62 
THIRTEENTH REPORT. 
or ratio of water content to air space. Any one of these may, in a par- 
ticular case, be a factor of even predominating influence, but always the 
crop is determined by a large number of factors, and it is not rational 
to describe any one of these various contributing factors in crop pro- 
duction as a theory of fertility or a theory of soil management. 
The increase of knowledge concerning the chemical processes taking 
place in soils, the function of water ais a great reactive agent in prepar- 
ing the mineral constituents for the easy assimilation of plants, the 
translocation of such materials from subsoil to surface soil, the part that 
other mineral constituents than those recognized as plant foods may 
and probably do play in affecting quantity and quality of product, the 
chemical and physical effects of organic substances which are now being 
separated and recognized by definite scientific criteria, the biological 
activities, the various types of bacteria or their antagonists, the pro- 
tozoa, all this information in each and every case comes back practi- 
cally to the question of soil management. How they are controlled by 
tillage, by rotation, by fertilizers; liow a just balance between these fac- 
tors is to be sought for the production of a crop of given quality or given 
mass or volume. Such an adjustment must always be a matter of judg- 
ment. Therefore soil management is an art, dependent upon investiga- 
tions of a large group of sciences, which we can call for convenience, 
agricultural science. 
In the practice of this art the labors will be much lightened if the 
expert has an intelligent clientele. No effort should be spared to bring 
the modern concept of the soil and its relation to crop production to every 
farmer in the community. It will be found more interesting and more 
reasonable than the stereotyped views which have preceded it and so 
long maintained their sway. And with an assimilation of these ideas 
will come a mutual understanding between the farmer and the expert. 
With a recognition of the fact that the soil is an individual and must be 
treated as such will come an effort on the part of the farmer to adjust 
his management to it, and enable him to put before the expert a clearer 
picture and to formulate a cleaner question when difficulties are en- 
countered. Nothing is more trying to the soil investigator than to be 
sent a sample of soil and to be asked to analyze it and tell what fertilizer 
it needs and what crops will grow on it. But yet the question is a fair 
one under past conditions and the expert has no one to blame but him- 
self for the. fact that the layman does not know that no stereotyped 
method of examination, physical, chemical, or biological can possibly tell 
what a dynamic system will do under a specific but dynamic environment. 
Quite recently there has been a great public awakening in this country, 
a prominent feature of which is a greater appreciation of the importance 
of the nation's soils. The time is ripe for the minds of the people are 
in a receptive mood for the newer knowledge which such gatherings as 
this are making available. Surely the farmer will take a keener and more 
intelligent interest in his soil when you show him that instead of being 
a dead, inert mass of rock and plant debris, it is scarcely less active than 
his stock; that changes are going on in it. all the time, changes which 
are as susceptible to control as the feeding and working of his stock. 
That each field is an individual which he must continually study, coax, 
repress or force as he would his growing herd. The true soil manage- 
ment absolutely precludes monotony, for never twice does the same field, 
