864 



SCIENCE 



[N. S. Vol. XX\^I^. No. 729 



the products of the soil, as iu grain aud 

 bone and animal fertilizei"s. Of course, if 

 we raise crops only half as large as are 

 possible under our normal conditions of 

 rainfall and sunshine, then our draft upon 

 the soil is so much less ; and if we i-etiirn in 

 farm fertilizei-s a part of the fertility re- 

 moved in crops, we may still farther post- 

 pone the day when the soil will refuse to 

 honor the drafts we try to make. 



It would seem not only important and 

 appropriate, but especially necessary, to 

 emphasize these facts, if from the position 

 of highest agriciiltural authority should 

 continue the wide-spread promulgation of 

 the remarkable theory: 



That practically all soils contain sufficient 

 plant food for good crop yields, that this supply 

 will be indefinitely maintained ;° that there is 

 another way in which the fertility of the soil can 

 be maintained, viz., by arranging a system of rota- 

 tion and growing each year a crop that is not 

 injured by the excreta of the preceding crop;' 

 and that it is not necessary ever at any time to 

 introduce fertilizing material into any soil for the 

 piirpose of increasing the amount of plant food in 

 that soil.^ 



In a public address before the American 

 Society of Agi'onomy upon the Chemical 

 Principles of Soil Classification, I can not 

 conscientiously omit a protest against this 

 teaching. That crop yields are increased 

 by application of plant-food materials is 

 universally and absolutely known, and this 

 fact is of coui'se admitted by all; but the 

 mere admission of this absolute fact does 

 not relieve in the least the serious menace 

 to American agriculture of the official 



* From page 64 of Bulletin 22 of the Bureau of 

 Soils, published in 1903. 



'From page 21 of Farmers' Bulletin 257, by 

 Milton Whitney, Chief of the Bureau of Soils. 

 published in 1906, 



' From the Hearings before the Committee on 

 Agriculture of the House of Eepresentatires, on 

 January 2S, 190S, in the committee's discussion 

 ■with leading members of the Bureau of Soils, 



teaching that such applications are entirely 

 unnecessary, that it is never necessary at 

 any time to introduce fertilizing material 

 into any soil for the purpose of increasing 

 the amount of plant food in that soil. 



Under this doctrine farmere are taught 

 to use, and to depend upon, any means or 

 method that will stimulate crop jnelds, 

 with no purpose or thought of maintaining 

 or increasing the plant food in the soil. 

 It is held that crop rotation is sufficient to 

 maintain the fertility of the soil, and that 

 powerful soil stimulants, such as quick- 

 lime and salt, will also accomplish this end. 

 On the other hand, the positive addition of 

 valuable plant food to the soil in systems 

 of permanent soil enrichment is distinctly 

 discouraged, such practise being de- 

 nounced as wholly unnecessary. Indeed, 

 farmere are strongly encouraged to rob 

 their land of its fertility to the greatest 

 possible extent and to make no return of 

 plant food to the soil. 



Furthermore, under this doctrine there is 

 every inducement to sell, for a trifle, not 

 only the million tons of phosphate rock 

 now being annually exported from this 

 country, but still larger and more ex- 

 haustive amounts of this tremendously 

 valuable and absolutely necessary natural 

 resource whose conservation is of tbe 

 gravest importance to the United States, 

 and of the most far-reaching consequence 

 to our national prosperity. 



Indeed, this is a matter of such vital con- 

 cern to this country, and especially to the 

 great agricultural states, that it can not 

 rightly be ignored; for, if these unsup- 

 ported theories are generally accepted by 

 the farmers of the United States, and if 

 the future, in harmony with all the past, 

 only proves that crop rotation will not 

 permanently maintain the fertility of the 

 soil, and that the use of soil stimulants only 

 leads to ultimate land ruin, then who shall 

 estimate what proportion of the farms that 



