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SCIENCE 



[N. S. Vol. XXXVIII. No. 973 



not now have available as to wheat and 

 cereal cropping. That he succeeds as well 

 as he does is proof positive that cereals are 

 sturdy crops. Wheat, for example, is 

 among those crops which man has always 

 had with him since he became reasonably 

 intelligent, and it is probable that only the 

 survival of the fittest, acting under the 

 many interfering unintelligent activities of 

 man, now accounts for the fact that our 

 wheat yields remain as high per acre as 

 they do. 



The writer is one of those who believes 

 that disease, as a factor, has been one of 

 the madn agents of elimination, directing 

 the survival of the fittest among cultivated 

 plants as amo7ig peoples themselves. I 

 also believe that when we get our people to 

 understand this problem, the question of 

 sanitation, both our home life and farm 

 cropping work will have a new meaning of 

 very great importance to the public. 



The Problem not Alone an American 

 One. — That the problem of deteriorated 

 yields in quality in cereals is not alone an 

 American problem is evident from the lit- 

 erature now appearing in England and 

 other European countries, especially, at 

 present emanating from the Rothamsted 

 farm. By our noted American agricul- 

 turists we have been almost led to believe 

 that they had no wheat problems at the 

 Rothamsted farm. All were settled by 

 well-worked-out theories of soil fertiliza- 

 tion and crop rotation. Our farmers have 

 been told that, if they would do likewise 

 (which is an essential impossibility under 

 present farm conditions) they would have 

 no trouble in boosting our annual yield to 

 25 or 30 bushels per acre. 



When it has been needed to drive our 

 farmers a little harder, we have not hesi- 

 tated to say to them, "Look at the wheat 

 yields of England, Prance and Germany," 

 apparently all oblivious of certain great 



differences in farm conditions existing 

 there which do not exist and which can not 

 exist here for many years to come, and to 

 the further fact that in proportion to their 

 intensified conditions of agriculture, they 

 have the same great proportionate varia- 

 tions in yearly success. Their grains show 

 the same signs of deterioration and they 

 have the same uncertainty that the crop 

 will pay for the labors and money ex- 

 pended. The writer now knows that their 

 troubles are primarily the same as ours. 

 If we are to judge from the reports from 

 the Rothamsted Farm, they have no clearer 

 explanation of the wherefor of the ill ef- 

 fects of continuous cropping than has been 

 given by our own agriculturists who have 

 but largely repeated old explanations. 



Theories. — There are many theories as 

 to the causes underlying these irregulari- 

 ties as to cereal-cropping under special 

 methods ; especially as to the causes under- 

 lying apparent soil depletion and wheat 

 deterioration. 



1. The Lost Fertility Theory: For ages 

 the farmer has known that proper food 

 prevents starvation, that hay and grain 

 make the fat horse, etc., and from experi- 

 ence knows that what he calls a fertile 

 black, mellow, tillable soil commonly makes 

 strong plants; that farm manures gen- 

 erally tend to give crop increase, though 

 in the case of cereals there is no certainty 

 of this. There may be increased yields, 

 with vital deterioration in quality of seed 

 produced. He has, however, always lent a 

 willing ear to the fertility doctrine and has 

 willingly looked to the chemist to tell him 

 what to do, what to eat, drink, and what to 

 feed his stock. From this vantage point 

 the chemist has from the first had slight 

 trouble in dictating from the laboratory 

 the measure of soil fertility, but I think I 

 am safe in saying that he never has been 

 able to explain why fertile soils and nor- 



