THE VEGETATION OF SALINE AND ALKALI LANDS.
_Marine Saline Lands._—While the saline alluvial lands of the sea-coast
differ both in their mode of origin and in their nature from the alkali
soils or “terrestrial saline lands,” as they have been called in
Europe, their vegetation has in many respects a common character. Not
only is there much similarity, sometimes even identity, in the kinds
of plants inhabiting these lands, but their saline ingredients induce
certain changes of form and structure in plants not properly “saline”
but more or less tolerant of soluble salts, by which the saline or
alkali character of the lands may be recognized.
Just as in the case of lime we must distinguish between the plants
definitely repelled by a large amount of this substance in the soil
(calcifuge), while others prefer the soils in which lime is abundant
(calciphile), and still others appear to be indifferent to its presence
and are governed in their habitat by the physical conditions presented:
so in the case of saline lands the salts may attract or repel certain
plants. The latter class is much the largest; while there is also a
number of plants which are more or less indifferent to the presence
of salts, provided these be not in very great excess. Such plants
constitute the next-largest class; while those attracted by salts, and
whose welfare is conditioned upon their presence, are comparatively few
in number, and still fewer among them are of economic importance. Hence
the soluble salts have largely a negative importance for agriculture;
the question usually being how to utilize the land until the
undesirable surplus of salts can be got rid of, partially or wholly, as
the case may be; the former usually in seashore lands, the latter in
the alkali lands proper; in which a small remnant, not sufficient to
injure crop plants, is usually desirable (see chap. 23, p. 462).
_General Character of Saline Vegetation._—Those familiar with seashore
marshes cannot fail to note the fleshiness and succulence of the
characteristic plants. This “incrassation” belongs not only to the
saline flora proper, but is acquired to a greater or less degree when
plants not ordinarily at home on saline ground are transferred to it
artificially, or by saline overflows; while at the same time the leaves
usually become smaller, and the growth more compact. Correspondingly,
when saline plants are transferred to non-saline ground, the leaves
generally become thinner and larger, and the growth more slender. The
well-known “Russian thistle” is a case in point, as is also its close
relative, the soda saltwort (_Salsola soda_); although the latter does
not often venture as far from the saline lands as does the former
(_Salsola kali tragus_), which now seems to have become a world-wide
weed, with only a shade of preference for alkali lands.
_Structural and Functional Differences Caused by Saline Solutions._—It
has been definitely shown by the investigations of Schimper, Brick,
Hoffmann, Lesage, Rosenberg and others, that the peculiarities or
changes of structure brought about by saline solutions are essentially
those pertaining to xerophile (drought-enduring) vegetation; which in
general tend to the diminution of evaporation from the plant surfaces.
It may be said, roughly speaking, that the absorption of water by the
roots begins to diminish so soon as the concentration of the saline
solution approaches or exceeds one-half of one per cent; while when
it rises as high as three per cent, water-absorption by the roots
ceases even in the wettest soils, and the plant suffers from drought
quite as much as from any directly injurious effects of the salts.
Different plants of course differ in the measure of concentration which
brings about these phenomena, which vary also with the character of
the soluble salts. It is stated that injurious or useless salts like
common salt act at lower concentrations than _e. g._, saltpeter, which
is useful. The difference in external structure are: diminution of the
size of leaves, assumption of cylindrical or spinous forms, sinking-in
of the breathing pores below the outer surface, dense hairy covering,
resinous exudations, etc. Internally we find that xerophile plants have
developed on their upper or outer leaf-surfaces instead of one, several
layers of “palisade” (long and erect, closely-packed) cells, through
which transpiration is extremely slow, as is also the transmission
of heat. When salt-tolerant plants are grown on saline soils, their
palisade cells are relatively lengthened.
Coincident with these external means for the retardation of
evaporation, the leaves of xerophiles are frequently supplied
with special water-storage cells, which supply moisture for the
physiological processes when the root supply falls short. The cactus
tribe and similar-looking plants are examples of the latter provision,
which causes even animals suffering from thirst to resort to them,
although they eschew the saline vegetation.
_Absorption of the Salts._—The true halophytes or exclusive salt
plants, which refuse to grow on lands not containing a large
proportions of salt, often absorb so much salt that on drying it blooms
out on their surface; they usually have, even when green, a distinctly
salty taste, and their ash is rich in chlorids, specially of sodium.
Such is the case of the samphire, common in saline marshes everywhere.
The total ash is usually very high, often varying with the salinity of
the water or soil in which they have grown. Thus the salt-content of
the ash of samphire may vary by several per cent. In other cases, as in
that of one of the Australian saltbushes investigated at the California
station, neither the ash content nor the composition of the ash varies
materially whether the plant be grown on strong alkali land, or on
uplands whose total saline content does not exceed (in four feet depth)
.015% or 2500 pounds per acre.
