OCTOBEB 21, 1910] 



SCIENCE 



533 



ture and have been for the last century 

 most carefully and elaborately planned, 

 the best that we can say for the use of arti- 

 ficial fertilizers is that, as agriculturists, 

 we are agreed that if we know the chemical 

 make up of a particular soil it is possible 

 to considerably enhance the cereal crop. 

 However, regardless of all the extensive 

 experiments, I think you will agree with 

 me that it is not possible to state a plan 

 purely of the nature of soil fertilization 

 that will hold with any regularity as to the 

 results on the crop for any extended area 

 of soil for any long period of years. This 

 is saying that the fertilizer question itself 

 largely remains an experiment in spite of 

 our best effort and that each farmer must 

 largely learn what to do for himself, which 

 is expecting much. 



It is evident from studying the best and 

 most extensive of these various fertilizer 

 experiments that aside from soil texture 

 and aside from differences in climate and 

 variation in atmospheric conditions dur- 

 ing different seasons there have been other 

 unknown causes which have largely vitiated 

 conclusions which may be drawn. This is 

 equally true as to conclusions which may 

 be drawn from long lines of carefully 

 planned crop rotation experiments. It is 

 one of these constant interfering influences 

 which I wish to bring to your considera- 

 tion, namelj% the introduction of parasitic 

 organisms which persist in the soil and 

 seed, eventually bringing about soil sick- 

 ness, such as has been recognized for cot- 

 ton, melons, potatoes and many garden 

 vegetables, alfalfa, clover and for flax. 

 After extended experience with cereal 

 crops of North Dakota and a rather close 

 observation of them in various parts of this 

 country, and of Europe, and from carefully 

 conducted experiments extending over a 

 period of twentj^ years directed upon the 

 soil and the crop, I am convinced that such 



parasitic interferences with crop produc- 

 tivity constitutes one of the chief causes of 

 the deterioration in quality and of yields 

 of wheat, oats, barley and flax. Further, I 

 would affirm, recognizing as I do that it is 

 possible to so crop the soil as to withdraw 

 chemical elements necessary to a complete 

 normal yield, that, in most cases, especially 

 in the northwest, this has not been done with 

 regard to cereal crops, and particularly 

 is this true of practically the entire area 

 for Minnesota and the Dakotas. I know 

 that the chemists and agriculturists have 

 reasoned, from field tests with fertilizers 

 and from laboratory analyses upon soil 

 and seed, that chemical depletion of the 

 soil is the chief cause of such deterioration, 

 but my experiments make it impossible for 

 me to accept the conclusion. There are 

 areas of North Dakota virgin soil, repre- 

 sented by our school lands which yet re- 

 main unplowed, surrounded by old wheat 

 areas which have been cropped for a num- 

 ber of years. These virgin lands when 

 broken do not now, as when the prairies 

 were first broken, produce wheat of num- 

 ber one quality, but often wheat of even 

 lower grade and quality than that of the 

 old lands immediately adjacent. 



I know that in farmers' institutes in the 

 various cereal-producing states, many 

 farmers have said something to the effect 

 that there must be a "change in climate," 

 complaining that they no longer are able 

 to produce wheat of the quality once pro- 

 duced, although they now work the land 

 much more carefully, having better ma- 

 chinery. Some of them practise essentially 

 aU of the doctrines of the experiment sta- 

 tions and farmers' institute workers, and 

 yet reap only low-grade grain for their 

 trouble. I know that these questions have 

 usually been answered by saying, "You 

 can not expect to continue reaping grain 

 of high quality." "Your constant meth- 



