerent organic substances, determined in a three-years 

 successive trial, in pots, and with the same soil, whereby 

 the cumulative as well as the immediate eflect could be 

 observed. The assimilability of nitrate nitrogen is placed 

 at 100 for purposes of comparison. 



* Compare the results secured in experiments upon the effect of lime upon the 

 growth of plants. Reports Rhode Island Agricultural Experiment Station, 1893- 

 1899 inclusive. 



t Die Stickstoflfdiingung, Berlin, p. 247. 