The following table gives the composition of the ash of this saltbush
alongside of that of two other prominent alkali-plants of the same
relationship, occurring, one in the San Joaquin valley of California,
in strongly saline lands, the other in the Great Basin region of the
interior, on lands strongly impregnated with carbonate of soda. All
these, it will be seen, take up very large amounts of sodium salts,
notably the chlorid; the Australian plant most so, the “greasewood” of
the Great Basin least so; a large proportion of the alkali salts being
evidently, in the latter case, contained in the form of organic salts,
which in the ash become carbonates.
ANALYSES OF ASHES OF SALINE AND ALKALI PLANTS.
(A) = Australian Saltbush, Atriplex semibaccata.†
(B) = Bushy Samphire, Allenrolfea occidentalis.†
(C) = Greasewood, Sarcobatus vermiculatus.†
(D) = Saltgrass, Distichlis spicata.‡
(E) = Tussock grass, Sporobolus airodies.‡
(F) = Prickly Pear, Opuntia macrocentra.‡
========================+======+======+======+======+======+======
| (A) | (B) | (C) | (D) | (E) | (F)
------------------------+------+------+------+------+------+------
Ash, air-dried plant, %.| 19.37| 12.03| 13.81| 11.61| 7.99| 24.18
------------------------+------+------+------+------+------+------
Potash (K₂O) | 11.42| 18.53| 30.11| 3.30| 5.78| 1.61
Soda (Na₂O) | 35.39| 39.45| 32.58| 2.38| 5.15| 2.76
Lime (CaO) | 5.75| 1.36| 8.70| 5.25| 8.05| 65.66
Magnesia (MgO) | 3.23| 1.09| 1.09| 2.95| 4.15| 26.70
------------------------+------+------+------+------+------+------
Br. ox. of Manganese | | | | | |
(Mn₃O₄) | .22| | | .16| .25|
------------------------+------+------+------+------+------+------
Peroxid of Iron (Fe₂O₃) | 3.33| 7.06| not | 2.22| 2.39| 1.19
Alumina (Al₂O₃) | | |det’d.| | |
------------------------+------+------+------+------+------+------
Silica | 16.24| 11.81| 4.00| 78.73| 66.79| .81
Phosphoric acid (P₂O₅) | 2.80| 3.51| 5.60| .83| 1.25| .47
Sulfuric acid (SO₃) | 2.64| 4.93| 5.90| 3.20| 4.52| .64
Chlorin, percent | 24.33| 15.30| 11.00| 1.40| 2.13| .21
------------------------+------+------+------+------+------+------
Totals |105.35|103.04| 99.79|100.31|100.46|100.05
Less excess, O: Cl | 5.35| 3.25| 2.50| .31| .46| .05
------------------------+------+------+------+------+------+------
True totals |100.00| 99.79| 97.29|100.00|100.00|100.00
------------------------+------+------+------+------+------+------
(G) = Shad scale, Atriplex canescens.‡
(H) = Alfalfa Hay. (Cal.)†
(I) = Timothy Hay.
OF FORAGE CROPS.
============================+========+========+=======
| (G) | (H) | (I)
----------------------------+--------+--------+-------
Ash, air-dried plant, %. | 4.23 | 9.85 | 6.15
----------------------------+--------+-------+-------
Potash (K₂O) | 25.17 | 43.72 | 28.80
Soda (Na₂O) | 6.23 | 4.48 | 2.70
Lime (CaO) | 25.97 | 20.51 | 9.83
Magnesia (MgO) | 16.63 | 2.56 | 3.60
Br. ox. of Manganese (Mn₃O₄)| .51 | |
----------------------------+--------+--------+-------
Peroxid of Iron (Fe₂O₃) | 5.89 | 2.95 |
Alumina (Al₂O₃) | | |
----------------------------+--------+--------+-------
Silica | 11.94 | 5.87 | 35.00
Phosphoric acid (P₂O₅) | 3.11 | 5.00 | 10.80
Sulfuric acid (SO₃) | 4.93 | 6.92 | 3.90
Chlorin, percent | 2.07 | 10.25 | 5.00
----------------------------+--------+--------+-------
Totals | 100.45 | 102.26 | 99.70
Less excess, O: Cl | .45 | 22.6 | 1.13
----------------------------+--------+--------+-------
True totals | 100.00 | 100.00 | 98.57
----------------------------+--------+--------+-------
† Jaffa, Cal. St’n. Rept. 1894-95, p. 169.
‡ Goss, New Mex. St’n. Bull. No. 44; recalculated.
