Sept. 1, 1900.] THE TROriCAL 
AGRICULTURIST. 
197 
THE PHYSICAL PROPERTIE OF SOIL.* 
The investigatiou of the physical properties of the 
soil, its so called mechanical analysis into particles 
of various grades of fineness, upon which depends 
to a large extent ihe amenability of the soil to 
cultivation and its Bcwer of supplying water to crop?, 
has of late vears re'oeived greater attention than the 
chemical methods of examining the soil. Whether 
too much v/as expected from the chemist, or whether 
the method itself was essentially at fault, certainly 
the old way of determining the gross proportion of 
the principal elements of plant nutrition— nitrogen, 
potash, phosphoric acid, lime— present in the soi), 
has often failed to yield information of practical 
value to the cultivator; hence the German investij 
pators, led by Professor Octh, of Berlin, in analyt- 
ical matters, and by Professor VYolluy, of Vienna, 
as regards -soil physics, have been more and more 
concentrating their attention on the physical side 
of the question. The example of the Germans has 
been followed and extended by the yonuger school 
of American investigators in the various agricultural 
experiment stations that are so liberally scattered 
over the United States, with the result that the 
experimental woik carried out in the laboratory and 
in the field on this subject by Hilgard, Osborne, 
King, Whitoey, and others, probably by this time 
exceeds in amount the whole of the continental work. 
Jn Enf'land, but little research of the kind has been 
done, hence the late Sibthorpean Professor has 
thought it well to prepare— first, for a lecture course 
at Oxford, and now in book form— a summary of 
the more important recent investigations, chiefly 
American, on the physics of the soil, with the view 
of inducing our younger agricultural teachers to pay 
a little more attention to questions of cultivation, 
and a little less to artificial manures. Professor 
Warrington's bock cannot fail to be of service to 
the serious student of agriculture; it brings together 
a mass of information that was scattered throiigh 
scientific periodicals of various dates and countries, 
whereas hitherto the only place where the English 
reader could find any general view of the sub.jeot 
was in that excellent little book The Soil, published 
by Professor King, of Wisconsin, in 1895. 
Soil physics, with which the book before us deals 
is briefiy the study of the laws of tilth, of the acts 
of hu;.bandrv as affecting the texture and water con- 
test of the soil ; and as Professor Waringlon main- 
tains at the outset, this question of tillage and manage- 
ment of the land is of far greater practical importance 
than manuring. Every farmer or gardener is well 
aware that one mis-timed cultivation may easily ruin 
all chance of getting a satisfactory crop ; indeed, 
oil some soils a single ill-judged operation may throw 
the land into a bad state that can never be rectifiea 
during the whole rotation, until the land goes down 
to grass again. -i u • ■ 4. 
The only question is, whether the soil physicist 
will be able to provide much more practical assist- 
ance to the cultivator than the chemist has in the 
past, and we think Professor Warrington rather 
exaggerates in its turn the value of a physical 
analysis of a soil; in the present state of our 
knowledge we doubt if move can be predicted fvom 
it than information of the most general kind, which 
any experienced man would gain by merely walking 
over and handling the land on one or two occasi'Ti^. 
Professor Warington in this connection draws atten- 
tion to some of Hilgard's examinations of Mississippi 
soils, and Whitney's of Maryland soils; mechanical 
' analvses are given of land suitable for market garden 
work, Tobacco, Wheat, and grass, and of these he 
says : '• With these differences in physical consti- 
tution, the agricultural value of soils, and their 
suitability for'the growth of different crops plainly 
connected. We could hardly have a better illustra- 
tion of the great influence of physical structure and 
* Lectures on some of the 'Physical Properties of 
Soil. By Professor R. Warington (Oxford, Clarendoa 
Press, 1900. 
24A 
of the extent to which tliis can be revealed by the 
methods of mechanical analysis." The example givert 
hardly bears out this opinion, the classification 
('market-garden laud. Tobacco, Wheat, and grass- 
land) is of a very general kind ; neither here, nor 
in any other American work, is there a correlation 
of the soil analyses wdth those subtle but real differ- 
ences in the working of particular soils which the 
cultivator learns by experience ; indeed, we question 
if the American farmer is sufficiently practised in 
the finer arts of tillage and management of land 
to supply the analyst with the information necessary 
for the interpretation of the experimental results. 
Such classification as soil analysis gives may be of 
service to the pioneer opening up new districts, or 
introducing more specialised crops in what has been 
a roughly cultivated region; but in a country like 
ours, where there exists a body of actual experience 
about the behaviour of almost every individual field, 
the soil physicist has still to learn from, and not 
to teach, the cultivator. 
Our own experience would tend to show that the . 
problems of soil-texture are too complex to be solved 
by a consideration alone of the sizes of soil particles. 
We have found, for example, that soil samples from 
almost contiguous fields on a well-marked tract of 
land that possessed special cultural characteristics, 
yet would vary by more than cent, per cent, in their 
proportions o£ sand and clay, although there were 
no differences in the behaviour of the land to tally 
with these variations in mechanical composition. 
The fiest chapter of Professor Warington's book 
is devoted to a consideration of the methods of 
mechanical analysis. On the whole, he appears to 
give the preference to the process of grading the 
soil particles by means of water running at various 
speeds, which has been brought to the greatest 
refinement of Hilgard ; and Schloesing's decantation 
method, which is practised in France and Belgium, 
is dismissed as crude. But, as Petermann has pointed 
out in his book on. the Analyses of [?elgian Soils,* 
the alkaline solution employed in Schloesing's method 
ensures that the material estimated as " clay " shall 
correspond very fairly in its chemical nature to pore 
clay, i.e., hydrated silicate of alumina, and with this 
our experience agrees ; whereas the " clay " separated 
by the other methods is much more largely mixed 
with sand particles of excessive fineness. Of course, 
Hilgard's method is of great refinement in grading 
the particles of sand. It may be questioned, how- 
ever, if this refinement is not something of a snare, 
tempting the observer to consider his work more 
accurate than is possible from the nature of the 
material ; for our observations seem to show that in 
a country like England, of a markedly undulating 
surface, that has long been under cultivation, the 
mechanical composition of the soil varies enormously, 
even from field to field on the same type of land. 
Chapters II. and III. deal with the relation of 
the soil to water, the movements of water within 
the .soil as affected by cultural operations like 
ploughing, hoeing, mulching, and rolling — this ia 
the part of the book that will particularly appeal 
to the gardener, for here he will find explained the 
pi inciples that underlie much of his practice in the 
jiiiinagement of the land, and a proper appreciation 
of these principles cannot but quicken his observa- 
tion when at work, and his powers of dealing with 
a novel situation. The discussion is plentifully 
illustrated by accounts of actual experiments, mostly 
carried out in America, and very skilfully devised 
to illuminate the point at isgue ; while, as he reads, 
the thoughtful gardener or farmer will be able to 
supply a running comment from his own experience. 
The last chapter of the book deals with the 
movement of salts in tJie soil, with the composition 
of drainage waters, and the loss of plant food that 
thereby results, and particularly with the sterility 
arising from the accumulation of saline residues in 
* Eecherches de Chimie, &c., Appliquees &, rAgri» 
euUure (Bruxelles), 1898. 
