230 



SCIENCE 



[N. S. Vol. XXXIII. No. 841 



2. It is a common experience ttat as soon as 

 a particular cereal crop has become general, 

 and that usually follows in a very few years, 

 a marked deterioration, both in yield and 

 quality, sets in. The crop, except in special 

 years, and under rare exceptions of special 

 farming, seldom again reaches the same high 

 grade of yield and quality. Indeed, the yield 

 generally falls to the average for the country, 

 above which it can be raised again only 

 through exceptional methods; and, to the 

 chagrin of many of our most able agricultural 

 educators, no philosophy of cropping or land 

 improvement seems to give the farmer the 

 desired results with any regularity, year by 

 year, for any long period of time. The crop 

 or variety once a favorite in a locality usually 

 has a short life and finally gives place to a 

 real change in agriculture, seldom, if ever, to 

 regain its place. 



3. Not many theories have been advanced 

 to account for these results. The chemist and 

 his followers have usually directed thought in 

 the matter, and agriculturists, generally, have 

 taken the chemist's dictum that marked 

 changes have occurred in the balance of plant 

 food relations of the soil, thus accounting for 

 the rapid first deterioration of the crop 

 through chemical losses noticed in the soil. 

 Thus if a lack of proteid is found in the grain 

 of wheat and a loss of nitrogen is observed in 

 the soil, it has been reasoned, without founda- 

 tion, I think, that the noticed chemical loss 

 in the soil is necessarily the cause of the defi- 

 ciency in the kernel. When our chemical 

 friends have, by their own analysis, discovered 

 that there is, however, sufficient strength of 

 soil solution regarding all known necessary 

 chemical elements to support a crop on a par- 

 ticular field, the failure to reach crop quality 

 has been quite uniformly attributed, by them 

 and the rest of us, to slovenly methods of 

 farming, poor physical texture of the soil, 

 degenerated seed, etc. 



Any other special theories which have been 

 advanced in particular to account for the facts 

 have all been strongly influenced by the recog- 

 nized fact that soil can be impoverished, re- 



duced in its chemical strength. The Whitney 

 toxine theory would appear to be only a reflec- 

 tion of this troubled state of the chemical and 

 physical mind, associated with a desire to- 

 show that a complex plant growing in the 

 soil and air acts upon the soil after the man- 

 ner of a bacterial culture in a test tube. That 

 I may not be misunderstood, I may say that 

 I believe that certain soils may be exhausted 

 chemically by cropping methods; that I think 

 it is wholly possible that the excrementia of 

 plants under rather constant cropping may 

 have an analogous effect upon the crop to 

 that noted in bacterial cultures upon the sub- 

 stratum, but that after several years of care- 

 ful trials upon wheat and flax, both under 

 culture house conditions, and under carefully 

 planned plot trials, I have been unable to 

 find any point which would tend to substan- 

 tiate the toxine theory. Nevertheless, the 

 contention of Mr. Whitney, that the soils of 

 cereal regions are not particularly exhausted 

 is, in my belief, much nearer to the truth than 

 the contention of the chemists and others that 

 the deteriorated yields and qualities of wheat 

 and other cereals are due to chemical exhaus- 

 tion, and especially to nitrogenous exhaus- 

 tion; for neither the chemists' exhaustion 

 theory nor the toxine theory can account, to 

 my satisfaction, for the failure of virgin soils 

 to produce the yields characteristic of that 

 region when such cereal cropping was first 

 introduced. It is a fact that such lands are 

 quite as liable to give the crop characteristic 

 of the old, so-called, worn-out lands, as do the 

 older lands. It is not the uniform failure of 

 the particular crop which causes it to be 

 dropped by a farming community, for it is 

 evident that all of the lands of a community 

 can not be so depleted. It is the general un- 

 certainty of giving results, year by year, which 

 results in abandoning or ceasing to expect a 

 proper yield. It is evident from the forego- 

 ing considerations that there are constant in- 

 terfering agencies at work in cereal cropping 

 regions which have not as yet been properly 

 taken into consideration, for, even under the 

 best weather conditions possible, essentially 

 the same weather conditions which in a new 



