90 



SPECIAL CORN FERTILIZERS versus A FERTILIZER CON- 

 TAINING A LARGER PROPORTION OF POTASH. 



In bulletin 14 of this station (p. 60) I express the opinion that the 

 special corn fertilizers in the market contain too small a proportion 

 of potash, and an experiment has been made upon the grounds of the 

 station during the past reason to test this point. For this purpose, 

 one-half an acre of land, used some five years previous to 1890 as a 

 pasture without manure, was selected. In 1890, this land was sown 

 with millet for which a moderate application of fertilizer, supplying 

 about twenty-five pounds of nitrogen ; forty pounds of phosphoric 

 acid, and eighty pounds per acre of potash, was made. This half- 

 acre was divided into two equal sections, and to the soil of section 1 

 we applied a fertilizer supplying nitrogen, phosphoric acid and potash 

 in the same quantities in which these ingredients would be supplied 

 by an application at the rate of 800 pounds per acre of a fertilizer 

 having the average composition of seven selected " special corn fer- 

 tilizers" which are among the most common and most widely used. 

 For the soil of section 2, we applied a fertilizer containing a much 

 smaller amount of phosphoric acid, and much more potash. The 

 fertilizers applied as well as the resulting crops and other details are 

 shown in the following table : 



COMPARISON OF FERTILIZERS FOR CORN. 



1 (M-) 



2 (iA.) 



Fertilizer applied, 

 pounds. 



Nitrate soda, 37| Nitrogen, 5.9 

 Dis. b'ne-b'll<,142: Phos. acid 22.7 

 Muriate pTsh, 18 jPotasli, 9 



Supplied in fertil- 

 izer, pounds. 



Nitrate soda. 

 Dis. b'ne-bl'ck,75j 

 Muriate pTsh, 50 



Nitrogen, 3.5 



Plios."acid,12 



Potasli, 25 



Value of 



crop per 



acre. 



$48.05 

 $49.30 



It will be noticed that the combination of fertilizers containing the 

 more potash, and costing almost three dollars per acre less than the 

 others, produced slightly the better crop. The financial advantage 

 in favor of this combination amounts to $4.21, not a large saving, it 

 is true, but ceituinly worth looking after. These two combinations 

 of fertilizers must have left in the soil residues of about the same 

 value. The first supplied the more nitrogen but this will not be 

 retained. It also supplied the greater amount of phosphoric acid; 

 but this is offset by the greater amount of potash supplied by the 

 second combination. 



