118 MASSACHUSETTS HORTICULTURAL SOCIETY. 



bridge in the college report as his only authorized agent, as 

 follows : 



" Stockbridge Fertilizers. These fertilizers are made for differ- 

 ent crops by formulas worked out by Prof. Stockbridge, of the 

 Massachusetts Agricultural College, and have given extraordinary 

 results, at small cost, producing, for example, from seventy-five to 

 one hundred bushels of corn to the acre, corresponding results 

 with other crops, without any manure^ at a cost of about twenty- 

 five dollars per acre, and without exhausting the soil, but leaving 

 it richer by actual test. That the farmer may get the right in- 

 gredients, separately, or properly compounded, we are entrusted 

 by Prof. Stockbridge as the only parties in the country to furnish 

 them under his name. Pamphlets, containing the formulas, and 

 other valuable information, sent free." 



The general theory of Prof. Stockbridge has been, in most points, 

 familiar learning for a generation past, at least. It is that growing 

 plants are made up of certain elements which they obtain from the 

 soil, from the air, or from water ; that by chemical analysis it is 

 ascertained what those constituent elements are, and in what pro- 

 portion they exist in a given plant or crop ; that the elements fur- 

 nished by the soil ai*e nitrogen, potash, phosphoric acid, with lime, 

 soda, magnesia, silica, etc. 



Prof. Stockbridge assumes that all the elements of plant food 

 are supplied in abundance by the air and water, and the natural 

 condition of ordinary soil, except three, nitrogen, potash, and phos- 

 phoric acid, and for the purposes of this discussion this assumption 

 is not questioned. Then, he says, apply to the soil these three 

 substances in the proportion in which they exist in the crop, and 

 this is the true manure to produce such a crop. And this is not 

 controverted, and is in theory correct. 



Referring to his published formulas, we find them all to be in 

 this form : "To produce fifty bushels of the grain and its natural 

 proportion of stover to the acre more than the natural yield of the 

 soil, use " so many pounds of nitrogen, so many pounds of potash, 

 and so many pounds of phosphoric acid. To produce fifty bushels 

 more than this natural yield, he applies just as much nitrogen, 

 potash, and phosphoric acid as are found in fifty bushels of corn 

 and its stover. 



Prof. Stockbridge says in the college report, " Allusion has 

 already been made to the curious form of the statement of the for- 



