i908.] PUBLIC DOCUMENT — No. 33. 43 



IV. — North Corn Acre. — Special Fertilizer v. Ferti- 

 lizer Richer in Potash. 

 This experiment, which was begun in 1891, is designed to 

 test the question whether the special corn fertilizers as offered 

 in our markets are of such composition as seems to be best 

 suited for the production of corn and mixed hay in rotation. 

 The experiment occupies an acre of ground, and is divided 

 into four equal plots, numbered from 1 to 4. Plots 3 and 4 

 were sown to millet during the first two years of the experi- 

 ment, but with this exception their treatment has been the 

 same as that of plots 1 and 2, 3 being a duplicate of 1 both 

 as regards fertilizer application and crops produced, and 4 a 

 duplicate of 2. The field has been in mixed grass and clover 

 during three two-year periods, 1897-98, 1901-02 and 1905-06. 

 With these exceptions, and with the further exception referring 

 to millet noted above, corn has been the crop. Whenever the 

 field has been put into grass and clover, it has been seeded in 

 the standing corn of the previous year. Plots 1 and 3 have 

 yearly received an application of fertilizers (a home mixture), 

 furnishing nitrogen, phosphoric acid and potash at the rate per 

 acre which would be supplied by 1,800 pounds of fertilizer 

 having the composition of the average of the special corn ferti- 

 lizers analyzed at this station. We have made but one change 

 since 1899, as this average changes but little from year to year. 

 The average composition of such fertilizers at that time was as 

 follows : — 



Per Cent. 

 Nitrogen, ......... 2.37 



Phosphoric acid, . . . . . . . .10.00 



Potash, 4.30 



The fertilizer used on plots 2 and 4 has been a home mixture 

 richer in potash and much poorer in phosphoric acid than the 

 mixture representing the average corn fertilizers offered in the 

 market. The difference in the application of the fertilizer ele- 

 ments is made clear in the following table : — 



