98 
received as to the immediately available phosphate and potash." It is even asserted « 
that " on lines similar to those followed in this paper (from the Bureau of Chemistry) 
it would be possible to establish solvent conditions as representing the feeding ability 
of any plant, whereupon the desired crop would be specified when the soil sample 
is forwarded for analysis." 
Following this contribution, and in almost absolute disagreement with it, has 
appeared Bureau of Soils Bulletin No. 22, of the U. S. Department of Agriculture, 
on "The Chemistry of the Soil as Related to Crop production," in which it is 
asserted & with confidence "that practically all soils contain sufficient plant food 
for good crop yields, that this supply will be indefinitely maintained, and that the 
actual yield of plants adapted to the soil depends mainly, under favorable climatic 
conditions, upon the cultural methods and suitable crop rotation." 
It is further asserted ^ that this is " a conclusion strictly in accord with the expe- 
rience of good farm practice in all countries, and that a chemical analysis of a soil, 
even by these extremely delicate and sensitive methods, will in itself give no indica- 
tion of the fertility of this soil or of the probable yield of a crop, and it seems prob- 
able that this can only be determined, if at all, by physical methods, as it lies in the 
domain of soil physics." 
Again I feel compelled to ask, "Where are we?" Shall we analyze our soils 
chemically every spring before seeding time? Or shall we analyze them not at all? 
Shall we continue to use commercial fertilizers and farm manure for any other pur- 
pose than physical effect? Shall we continue our efforts to encourage the nitrogen- 
gathering bacteria to gather nitrogen? Or shall we simply rotate and cultivate? 
It may assist us in solving some of these soil problems if we keep in mind the 
fact that the soil serves the plant in two different ways, or, we may say, the soil has 
two distinct offices, or functions, in connection with crop production: First, the soil 
furnishes a home for the plant, a mere lodging place, in which the seed germinates 
and the plant "lives and has its being; " second, the soil furnishes food, or nourish- 
ment, for the growth, development, and maturing of the plant. 
Is the soil hard and compact and almost impenetrable to plant roots, or is it loose 
and porous? Is its texture fine and plastic, medium and friable, or coarse and granu- 
lar? Does it readily absorb and retain moisture, resist drought, and permit the free 
movement of water through it and thus facilitate drainage? Or is it almost impervi- 
ous to water, nonabsorbent, and nonretentive of moisture? These questions deal with 
the first function of the soil — that is, with its physical properties, which determine 
whether the soil is a suitable home for the plant. 
The second function of the soil is to feed the plant, to supply nourishment absolutely 
required for the growth and maturity of the crop. Does the soil contain a sufficient 
store of nitrogen, phosphorus, potassium, and other required elements of plant food, 
and will a sufficient quantity of these be made available during the progress of the 
season to meet the needs of the growing crop? Can we add to the store of nitrogen 
in the soil, or furnish it direct to the growing plant, from the uncombined nitrogen 
contained in the air by bio-chemical means? Can we supply or supplement the soil's 
supply of plant food by applications of farm manure or other fertilizers? Can we 
hasten the disintegration of soil particles and the consequent liberation of plant food 
from the soil by increasing the amount of decaying organic matter in the soil or by 
applications of lime or other materials? These questions deal with the feeding or 
nourishing of plants. This is soil chemistry, the other is soil physics, and neither 
can truthfully say to the other, "I have no need of thee." 
We have in Illinois an area of land whose principal type of soil contains only 600 
pounds of phosphorus per acre in the plowed soil to a depth of 7 inches. A good 
crop of corn, such as we commonly produce on the best soils in the State, removes 
from the soil 23 pounds of phosphorus per acre. Twenty-five or thirty good crops 
would actually remove from the soil as much phosphorus as is contained in this 
plowed soil, and the plowed soil is considerably richer in phosphorus than the soil 
below it. 
It is mathematically impossible that the "supply will be indefinitely maintained," 
if good crops should be removed from this land for any considerable number of years. 
The question is asked, if this is not a very small area of abnormal soil. It is true that 
this area is a fraction of the State of Illinois, but, nevertheless, it is large enough to 
make eleven States the size of Rhode Island. In former years this part of Illinois 
supplied sufficient com to the rest of the State so that it was nicknamed " Egypt," 
and it is still popularly known by that name. 
We have another area comprising seven counties whose principal type of soil, after 
« Jour. Amer. Chem. Soc, 24 (1902), p. 113. 
6 U. S. Dept. Agr., Bureau of Soils Bui. 22, p. 64. 