It will be noted that the saltbush hay contains nearly one-fifth of
its (air-dry) weight of ash, of which nearly 40% is common salt. It
therefore has a distinctly salty taste, and is always moist to the
touch, containing-ordinarily over 15% of moisture. It is therefore much
liked by stock when fed intermixed with other hay, and thus supplies
all the salt needed by cattle. The greasewood is much less liked by
stock, and bushy samphire is wholly rejected by them. Comparing with
these fleshy plants the ash of the two grasses, the first a world-wide
“salt grass,” the other a common grass of the American arid region,
we note that not only do they contain much less soluble ash than the
saltbushes, but especially much smaller amounts of sodium salts;
proving that even when growing in company with the saltbushes on
strongly impregnated land, they can repel from absorption these to them
useless or injurious salts. But in the case of the “shad scale,” also a
“saltbush” of the Great Basin, the ash-content is remarkably low—only
about one-fifth of that of its Australian relative—and it differs
widely from the latter in having but a very low proportion of soda,
and a very high one of lime and potash, approaching in these respects
to our usual forage crops; and being also fairly rich in nitrogen, it
forms acceptable browsing when other pasture plants are scarce. It
therefore does not exert the laxative action produced by the exclusive
feeding on the more saline herbages.
The exceptionally high ash-content of the cactus or prickly pear, also
given in the table, arises, it will be noted, not from the soluble
salts but from the absorption of extraordinarily high proportions of
lime and magnesia. Owing probably to the latter substance, and also the
oxalate form in which lime is usually found in the cactus tribe, this
plant when used as forage is also somewhat laxative.
Altogether, this table offers remarkable examples of wide differences
in the kind and amount of ash ingredients absorbed by plants growing
upon similar soils and under identical climatic conditions; indicating
a selective power which no merely physical theory of soil-action in
plant growth can explain.
_Injury to Plants from the Various Salts._—The early observers,
especially Contejean, were predisposed from their observations of lime
on vegetation to ascribe the action of salt upon marine vegetation
to the sodium component. But the wide differences in the effects of
different sodium compounds, notably of common salt and Glaubers salt,
led some to the conclusion that the acidic ingredients are the chief
determining factors. Moreover, it was soon found that a single salt is
more injurious than a mixture of several, such as sea water. This also
led to the inference that the varying degree of dissociation of these
salts essentially influences the effects.
Kearney and Cameron have investigated these relations,[201]
and have by artificial cultures in solutions of varying
concentration and composition studied the behavior of plant
roots and the limits of their endurance. They found for the
several salts occurring in alkali soils, taken separately,
the following figures, in 100,000 parts of water:
Magnesium sulfate 7
“ chlorid 12
Sodium carbonate 26
“ sulfate 53
“ chlorid 116
“ bicarbonate 167
Calcium chlorid 1,377
[201] Report No. 71, U. S. Dep’t. of Agriculture, 1902.
It will be noted that in many respects the results given in
this table stand in marked contrast to the facts observed
in alkali lands everywhere; and therefore while interesting
physiologically, are not directly applicable to practice.
Magnesium sulfate, which according to this table is the most
injurious of all, is a common ingredient of alkali lands
from Wyoming to New Mexico, as also is sodium sulfate; yet
there, as well as in the Musselshell valley in Montana, and
at many other points, it shows no specially deleterious
action either upon native or cultivated plants, and in
Europe as well as in New England the mineral kieserite is
freely used as a fertilizer at many points. That sodium
sulfate should be twice as harmful as sodium chlorid or
common salt, and half as harmful as the carbonate or black
alkali, is again wholly contrary to actual experience,
which as shown elsewhere in this chapter, indicates that
the majority of plants will tolerate between three and four
times as much of sodium sulfate as of common salt; while the
ratio of tolerance as against the carbonate seems sometimes
to rise as high as ten to one.
It is clearly evident, however, that it is the metallic or
basic ingredient that in the main determines the toxicity of
these salts. The universal presence of lime in some form in
all alkali lands doubtless explains the discrepancies
mentioned, since lime is especially potent in counteracting
the injurious effects; thus throwing additional light upon
the importance of the lime-content of alkali soils proper,
and also upon the causes of the narrow limitations of
the littoral (marine saline) flora; inasmuch as, unlike
alkali soils, marine alluvial lands are by no means
always calcareous. Cameron goes so far as to attribute
the favorable effects of gypsum upon black alkali not so
much to the conversion of the latter into neutral sulfate,
as to the effect of gypsum solution in counteracting the
saline effects. This interpretation, however, seems rather
far-fetched, since there can be no question about the double
decomposition of gypsum with carbonate of soda; or the
intense injuriousness of carbonate of soda in the actual
corrosion of vegetable tissues. The corresponding protective
influence of various salts, more especially of those of
lime, against the injurious effects of pure common salt on
marine animals, has already been mentioned (chapter 20, page
380), and later investigations by Osterhout on marine algæ,
show the same relation to hold true for them also.
