New York Agricultural Experiment Station. 



225 



Considering the four rears' crops as a wliole the largest money 

 profit came from the use of one thousand pounds of fertilizer. 



For crop needs.— This, matter may be looked at from another 

 side, viz.: The relation of the nitrogen, phosphoric acid and 

 potash in the fertilizer to the amounts of their ingredients taken 

 up by the tubers and tops. 



There are two points of view from which to discuss the use of 

 fertilizers — the needs of the crop, and the capacity of the soil 

 to supply plant food. In this instance the capacity of the soil 

 at its weakest point is measured by the yield of potatoes where 

 no fertilizer was applied. * 



In making the comparisons which follow, the weight of tops 

 is assumed to be two-thirds that of the tubers and the composi- 

 tion of the tubers and tops is taken from the averages of Ger- 

 man analyses which are somewhat higher for tubers than 

 American analyses. 



Table X gives a comparison between the largest quantities of 

 nitrogen, phosphoric acid and potash which the average crop 

 was likely to have taken up, and the amounts of these ingre- 

 dients in the fertilizer applied. 



Table X. — Fertilizer Elements in Crops and in Fertilizers. 



15 



