ipo?] Garden, Field, and Forest of the Nation. 59 
might change the fertility of their soil by changing its texture. 
In examining into the improved conditions of agriculture in 
the dune districts of the Jutland Peninsula a number of 
years ago, I found that the farmers of that country attri- 
buted their prosperity wholly to the suggestions made to their 
fathers and grandfathers by Liebig who went to Denmark to 
study moving sands; but I have not been able to find that he 
ever published anything on the subject. 
But the dream of Liebig is being realized, and the study of 
soils is enlisting the closest attention of the chemist, the 
geologist, the mineralogist, the bacteriologist, the botanist, — 
a relatively small but powerful coterie of men who are the 
investigators and interpreters of modern agriculture. The 
chemist has found the essential plant foods, the geologist has 
noted the natural distribution of vegetation with relation to 
rocks both as to composition and structure, the mineralo- 
gist and geologist have studied the rock-making minerals in 
relation to their available plant-foods, the bacteriologist has 
shown us that certain living organisms in the soil are of 
enormous importance to every man who raises food for man 
and beast, the botanist has busied himself with breeding 
certain plants adapted to certain soils. “Knowledge is now 
no more a fountain sealed.” The farmer of to-day may, nay 
he must, come up to his calling “as fully equipped for service 
as the lawyer, the editor, the doctor, the captain of industry; 
for the curious fact has developed that the calling in which 
the unlettered and untrained man was once supposed to have 
as good a chance as the educated one, is now the calling in 
which wide and varied knowledge is almost as imperative as 
in almost any other known among men.” 
Of the more than seventy elements that make up the crust 
of the earth only about a dozen are essential to successful 
agriculture and practically all soils contain these in one 
form or another. Only four of the twelve — nitrogen, phos- 
phorus, potassium, and calcium — are liable to be lacking in 