_Reclamation of Marine Saline Lands for Culture._—The reclamation of
sea-coast lands and marshes for agricultural use is based in general
upon the same methods as those already outlined for alkali lands in
chapter 20; except that in this case no chemical neutralization is
possible, since common salt cannot be changed by any practically
feasible means. It must be removed by leaching, and this, in the humid
countries in which such reclamations have chiefly been made, is usually
done by the agency of rains, aided by ditching. The “polder” lands thus
reclaimed along the shores of the North Sea, from Belgium to Prussia,
are especially esteemed for their productiveness, doubtless owing to
the alluvium of the numerous rivers tributary to that sea, which is
distributed along its shores and in the numerous inlets and bays. The
tides are of course excluded by dikes provided with gates opening
outward, so as to permit of the outflow of rain- or irrigation-water
used for leaching purposes.
Out of reach of stream alluvium no exceptional fertility is to be
expected of seashore lands, which then commonly assume the form of sand
dunes or bars, incapable of nourishing any cultural vegetation. Of the
latter, the groups listed below as tolerant of alkali salts, may also
be considered with reference to reclaimed seashore lands; the first
cereal to succeed being usually barley, the first root crop, beets.
Asparagus is also available while salt is being leached out.
THE VEGETATION OF ALKALI LANDS.
The general character of alkali-land vegetation is not unlike that of
saline seashore lands; some species of plants are common to both, but
the alkali lands harbor a much greater variety of plants, owing to
the differences in climates and soils as well as to the nature of the
impregnating salts. Moreover, owing to the very causes which underlie
the presence of these salts, viz, aridity, the xerophile or dry-land
character of the alkali-land flora is much more pronounced than that of
the saline seashore vegetation. In view of the very complex conditions,
the discussion of the alkali-flora is of necessity much more complex
than that of the marine group; and the data for its full elucidation
with respect to the nature of the soils and salts are as yet very
incomplete.
RECLAIMABLE AND IRRECLAIMABLE ALKALI LANDS AS DISTINGUISHED BY THEIR
NATURAL VEGETATION.
While, as shown above (chapter 20), the adaptation or non-adaptation
of particular alkali lands to certain cultures may be determined by
sampling the soil and subjecting the leachings to chemical analysis, it
is obviously desirable that some other means, if possible available to
the farmer himself, should be found to determine the reclaimability and
adaptation of such lands for general or special cultures.
In alkali lands, as in others, the natural plant-growth affords
such means, both as regards the quality and quantity of the saline
ingredients. The most superficial observation shows that certain plants
indicate extremely strong alkali lands where they occupy the ground
alone; others indicate pre-eminently the presence of common salt;
the presence or absence of still others form definite or probable
indications of reclaimability or non-reclaimability. Many such
characteristic plants are well known to and readily recognized by the
farmers of the alkali districts. “Alkali weeds” are commonly spoken
of almost everywhere; but the meaning of this term—_i. e._, the kind
of plant designated thereby—varies materially from place to place,
according to climate as well as the quality of the soil. It is obvious
that if these characteristic plants were definitely observed, described
and named, while also ascertaining the amount and kind of alkali they
indicate as existing in the land, lists could be formed for the several
regions, which would indicate, in a manner intelligible to the farmer
himself, the kind and degree of impregnation with which he would have
to deal in the reclamation work; thus enabling him to go to work on the
basis of his own judgment, without previous chemical examination.
A study of the lands of California having this purpose in view, was
undertaken in the years 1898 and 1899 by the California Station; but
lack of funds prevented its prosecution beyond the ascertainment
of those plants the abundant occurrence of which prove the land
to be irreclaimable without the use of the universal remedy, viz,
underdrainage, which on the large scale is usually beyond the means
of the land-seeker. The botanical field work and collection of soil
samples was carried out by Mr. Jos. Burtt Davy; the chemical work,
as heretofore, being done by Dr. R. H. Loughridge. The results here
reported are therefore essentially their joint work. It is hoped that
in the future, a more comprehensive study and close comparison of
the native vegetation with the chemical determination of the quality
and kind of alkali corresponding to certain plants, or groups of
plants, naturally occurring on the land, may enable us to come to a
sufficiently close estimate of the nature and capabilities of the
latter from the native vegetation alone, or with the aid of test plants
purposely grown, for the farmers’ purposes.
_Plants Indicating Irreclaimable Lands._—The plants herein-after
mentioned and figured are, then, to be understood as indicating,
_whenever they occupy the ground as an abundant and luxuriant growth_,
that such land is irreclaimable for ordinary crops, unless underdrained
for the purpose of washing out surplus salts. The occurrence merely of
scattered, more or less stunted individuals of these plants, while a
sure indication of the _presence_ of alkali salts, does not necessarily
show that the land is irreclaimable.
The plants which may best serve as such indicators in California are
the following:
Tussock-grass (_Sporobolus airoides_ Torr.), Fig. 82.
Bushy Samphire (_Allenrolfea occidentalis_ [Wats.] Ktze.),
Fig. 83.
Dwarf Samphire (_Salicornia subterminalis_ Parish, and
other species), Fig. 84.
