122 MASSACHUSETTS HORTICULTURAL SOCIETY. 



more than the land would produce without it, for that was the re- 

 sult. The next year he gained thirty bushels. The results are 

 these : Pie applies the elements of seventy bushels, and removes 

 one hundred and four, phis sixty-four, a total of one hundred and 

 sixty-eight bushels, or ninety-eight bushels more than he com- 

 pensated, and still the land improves in condition. If such a dis- 

 covery has reall}^ been made, the claim which the president of the 

 college makes in connection with it is very moderate " that the 

 money expended upon the college will yield a larger rate of interest 

 than any other investment which the State has ever made." * 



All the formulas are given in what the professor calls this " curi- 

 ous form : " " to produce so much more than the natural j'ield of 

 the land." If vve could assume that each acre has a permanent 

 natural yield, which it can forever maintain without manure, then 

 we might apply fertilizers enough for the crop in excess of that 

 natural yield, and not exhaust the soil. If 3'our field will yield 

 fifty bushels, without manure, you may forever supply fifty and 

 remove a hundred, and not exhaust the soil, though it would still 

 be difficult to see how it could improve. It is enough to say that 

 we have no such soil, and nobody will contend that we have. In 

 all the experiments given, the " natural yield," as it is termed, is 

 found by observing what a portion of the field not manured that 

 year produced. Pi'of, Stockbridge in the statement last quoted, 

 says, the " capacity of the land at that time, etc., was thirty-four 

 bushels." 



The following extract from the circular issued by Prof. Stock- 

 bridge's only authorized- agent shows that the common notion that 

 we must put on to the land as much as we take off is not contro- 

 verted : 



" If fifty bushels of corn remove from the soil sixty-four pounds 

 of nitrogen, seventy-seven pounds of actual potash, and thirty-one 

 pounds of soluble phosphoric acid, we cannot raise many such crops 

 without exhausting the soil, unless we are sure we put back in 

 the form of manure, or fertilizers, as much as we take off in 

 the crops."! 



This, it will be observed, is utterly inconsistent with the formu- 



* Thirteenth Aunual Report of the Massachusetts Agricultural College, 

 page 15. 



t The Stockbridge Fertilizers and Formulas, p. 5. 



