858 



SCIENCE 



[N. S. Vol. XXVIII. No. 729 



Again, the bureau does contend that the soil 

 contains enough plant nutrients to support life 

 and give good crops, for it has been shown scien- 

 tifically in this country and abroad by many in- 

 vestigators in the past, and by many numerous 

 recent investigations, that all soils contain prac- 

 tically all the common rock-forming minerals. 

 Now, it is a principle of chemistry that when a 

 solvent is brought in contact with a substance, 

 that substance will go into solution until there is 

 a state of equilibrium between the quantity of 

 the substance outside and inside; in other words, 

 we get a saturated solution. If these rock-form- 

 ing minerals were in all soils we should have the 

 same solution in every soil, and that has been 

 shown to be the case. There are various varia- 

 tions, due to absorption, perhaps of the soil. In 

 the first place, I must ask you gentlemen to remem- 

 ber that the soil and the plant and the water in 

 the soil is moving. The soil grains are constantly 

 moving, and the solution in tne soil is constantly 

 moving, and the growing plant is constantly mov- 

 ing. If a plant stops for a moment it dies. The 

 soil solution can not stop for a moment, because 

 it has to be moving all the time. When water 

 falls on the soil part of it runs off the surface, 

 and part of it runs through the surface by gravi- 

 tation and comes out in the subsoil, and part of 

 it starts and rises as soon as we get sunlight on 

 the surface, and this part comes up in films over 

 and through the finer spaces, and is bringing with 

 it dissolved material from below. 



The water that falls and goes through down 

 and out goes rapidly through larger openings, and 

 gets very little of the soluble material, because it 

 is not long in contact with the soil grains. It 

 gets some by reason of the fact that, as we know, 

 our springs and rivers and wells are all soil solu- 

 tions and carry mineral matter. Now, water 

 rising by capillarity can not get very concentrated 

 because it gets saturated with the minerals, and 

 any excess that is contained in it is thrown out, 

 except in extreme conditions, as in the west, and 

 then we get alkali conditions; but under ordinary 

 humid conditions we can not have an excess of it, 

 and the soil solution is bringing materials from 

 below which the plant gets, and as a matter of 

 fact the most important discovery of the Bureau 

 of Soils in recent years is that plants are feeding 

 on material from the subsoils, far below where the 

 roots go. If this is true, and there are many 

 other arguments in the same line, it is absurd to 

 make an analysis of the surface soil and say that 

 is the soil that the plant is feeding on. It is not. 



The solution is changing around the plant roots, 

 and it is not the surface material alone on which 

 the plant is feeding. 



Now, I am sorry to say that I shall have to 

 make this personal, but in Illinois they have been 

 carrying on a long series of experiments and have 

 been making analyses of the soils, and they stated 

 that in the soils of Illinois there are just so many 

 pounds of phosphorus, and we know what a corn 

 crop will take out of the soil, and therefore we 

 can say that a corn crop will take out so much 

 each year, and these soils will last only a certain 

 number of years — I hesitate to say how many, I 

 do not recollect how many — I think about fifty 

 years. The work we carry on, which was largely 

 given in this bulletin which has been criticized, 

 absolutely overthrows that contention. The soil 

 is changing; it is constantly supplying the ma- 

 teria,l of the soil solution, and we know that soils 

 have lasted thousands and thousands of years, and 

 we have records of soils in India that have lasted 

 two thousand years, and we know they do not 

 wear out, and we gave the explanation why they 

 did not, and why the land did not become a sterile 

 waste, and it naturally aroused a feeling of oppo- 

 sition in the breast of this gentleman. 



The Chairman. When you say that all soils 

 contain all the elements of plant food, and there 

 is in those soils at all times a saturated solution 

 of which all these elemnts of plant food make a 

 part, do you not practically say that all soils have 

 all the plant food they need, and that it is at all 

 times available for the plant; or is it not avail- 

 able for the plant if it is in a saturated solution? 



Mr. Cameron. Certainly, if there is water 

 enough; if the soil is moist. 



The Chairman,. Is is not, therefore, a justi- 

 fiable inference from what you have said, that 

 there is all the time in all soils enough plant food 

 available for plant life? 



Mr. Cameron. True; perfectly true as regards 

 the mineral nutrients. 



The Chairman. Then I come back again to 

 the question. Why is it necessary, or is it in your 

 judgment necessary, ever at any time to introduce 

 fertilizing material into any soil for the purpose 

 of increasing the amount of plant food in that 

 soil? 



Mr. Cameron. Not in my judgment. 



The Chairman. Then in your judgment the 

 only reason for the introduction of fertilizers is 

 for the antitoxic effect or the mechanical effect 

 they may have on the soil. 



Mr. Cameron. Mainly that, but there are prob- 