Saltwort (_Suaeda torreyana_ Wats., and _S. suffrutescens_,
Wats.), Fig. 85.
Greasewood (_Sarcobatus vermiculatus_ [Hook.] Torr.),
Fig. 86.
Alkali-heath (_Frankenia grandifolia campestris_ Gray),
Fig. 87.
Cressa (_Cressa truxillensis_ Choisy), Fig. 88, perhaps
identical with _C. cretica_ auct.
Saltgrass (_Distichlis spicata_), Fig. 89.
TUSSOCK-GRASS (_Sporobolus airoides_, Torr.); Fig. 82.
(“Bunch grass” of New Mexico).
The three sets of Tussock-grass soil which have been analyzed show
that the total amount of all salts present is in no case less than
49,000 pounds per acre, to a depth of four feet; and that it sometimes
reaches the extraordinarily high figure of 499,000 pounds. Of these
amounts the neutral salts (Glauber’s salt and common salt) are usually
in the heaviest proportion (Glauber’s salt, 19,600 to 323,000 pounds
per acre; common salt, 3,500 to 172,800); the corrosive salsoda varying
from 3,000 to 44,000 pounds.—Tussock-grass apparently cannot persist
in ground which is periodically flooded. It is of special importance
because it is an acceptable forage for stock.
Tussock-grass is a prevalent alkali-indicator in the hot, arid portions
of the interior, from the upper San Joaquin Valley, the Mojave desert,
and southward; also through southern Nevada and Utah as far east as
Kansas and Nebraska. In the San Joaquin Valley it has not been found
farther north than the Tulare plains, although east of Reno it occurs
near Reno. Coville observes that in the Death Valley region “it is
confined principally to altitudes below 1,000 meters” (3,280 feet).
Hillman, however, reports it from near Reno, Nevada, at an altitude
which cannot be much less than 4,500 feet.
[Illustration: FIG. 82.—Tussock-Grass—_Sporobolus airoides_ Torr.]
The tussocks formed by this grass, which are unfortunately not shown in
the figure, sometimes appear as veritable little grass trees, and when
denuded by the browsing of cattle seem like trunks 18 and 20 inches
high. It is therefore very easily recognized; but it should be noted
that in view of the extraordinary range of its tolerance, shown above,
its scattered occurrence does not necessarily indicate irreclaimable
land.
BUSHY SAMPHIRE. (_Allenrolfea occidentalis_ [Wats.] G. Ktze.) FIG. 83..
This plant is locally called greasewood, but as this name is much more
commonly used for _Sarcobatus vermiculatus_, it seems best to call
Allenrolfea “bushy samphire,” as it closely resembles the true samphire
(_Salicornia_).
Bushy Samphire usually grows in low sinks, in clay soil which in
winter is excessively wet, and in summer becomes a “dry bog.” Wherever
the plant grows luxuriantly the salt content is invariably high, the
total salts varying from 327,000 pounds per acre, to a depth of three
feet, to 494,520 pounds in four feet. The salts consist mainly of
Glauber’s and common salts (a maximum of about 275,000 pounds each);
salsoda varies from 2,360 to 4,800 pounds per acre. The percentage
of common salt and total salts is higher than for any other plant
investigated, and the content of Glauber’s salt is also excessive.
The areas over which this plant grows must therefore be considered
among the most hopeless of alkali lands, for although its salts are
“white,” submergence during winter precludes the growth of Australian
saltbushes. Full underdrainage alone could reclaim the soil-areas it
occupies. Bushy Samphire is common on low-lying alkali lands in the
upper San Joaquin Valley, California, and extends northward along the
eastern slopes of the Coast Range to Suisun Bay. It is also abundant in
the Death Valley region, apparently overlapping the southward range of
the _Sarcobatus_, the greasewood properly so-called.
DWARF SAMPHIRE (_Salicornia subterminalis_, Parish, and other species
of the interior); Fig. 84.
[Illustration: FIG. 83.—Bushy Samphire—_Allenrolfea occidentalis_ (S.
Wats.) G. Ktze.]
[Illustration: FIG. 84.—Salicornia subterminalis. Alkali samphire.
A. Much-branched form.
B. Slender form.
C. Flower with the perianth removed showing the simple pistil and the
two stamens.
D. Portion of flowering spike, showing two joints. The flowers are
impressed in the joints in opposite clusters of three. In each cluster
the middle flower stands slightly above the two laterals as shown in
the lower joint.]
The three or four species of Dwarf Samphire which grow in the interior
valleys of the State are not usually very abundant, save locally.
