New York Agricultural Experiment Station. 87 



by itself witbout reference to tlie future. Under sneli cir- 

 cumstances a farmer desires to use those forms of fertilizing 

 materials which will be taken up most quickly and completely 

 by the crops. On the other hand, the farmer who owns 

 his land frequently desires to use materials, the plant-food of which 

 will be utilized gradually by crops and which will last through several 

 seasons. It will thus be seen that if one desires a fertilizer which 

 will act at once and be largely used up by the present crop, then he 

 will need to purchase his plant-food in forms different from those 

 pm'chased by the man who desires more lasting benefits, extending 

 through several seasons. 



We will now consider the relative rapidity with which different 

 forms of nitrogen, phosphoric acid, and potash are available for the 

 use of i^lants. 



Nitrogen in the form of nitrate of soda acts most quickly ujDon 

 plants. Under favorable conditions, its influence upon the plant 

 may be seen within twenty-four hours after its application. In the 

 form of suljpliate of ammonia^ nitrogen acts less rapidly than in that 

 of nitrate of soda, but more quickly than in such forms as dried 

 JjJood^ meatrscraj), etc. Nitrogen in the form of hone dust, ground 

 fish, and hone meal become available still less rapidly than in the 

 form of dried blood. In the forms of ^oool ivaste, ground leather, 

 and similiar materials, nitrogen becomes available with extreme 

 slowness. 



Potash in the form of carhonate, as in ashes, acts more rapidly 

 than in the form of sulphate or muriate. Muriate acts with a little 

 greater rapidity than sulphate, but the difference in availability 

 between the different forms of potash is not nearly as strongly 

 marked as in the case of the different forms of nitrogen. 



Phosphoric Acid, in the form of solidjle phosphate of lime (acid 

 phosphate, superphosphate) acts most rapidly. It acts less rapidly 

 in the form of reverted or precipitated pthosphiate of lime, and least 

 rapidly in the insoluble form, such as ground rock. According to 

 the weight of evidence, soluble phosphoric acid, whether made 

 from bones, bone-black, or rock, has the same effect and value as 

 plant-food, so far as the soluble phos))horic acid is concerned. 



The following tables will serve to give a general idea regarding 

 the length of time fertilizing constituents in some different forms 

 will remain in the soil, or, in other words, regarding the relative 

 availability of the different forms of fertilizing constituents : 



