August 12, 1887.] 



SCIENCE. 



n 



once connected northern America with western Europe. Later, 

 others came from Asia. At that time the physical geography of 

 the northern hemisphere was widely different from the present. 



These various data have as yet been but imperfectly studied : 

 when they shall have received the attention they merit, we may 

 confidently calculate on a large increase in our knowledge of the 

 course of events in ancient America. 



ECONOMY IN MANAGEMENT OF SOIL.> 



In this great metropolis, or wherever our association meets, we 

 are shown with pride the abounding evidences of the progress of 

 a great nation, and the material prosperity of its people. 



Tracing this visible wealth to its source, we find that it has all, 

 with insignificant e.Kceptions, been produced from the soil. The 

 American inheritance was a fertile soil. A policy perhaps war- 

 ranted by the circumstances, but none the less improvident, has 

 marked the growth of the nation. Generation after generation has 

 recklessly drawn upon the stored fertility of the land, with no 

 systematic effort at restitution, not only to supply the current sup- 

 port of people, but the surplus which has provided all our apparent 

 wealth and private improvements. 



The rapidly increasing demands of our own country are met, and 

 more than met, so far as mere quantity is concerned, for a great 

 surplus is annually sent abroad. For twenty years agricultural prod- 

 ucts have constituted three-fourths of the total exports from the 

 United States, while in single recent years this proportion has 

 reached eighty-three per cent, and amounted in value to nearly 

 nine hundred million dollars. And it is manifest that this super- 

 abundance of soil-products will continue, despite any possible in- 

 crease in population, at least well into the ne.xt century. We boast 

 of our great exportation of soil-products, forgetting that this really 

 means the sending to foreign lands great blocks of our store of 

 natural fertility, thus disposing of the main source of our material 

 wealth by the ton and by the million. The steady reduction in the 

 fertility of the soil, which results from the annual draught by crop- 

 ping and the absolute loss incident to ordinary disposition of the 

 crops, is much greater than commonly understood, and a matter so 

 important as to demand serious consideration. 



For present purposes it is sufficient to refer to only three elements 

 of plant-food, which are of vital importance, and in which the soil 

 is most likely to be, or to become, deficient. A computation based 

 upon the mean annual agricultural products of the United States at 

 the present time, the average composition of these products as far 

 as known to chemistry, and the cash value of the chief fertilizing- 

 materials in domestic markets, gives the following stated quantities 

 and values of the three elements named, which are taken from the 

 land by the farming operations of every year : — 



4,000,000 tons of nitrogen, worth $360 per ton $1,440,000,000 



3,000,000 ,, potash, 100 , 300,000,000 



2,000,000 ,1 phosphoric acid, 120 „ 240,000,000 



Total value $1,980,000,000 



The effect upon the soil depends, of course, upon the disposition 

 of the products embodying these enormous quantities and values. 

 Fortunately, a very large part remain upon or are returned to the 

 land, in the process of harvesting and preparing for market, and 

 more in the form of water and residues incident to consumption. 



On the other hand, there are vast absolute losses resulting from 

 the well-known wastes of towns and cities, besides the portions 

 actually sent to foreign countries. To exactly apportion the dispo- 

 sition made of these products, and hence of the fertiHzing elements 

 represented thereby, is impossible ; but as to the latter, a rough 

 approximation divides the total into three parts, respectively remain- 

 ing on the land, returned to the soil, and wholly removed from it. 



This country imports the agricultural products of other countries 

 in considerable quantity, but in kind far less important to the 

 question in hand than our exports. 



The articles exported are largely of a character especially rich in 

 plant-food. Making due allowances, therefore, I estimate the 



^ Abstract of an address before the Section of Economic Science and Statistics 

 of the American Association for the Advancement of Science, at New York, Aug. 

 10-17, 1887, by Henry E. Alvord, C.E., of Amherst, Mass., vice-president of the 

 section. 



average exportations as representing thirteen per cent of the 

 fertility value of our total products, and our absolute wastes at 

 home at more than twenty per cent additional. Together 

 these constitute a full third of the figures above given, or 

 an annual removal from American soil, of nitrogen, potash, and 

 phosphoric acid, worth, in the markets of this city to-day, more 

 than six hundred million dollars. By our present system, or rather 

 continued improvidence in the production of the necessaries of life, 

 we are thus diminishing, at this alarming rate, the original capital 

 of our foundation industry. 



When products are exported, mainly food, which are worth seven 

 hundred million dollars on our shores, there is included plant-food, 

 all needed at home, which we cannot replace for one-third of that 

 sum. 



This fertility never comes back. It goes to enrich other lands, 

 or is washed into seas from which we do not ever get the fish and 

 the carp. Those of us who are contending with impoverished soils 

 are well placed to appreciate the sober subject of agricultural ex- 

 haustion, and are in duty bound to send an earnest word of warn- 

 ing to those who labor on newer lands. The researches of modern 

 times have done much in establishing truths of practical value re- 

 garding the effect upon the fertility of the land, of the removal of 

 different crops and products, and hence teaching us what should 

 be consumed at home, and what may be profitably sold. 



Thus, if ton after ton of farm-produce be removed from a 

 Western farm to an Eastern market, or from any American farm to 

 a European market, it makes a great difference eventually, to the 

 land where produced, and to its owner or user, whether these tons 

 be cotton or corn, beef or butter. 



The following table illustrates this point : — 



Cottonseed-meal. . . 



All 'oil-cake' and) 

 'oil-meals' / 



Tobacco 



Beeves alive 



Dressed beef 



Pork products 



Wheat 



Wheat-flour 



Corn (maize) 



Cotton 



Butter 



Mean Annual 

 Exports in 



Approximate 



Value of I Ton 



at Place of 



Export. 



S 26, 



(34 bus.) 34. 

 (lobbls.) 50, 

 (36 bus.) 23. 

 (4 bales) 200 

 (40 tubs) 400 



Value of the 

 Plant-Food 

 in I Ton. 



Percentage of 



Plant-Food 



Value on the 



Market-Value 



I Ton. 



$28.04 

 23.80 



13.99 

 13.43 



8.75 

 6.25 



It merely mitigates the evil presented, to note that the soil holds 

 large quantities of plant-food still in store ; that nature has pro- 

 vided supplies of mineral manures in concentrated form, deposited 

 in various places ; and that some investigators yet believe they will 

 prove conclusively the assimilation by plants of the free nitrogen of 

 the atmosphere. 



Should this much-disputed question of nitrogen-supply be so 

 settled, it would certainly remove a vast deal of anxiety, trouble, and 

 expense ; for, as we have seen, nitrogen constitutes three-fourths in 

 value of the plant-food annually used by crops. But the prevalence 

 of the belief that the growing plant depends almost exclusively upon 

 the nitrates of the soil, and has no power to assimilate the free 

 nitrogen of the air, is amply shown by the market-prices of am- 

 moniated manures and the extent of their sale and use. 



The trade in commercial fertilizers has reached wonderful pro- 

 portions, and agriculturists hail with joy the discovery of every new 

 deposit like the potash-salts of Germany and the mineral phosphates 

 of Canada and the Carolinas. But the expense incident to mining, 

 manipulation, and transportation, greatly impedes the use of these 

 natural stores, and makes the more important every means of hus- 

 banding the home resources of every acre of valuable land. If the 



