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THURSDAY, NOVEMBER 30, 10916. 
AMERICAN BOOKS ON AGRICULTURE. 
(1) Field and Laboratory Studies of Soils. An 
Elementary Manual for Students of Agriculture. 
By Prof. A. G. McCall. Pp. viiit+77. (New 
York: John Wiley and Sons, Inc.; London: 
Chapman and Hall, Ltd., 1915.) Price 2s. 6d. 
net. 
(2) The Principles of Plant Culture. A Text-book 
for Beginners in Agriculture and Horticulture. 
By the late E. S. Goff. Revised by J. G. Moore 
and L. R. Jones. Eighth edition. Pp. xxiii+ 
295. (New York: The Macmillan Company; 
London: Macmillan and Co., Ltd., 1916.) 
Price 5s. 6d. net. 
(3) The Principles of Agronomy. A Text-book of 
Crop Production for High Schools and Short 
Courses in Agricultural Colleges. By Prof. F. S. 
Harris and G. Stewart. Pp. xvi+451. (New 
York: The Macmillan Company; London: 
Macmillan and Co., Ltd., 1915.) Price 6s. 
net. 
(4) The Marketing of Farm Products. By Prof. 
L. D. H. Weld. Pp. xiv+483. (New York: 
The Macmillan Company; London: Macmillan 
and Co., Ltd., 1916.) Price 6s. 6d. net. 
(2) HE first book on the list is a little labora- 
tory manual for the study of soils by 
Prof. McCall, of the Ohio State University. The 
appliances needed are simple, and the exercises 
are all within the scope of any reasonably intelli- 
gent pupil. As usual in American books, physical 
properties attract considerable attention, and 
most of the exercises are concerned with the 
water relationships of soils. Only two at the 
end deal with lime, and none of them with the 
biochemical processes, such as nitrification, that 
play so important a part in soil fertility. But 
within the limits the author has set he has given 
an interesting course of experiments which the 
teacher might well use in the study of soils. 
(2) This book first appeared in 1896, and has 
been so successful that it is now in its eighth 
edition; it may fairly claim, therefore, to be a 
standard text-book on the other side of the 
Atlantic; one of the revisers is professor of plant 
pathology and the other professor of horti- 
culture in the University of Wisconsin. The 
book was originally intended for agricultural 
students who had had no preliminary training in 
botany, and it is written in a way which will 
appeal to them, all the illustrations being taken 
from agricultural or horticultural practice. Other 
authors, both in England and America, have 
shown that the method is feasible, and that the 
farm and garden can be made to furnish all the 
material and illustrations wanted for a very useful 
course of botany. The drawback is the great 
difficulty of keeping within some sort of limits, 
and there is a great temptation, which the authors 
have not been altogether able to resist, to wander 
NO. 2457, VOL. 98] 
into other fields. This has resulted in several 
rather surprising errors. On both p. 146 and 
p- 148 the authors refer to rain and snow as con- 
tributing useful amounts of nitrogenous sub- 
stances to the soil. This view was formerly held 
by chemists, but has long been given up by them. 
Again, wood ashes are stated to be a commercial 
source of phosphates; surely the authors must 
mean potassium. ‘There is some confusion between 
“potash” and “potassium ” which ought to have 
been put right before now: “Potassium is used 
by plants in the form of potash, i.e. potassium 
combined with oxygen. Potash exists in the soil 
mainly in combination with chlorin (chlorid or 
muriate of potash), with sulfuric acid (sulfate of 
potash), or with nitric acid (nitrate of potash).” 
Now, apart from the fact that the statements are 
incorrect, most of the potassium being there as 
complex silicates, and little, if any, as chloride 
or sulphate, it is misleading to say that muriate 
of potash is a combination of chlorine and potash, 
and that potash is a combination of potassium and 
oxygen. Old terms like muriate of potash still 
survive in the fertiliser trade, and may perhaps 
be defended on the ground that they denote a 
certain trade product; but in explaining them to 
the student it only adds to the difficulty to use old 
chemical nomenclature. Much of this chapter 
might well have been omitted. 
(3) Agronomy is a new word for the English 
language, introduced some years ago in America 
to stand for field husbandry, but already, accord- 
ing to the authors, it is beginning to be used 
rather loosely. It covers plant growth and soil 
management, a branch of knowledge which, as 
experience has shown, can be brought into a com- 
pact subject and dealt with by ordinary scientific 
methods. But, as has often been remarked, there 
is a great temptation to wander when a man is 
dealing with a field or garden subject, and it has 
become almost a convention that books on “‘agro- 
nomy ” should include chapters on botany, geology, 
engineering, bacteriology, and sometimes other 
subjects as well. Obviously this leads to very 
unequal treatment, and we cannot help thinking 
that the time has come when the “agronomist ” 
should think out his position a little more clearly, 
give a definite meaning to his name, agree to 
leave out chapters on other things, and confine 
himself to his own subject, which is already big 
enough. If we do this with the book before us 
we get an interesting account of crop production in 
the United States, obviously written by men who 
know what they are talking about. The illus- 
trations in particular are to be commended, some 
of those dealing with field conditions being un- 
usually good. 
(4) The last book on the list deals with a very 
old subject, which, however, is only just beginning 
to get a literature of its own. The author 
acknowledges in the preface his indebtedness to 
the authorities of the University of Minnesota, 
who were sufficiently far-seeing to allot funds for 
a scientific investigation into the marketing of 
farm produce. The result is very satisfactory, 
O 
