Decembee 18, 1908] 



SCIENCE 



859 



ably other functions of fertilizers that we know 

 comparatively little about. We know that certain 

 kinds of life, bacteria, molds, can grow in certain 

 solutions of salts, and can not in others. It may 

 be that fertilizers affect them. But all that is an 

 unexplored field, and little is known about it. . . . 

 If you will allow me to say one more word about 

 fertilizers: What are fertilizers! What are the 

 characteristics that a substance must have in order 

 to be a fertilizer? It must be obtainable in large 

 quantities. It must also be cheap. Now, the sub- 

 stances which are used as fertilizers in fertilizing 

 material are substances which can be obtained in 

 large quantities. They are substances, and are 

 the only substances, which we can get hold of that 

 we can get in large quantities that we can get 

 cheap, and with one exception, that is, sodium 

 chloride — common salt. It has not been much 

 used as a fertilizer, because it has not any so- 

 called plant food in it; and yet it has been used 

 in quite a large number of experiments on quite 

 a large scale, and wherever it has been used it has 

 generally been found to be quite a good fertilizer. 

 In the investigations of the bureau we have used 

 pyrogallol. It contains no plant food, but carbon, 

 hydrogen and oxygen, yet, nevertheless, it is a 

 powerful fertilizer; but it can not be obtained 

 cheaply. It is worth over $2 a pound, and nobody 

 would think of recommending it as a fertilizer. 



Mr. Pollard. Is that theory about all soils 

 containing all the necessary constituents of plant 

 food generally held by all scientists? 



Mr. Cameron. It is accepted by the physical 

 chemists, and by the majority of plant physiolo- 

 gists, and by a large percentage of the agricultural 

 investigators. 



Mr. Pollard. Throughout the country? 



Mr. Cameron. Throughout this country and 

 Europe; more in Europe than in this country. 

 We have received far more recognition abroad 

 than in this country, but the acceptance of it is 

 growing very much more rapidly. Within the last 

 two years several of us have lectured at the agri- 

 cultural colleges and have explained these views, 

 and have shown that the criticism which came to 

 Bulletin No. 22, of which I have spoken, was 

 largely incorrect, founded on false premises, and 

 as a result of that we have a large mass of evi- 

 dence in the form of letters, and other evidence 

 in the fact that a number of agricultural schools 

 are now teaching this, and are using our bulletins 

 as text-books, that these views are accepted every- 

 where. 



Mr. Pollard. You have reached a point where 



there is no question about the soundness of that 

 view? 



Mr. Cameron. I feel absolutely sure of it, and 

 I think there is no question but that 90 per cent, 

 of the scientific men^ of this country would back 

 that up. 



Mr. Pollard. The reason I asked this question 

 is that it seems to me that all of the bureaus — 

 I do not say it with reference to this bureau in 

 particular, but all the bureaus of the various 

 departments at Washington — ought to be very 

 careful about sending out matter of that kind 

 unless they are sure, unless they have proven 

 their ground, because it is likely to mislead and 

 make trouble. That was the reason I asked the 

 question. 



Mr. Cameron. There has not been a publica- 

 tion on the subject of soil fertility going out from 

 the Bureau of Soils — and I think I can speak 

 advisedly, for every one has gone through my 

 hands — in which we did not have the experimental 

 proof long before the publication went out, and 

 that this is being recognized I think I can claim 

 by the fact that a number of agricultural colleges 

 in the country are using our bulletins as text- 

 books. I have recently come from a lecture trip 

 extending from Louisiana to Michigan, and I 

 found everywhere that this was being taught, 

 and, as I say, our publications are being used for 

 text-books. (Pp. 445-449.) 



Here we have some very plain, concise, 

 and authentic statements of the teaching 

 of the United States Bureau of Soils con- 

 cerning the chemical principles of soil 

 fertility; and these statements are in har- 

 mony with the teaching in past years. 

 Thus on page 64 of Bulletin 22 of the 

 Bureau of Soils, published in 1903, we 

 read: 



That practically all soils contain sufiicient plant 

 food for good yields, . . . that this supply will be 

 indefinitely maintained. 



And on page 59 in the same bulletin 

 were published the following statements : 



In truck soils of the Atlantic coast, when 10 

 or 15 tons of stable manure are annually applied 



- See report adopted by the Norfolk Convention 

 (1907), of the committee of seven on the presi- 

 dent's address before the Association of Official 

 Agricultural Chemists in 1906, published as Illi- 

 nois Circular 105. 



