Nitrogenous Fertilizers 59 



ture reaches 37 F., and when in addition sufficient mois- 

 ture is present. Hence, a material which might give 

 excellent results when applied to a crop that grows through 

 a long period in a climate where the season is very warm 

 and moist, might be very unsatisfactory where the season 

 is short, cold and dry. These are a few of the conditions 

 which modify the rate of the decay of the same material. 

 The object of the application should also be taken 

 into consideration. The rate of the feeding of the plant 

 with nitrogen in organic forms is measured by the rate 

 of decay of the organic material containing it, while when 

 nitrate is used, its feeding is direct. The result is really 

 a sort of feeding of the soil in the one case, and a direct 

 feeding of the plants in the other. Where the purpose 

 is to get the largest proportionate increase in crop from 

 the least amount applied, either the nitrate, or the am- 

 monia, or the more active of the organic forms, would be 

 likely to give the best returns. Whereas, if the object 

 to be attained is not so much a large increased crop as it 

 is increase in the future productive capacity of the soil 

 in respect to this element, the slower acting materials 

 will often answer the purpose quite as well as the use of 

 the more active nitrate form, because in this form no 

 insoluble combinations are formed, the nitrate is freely 

 movable, and if the plants do not absorb it, and heavy 

 rains come, the water containing the nitrate is carried 

 through the soil into the drains and the nitrogen lost. 

 The disadvantage of the nitrate is, then, that there is 

 a greater possibility of loss from its use than from the 

 use of materials which are either insoluble, or which are 

 readily absorbed. Ammonia, while perfectly soluble, is 

 fixed by the other substances in the soil, and is not, there- 

 fore, readily leached out. If, however, heavy applications 