Wherever the species do occur, however, they may be considered as
indicating excessively saline soils. Dwarf Samphire soil has shown
a total salt content of 441,880 pounds per acre in a depth of four
feet. The neutral Glauber’s salt amounts to 314,000 pounds, almost
as much as in Tussock-grass soil; common salt up to 125,640 pounds
while the salsoda varies from 2,200 to 12,000. We may consider the
plant as indicative of almost the highest percentage of common salt,
Glauber’s salt and total salts. Like the preceding species it indicates
land strongly charged with salts, more especially common salt, and
susceptible to cultivation only after reclamation by underdrainage.
_Salicornia subterminalis_, _S. herbacea_ (L.), _S. mucronata_, and
another species, all occurring inland, differ materially in habit and
botanical characters from the one so conspicuous in submerged salt
marshes along the seashore; but all alike indicate strongly saline
soils, reclaimable only by thorough drainage.
SALTWORT (_Suaeda torreyana_, Wats., _S. suffrutescens_, Wats., and
perhaps one other species); Fig. 85.
Samples of saltwort soil from Bakersfield and Byron Springs,
California, taken to a depth of one foot and three feet respectively,
show that this plant grows luxuriantly in a soil containing 130,000
pounds of total salts per acre in the first foot, and with 10,480
pounds of the noxious salsoda, and 39,760 pounds of common salt in
three feet; while only a sparse growth is found on soils containing
only 3,700 pounds of salts in three feet. It thus appears to indicate
a lower percentage of salsoda than does Greasewood, but a higher
percentage than Bushy Samphire. Further investigation is necessary
to determine the exact relation of the different salts to the growth
of the plant, and as to whether carbonates occur in large quantity;
but enough data have been gathered to show that a luxuriant growth of
Suaeda torreyana indicates a soil reclaimable only by thorough-drainage.
Suaeda torreyana occurs on low alkali lands throughout the State of
California, from San Bernardino to Honey Lake, in the desert sinks,
and in the Great Valley, in appropriate locations. Sometimes it is
replaced by _S. suffrutescens_ and perhaps other species, but all the
saltworts appear to grow in similar habitats, and it is probable that
the soil-conditions are practically the same for all these species.
They indicate land too heavily impregnated for the growth of ordinary
crops, but which will perhaps allow the Australian saltbush to succeed.
[Illustration: FIG. 85.—Saltwort—_Suaeda Torreyana_, Wats.]
GREASEWOOD (_Sarcobatus vermiculatus_) [Hook. Torr.]; FIG. 86.
This, the true _Greasewood_ of the desert region east of the Sierra
Nevada, and not either of the plants known under that name in the San
Joaquin Valley and in Southern California, invariably indicates a
heavy impregnation of the land with black alkali or carbonate of soda.
Since, as before stated, black alkali is most likely to occur in low
ground, we frequently find the true greasewood forming bright green
patches in the swales, and on the benches of periodic streams, as well
as on the borders of alkali ponds or lakes. Stock unaccustomed to it
will frequently go to these patches on a run, only to turn away badly
disappointed after taking a few bites, the plant being both bitter and
salty.
[Illustration: FIG. 86.—Greasewood (proper)—_Sarcobatus vermiculatus_
(Hook) Torr.]
A. Appearance of a branch when not in blossom.
B. Spiny-branchlet from the same.
C. Branchlet bearing cones of male flowers.
D. Cone of male flowers, enlarged.
E. Branch bearing fruits.
F. Cluster of fruits, enlarged.
G. Vertical section through a fruit, showing the seed with its
curved embryo, (enlarged).
Where a luxuriant growth of this plant is found, the soil may contain
from 38,000 to 117,000 pounds of total salts per acre, of which
sometimes nearly half is carbonate of soda; the content of common salt
is usually low, and Glauber’s salt or sulfate of soda, sometimes with
considerable proportion of epsom salt, forms a variable proportion of
the total.
Greasewood is distinctly a plant of the Great Basin, only reaching
California in the adjacent counties of Lassen, Alpine, Mono, and
northern Inyo. It is very abundant on the lower levels of Honey Lake
valley, Cal.
The Sarcobatus is chiefly found on silty or sandy soils of good
native fertility (see page 445, chapter 22), so that when its excess
of salsoda is neutralized by means of gypsum, the land becomes very
productive. Unfortunately the cost of the amount of gypsum required
to render such soils adapted to the tolerance of most culture plants
is often prohibitive; but where the correction of only small spots is
called for, the “white alkali” resulting from the gypsum treatment
would be tolerated by many culture plants.
ALKALI-HEATH (_Frankenia grandifolia campestris_ Gray); Fig. 87.
[Illustration: FIG. 87.—Alkali-Heath—_Frankenia grandifolia campestris_
A. Gray.]
Alkali-heath is perhaps the most widely distributed of any of the
California alkali plants. Its perennial, deep-rooting habit of growth,
and flexible, somewhat wiry rootstock, which enables it to persist
even in cultivated ground, render it a valuable plant as an alkali
indicator. The salt-content where Alkali-heath grows luxuriantly is
invariably high, ranging from 64,000 to 282,000 pounds per acre;
salsoda varies from 680 to 19,590 pounds; common salt ranges from 5,000
to 10,000 pounds. Such soils would not be benefited by the application
of gypsum, as the salts are already largely in the neutral state. Of
useful plants only Saltbushes and Tussock-grass are likely to flourish
in such lands, when not too wet.
