JANUARY. 19,1912] . 
peated annual applications may result in 
the most marked soil improvement, render- 
ing successful the cultivation of a whole 
series of crops where they could not be 
grown successively before. The same treat- 
ment, even for a long series of years, may 
still fail to correct the existing soil con- 
ditions enough for other groups of plants. 
The continued use of nitrate of soda on 
another soil may cause it to become 
puddled until it is rendered practically 
unfit to be a habitat for most agricul- 
tural plants. For certain plants, such 
as the radish and beet, the residual 
sodium from nitrate of soda may per- 
form valuable physiological functions 
which would be lacking, or of slight im- 
portance, in connection with certain other 
plants. Raw rock phosphate may be valu- 
able as a fertilizer on the black soils of the 
Illinois corn-belt and for crops usually 
grown there, but for the light sandy soils 
of the Atlantic coast and for certain truck- 
ing crops its use at prevailing prices could 
perhaps not be recommended. To add to 
this complexity certain text-books proscribe 
the use of lime with superphosphates, or on 
soils where undissolved phosphates are to 
be used, and yet there may be soils on 
which liming is essential to the most eco- 
nomical use of each. It is, in fact, not 
enough that the agronomist should bear in 
mind and master all of these details, but 
now he is called upon to consider the spe- 
cifie requirements for lime and other sub- 
stances, of hundreds of varieties of plants. 
He must also consider the alleged toxic 
root excreta and methods for rendering 
them innocuous, and he must take cogni- 
zance of the catalytic action of manganese 
and other elements not heretofore grouped 
in the galaxy of fertilizers and soil amend- 
ments. He must now consider the effect of 
legumes and other plants upon those grow- 
ing in association with them and the effect 
SCIENCE 
83 
of given crops upon those which follow: 
The whole question of maintaining condi- 
tions favorable to nitrification is of prime 
importance in certain sections of the 
United States, and in this connection chem- 
istry is again the handmaid of agronomy; 
yet in certain of the semi-arid regions of 
the middle west excessive nitrification is 
said to have become a scourge which is 
wiping out many of the most promising 
orchard industries. It must be evident 
that the agronomist must therefore be 
something of a climatologist, for in certain 
of these features the weather conditions 
are the chief governing factors. 
The successful agronomist must also 
deal effectively with a host of plant para- 
sites which may attack the roots, the base 
of the stems, or the other aerial parts of 
the plants. Some of these may be killed by 
poisons, whereas others can not. Even the 
sucking and boring insects furnish a prob- 
lem in themselves, long after the entomol- 
ogist has determined the essential features 
of their life history. Just as ‘‘every ani- 
mal has its fleas and these have fleas to bite 
’em,’’ so the plants have their many ani- 
mal and fungus parasites, with which the 
agronomist is forced to deal. 
Since the soil is one of the chief con- 
cerns of the agronomist, and it is known to 
be teeming with many forms of microscopic 
life of beneficial or injurious character, it 
is important to take cognizance of the pos- 
sible effect upon this life of the various 
kinds of organic matter and of fertilizers 
which may be introduced into the soil from 
time to time. 
Notwithstanding the recent assertion 
that practically the same minerals are 
found im all soils, that plants feed from 
very weak solutions, and that the soil solu- 
tion is being continually renewed, we can- 
not complacently fold our arms and watch 
the workings of the divine providence in 
