EXPERIMENTS WITH POTATOES. 



155 



In the Year Book of the United States Department of Agri- 

 culture for 1896, are given figures which agree very closely with 

 the above. These are compiled results and from the close 

 agreement it would seem to indicate that the composition of 

 potatoes, so far as nitrogen, phosphoric acid and potash are con- 

 cerned, is fairly uniform. 



Assuming these figures to fairly represent potatoes as grown 

 in Maine, a crop of 200 bushels, weighing six tons, would 

 remove thirty-seven pounds of nitrogen, sixteen pounds of phos- 

 phoric acid and fifty-eight pounds of potash. 



If the amounts and proportions of fertilizing elements re- 

 moved by a crop could be taken as a guide in preparing a field 

 for that crop, the problem of supplying the proper amount and 

 kind of plant food to the soil would be much simplified. To 

 manure a field for a crop of potatoes, nitrogen, phosphoric acid 

 and potash would have to be added in about the proportions 

 given above and in sufficient quantity to supply the vines and 

 tubers the land was expected to yield. A formula made up on 

 this basis would be very materially different from any mixed 

 fertilizer on the market and would contain the fertilizing ele- 

 ments in about the following proportions : Nitrogen, 5 parts ; 

 phosphoric acid, 2 parts ; and potash, 8 parts. Twenty-six dif- 

 ferent brands of so-called potato fertilizers were sold in the 

 State in 1899. The table which follows show how these goods 

 were made up : 



COMPOSITION^ OF SO-UALLED POTATO FERTILIZERS 



IN 1899. 



SOLD IX 



MAINE 





3 



be 







32 



1 





% 

 L.'i— 2.5 



2-2.5 



2.5-3.5 



% 



8-9 



6-9 



5.5-8 



•^ :^25 





4 6 



S bra n il 8 



7—10 







The first twelve brands mentioned cannot properly be called 

 potato or special fertilizers as their composition is practically the 

 same as all general purpose goods. The formulas of the last 

 eight, approximate more nearly to the popular idea of what a 