While Alkali-heath is thus one of the most alkali-tolerant plants, it
is at the same time capable of growth with a minimum of salts (total
salts 3,700 pounds, salsoda 680 pounds). Where only a sparse growth of
this plant occurs, therefore, the land should not be condemned until a
chemical examination of the soil has been made.
Alkali-heath is found on soils of very varying physical texture
and degrees of moisture; while on soils of uniform texture and
moisture-conditions, but differing in chemical composition, it varies
with the varying salt-content.
It has been found that Australian saltbush (_Atriplex semibaccata_) can
be successfully grown on the “goose-lands,” of the Sacramento Valley,
on soil producing a medium crop of Alkali-heath; it remains to be
shown whether it will do equally well on soils producing a dense and
luxuriant growth of the same.
Alkali-heath is widely distributed throughout the interior valleys of
California; a closely related form grows in the salt-marshes of the
sea-coast.
CRESSA (_Cressa cretica truxillensis_ Choisy); Fig. 88.
Cressa soils show a low percentage of the noxious salsoda, but
comparatively heavy total salts (161,000 to 282,000 pounds per acre.)
Common salt varies from 5,760 to 20,840 pounds per acre in four feet.
The maximum is lower than in the case of Alkali-heath, but Cressa
seems to be much more closely restricted to strong alkali than does
the former species. Cressa appears to be as widely distributed through
the interior valleys of California as Alkali-heath. The Cressa is a
cosmopolitan plant, occurring, as its name indicates, on the Ionian
Islands, as well as in North Africa, Syria, and other arid countries of
the world.
SALTGRASS, _Distichlis spicata_.—This grass is of world-wide
distribution, and always indicates a sensible content of soluble salts,
without apparently any special preference for either of the three most
commonly occurring ones. Its maximum tolerance, as will be seen by
the preceding table, is very high, yet at the same time it will grow
luxuriantly on lands containing so little that other saline plants
like the samphires, saltwort or greasewood will refuse to grow. On
the shores of Honey Lake, California, it may often be seen incrusted
with the salts of the water concentrated by a long season of drought,
yet maintaining life, though somewhat stunted. On lands lightly
impregnated, stock will often eat it quite freely, so that it has been
mistaken for Bermuda grass, to which its habit and foliage bears some
resemblance. But Bermuda grass, while not as sensitive to alkali as
most forage grasses, will probably not bear much over 12,000 pounds per
acre.
[Illustration: FIG. 88.—Cressa—_Cressa cretica truxillensis_, Choisy.]
The mere _presence_ of the salt grass cannot therefore be taken as a
definite indication of anything more than that there is an unusual
amount of salts in the soil; whether or not there is more than will be
tolerated by the ordinary culture-plants, must be judged either from
the accompanying plants, or by experiment or analysis.
[Illustration: FIG. 89.—Salt-Grass—_Distichlis spicata_ (L.) Greede.]
_Relative Tolerance of the Different Species._—The following table
shows in systematic order the tolerance of the several plants discussed
above, for the different salts, so far as the data available permit.
The column marked _optimum_ shows under what proportions of salts the
plants grew in about equal luxuriance, therefore under, apparently,
the most favorable conditions. Both above and below the proportions
mentioned in that column, the luxuriance (size) and (usually) the
abundance of the plants was less; showing that while excessive amounts
of salts depressed their welfare, yet they also suffered when the
proportions dropped below a certain point. Whether this was partly or
wholly the result of competition with other plants, is an unsettled
question.
TABLE SHOWING MAXIMUM, OPTIMUM, AND MINIMUM OF SALTS
TOLERATED BY EACH OF THE SEVERAL ALKALI PLANTS.
-------------------------------+-----------------------------
| Pounds Per Acre in feet.
+-----------+--------+--------
| Optimum. |Maximum.|Minimum.
