PERCENTAGE YIELD OF EACH CROP FN' EACH STATE, ETC. 461 



and original differences in the character of the soil, to climatic condi- 

 tions favorable or unfavorable to agricultural production, and in part 

 also to better agricultural methtxls obtaining in some secti«»ns, it is true 

 that over large and most productive areas of our country, the fertility 

 of the soil has sufiered appreciable diminution. 



If we contrast the Xew England and Middle States, f«»r example, 

 with those < f the Central or the Xorth-western and Western States, we 

 shall fi: d, alt'iough the former were but a few years ago surpassed in • 

 pr.Kluciivenes- by the latter, that, during the short perio<l of fifteen or 

 twenty years, the yield of the latter has fallen off, while that of the 

 Xew England and 3Iiddle States has increased, so that at present the 

 acreage yield of these Xew England and Middle States surpasses that 

 Xorth-western and Western States and of the Central States. 



This is the more remarkable, in view of the fact that these same 

 lands which have so increased in productiveness have been under the 

 plow for at least a century longer than those of the West. 



This result is probably due largely to inherent differences in the soils 

 of the several sections. The rocks of Xew England, which by their 

 gradual disintegration have farmed these lands, will probably l)e found 

 richer in the mineral constituents of plant food than the rocks of the 

 West. But it is beyond question that the early settlers upon these 

 western lands fi>uud them rich in the elements of plant food, which 

 through ages had accumulated. 



The continued cropping and wasteful methods which characterized the 

 early years of western agriculture appear, however, to have partly, at 

 least, exhausted these accumulated stores of food, as evidence*;! by di- 

 minisheil crops. 



As is well known, the cereals require for their development large 

 quantities, comparatively, of jwtash and phosphoric acid, and these 

 two mineral constituents exist in comparatively very small quantities 

 in the rocks or in the soil derived from them. It follows, therefore, 

 that they would naturally be soonest removed from the soil by contin- 

 ual cropping, and, as is known, this removal has necessitated the re- 

 storation to the soil of these constituents through the application of 

 products containing them. 



The so-called commercial fertilizers which have within the past few 

 years been manufitctured and sold in the country, especially in the 

 Xew England and Atlantic States, are chiefly valuable for these two 

 constituents. 



If we take as a basis for our calculation the returns for 1879, we may 

 readily determine the amount of these important mineral constituent* 

 which is annually taken from our soil by these crops. 