-------------------------------+-----------+--------+--------
_Total Salts._ | | |
Bushy Samphire | 494,320 | 494,520| 135,060
Dwarf Samphires | 441,880 | 441,880| 441,880
Alkali-heath |{ 281,960}| 499,040| 3,720
|{ 64,300}| |
Cressa | 281,960 | 281,960| 161,160
Saltworts | 130,000 | 153,020| 3,720
Greasewood | 58,560 | 58,560| 2,400
Tussock-grass | 49,000 | 499,040| 49,000
| | |
_Carbonate_ (Salsoda). | | |
Tussock-grass | 23,000 | 44,460| 3,040
Alkali-heath [202]| { 19,590}| 19,590| 680
| { 680}| |
Greasewood | 18,720 | 18,720| 1,280
Dwarf Samphires | 12,120 | 12,120| 2,200
Saltworts | 10,480 | 12,120| 1,120
Cressa | 5,440 | 5,440| 680
Bushy Samphire | 4,800 | 4,800| 1,500
| | |
_Chloride_ (Common Salt). | | |
Bushy Samphire | 212,080 | 275,160| 56,800
Dwarf Samphires | 125,640 | 125,640| 125,640
Saltworts | 39,760 | 52,900| 1,040
Cressa | 20,840 | 20,840| 5,760
Alkali-heath |{ 10,180}| 212,080| 1,040
|{ 5,760}| |
Tussock-grass | 6,200 | 172,800| 3,530
Greasewood | 3,680 | 3,680| 160
| | |
_Sulphates_ (Glauber’s salt). | | |
Dwarf Samphires | 314,040 | 314,040| 314,040
Bushy Samphire | 277,640 | 277,640| 50,080
Cressa | 275,520 | 275,520| 134,880
Alkali-heath |{ 275,520}| 323,200| 1,560
|{ 34,530}| |
Saltworts | 44,160 | 104,040| 1,560
Greasewood | 36,160 | 36,160| 960
Tussock Grass | 19,640 | 323,200| 19,640
-------------------------------+-----------+--------+--------
[202] This plant grows with equal luxuriance in soils containing only
680 pounds of carbonates.
APPENDICES.
APPENDIX A.
DIRECTIONS FOR TAKING SOIL SAMPLES. ISSUED BY THE CALIFORNIA EXPERIMENT
STATION.
In taking soil specimens for examination by the Agricultural Experiment
Station, the following directions should be carefully observed; always
bearing in mind that the examination, and especially the analysis, of
a soil is a long and tedious operation, which cannot be indefinitely
repeated.
_First._—Do not take samples at random from any points on the land, but
consider what are the two or three chief varieties of soil which, _with
their intermixtures_, make up the cultivable area, and carefully sample
these, each separately; then, if necessary, sample your particular
soil, noting its relation to these typical ones.
_Second._—As a rule, and whenever possible, take specimens from spots
that have not been cultivated, nor are otherwise likely to have been
changed from their original condition of “virgin soils”—_e.g._, not
from ground frequently trodden over, such as roadsides, cattle-paths,
or small pastures, squirrel holes, stumps, or even the foot of trees,
or spots that have been washed by rains or streams, so as to have
experienced a notable change, and not be a fair representative of their
kind.
_Third._—Observe and record carefully the normal vegetation, trees,
herbs, grass, etc., of the average virgin land; avoid spots showing
unusual growth, whether in kind or in quality, as such are likely to
have received some animal manure, or other outside addition.
_Fourth._—Always take specimens from more than one spot judged to
be a fair representative of the soil intended to be examined, as an
additional guarantee of a fair average, and mix thoroughly the earth
_taken from the same depths_.
_Fifth._—After selecting a proper spot, pull up the plants growing
on it, and sweep off the surface with a broom or brush to remove
half-decayed vegetable matter not forming part of the soil as yet. Dig
or bore a vertical hole, like a post-hole, and note at what depth a
change of tint occurs. In the humid region, or in humid lowlands of
the arid, this will usually happen at from six to nine inches from the
surface, and a sample taken _to_ that depth will constitute the “soil.”
In California and the arid region generally, very commonly no change
of tint occurs within the first foot, sometimes not for several feet;
hence, especially in sandy lands, the “soil” sample will usually be
taken to that depth, so as to represent the _average of the first foot_
from the surface down.
_Samples taken merely from the surface, or from the bottom of a hole,
have no definite meaning, and will not be examined or reported upon._
Place the “soil” sample upon a cloth (jute bagging should not be used
for the purpose, as its fibres, dust, etc., become intermixed with the
soil) or paper, break it up, mix thoroughly, and put _at least a quart_
of it in a sack or package properly labeled, for examination.
This specimen will, ordinarily, constitute the “soil.” Should the
change of color occur at a less depth than six inches, the fact should
be noted, but the specimen taken to that depth nevertheless, since it
is the least to which rational culture can be supposed to reach.
In the same way take a sample of each foot separately to a depth of at
least three feet; preferably four or five, especially in the case of
alkali soils, or suspected hardpan.
_Sixth._—Whatever lies beneath the line of change, or below the minimum
depth of six inches, will constitute the “subsoil.” But should the
change of color occur at a greater depth than twelve inches, the “soil”
specimen should nevertheless be taken to the depth of twelve inches
only, which is the limit of ordinary tillage; then another specimen
from that depth down to the line of change, and then the “subsoil”
specimens beneath that line.
The depth down to which the last should be taken will depend on
circumstances. It is always necessary to know what constitutes the
foundation of a soil, down to the depth of three feet _at least_, since
the question of drainage, resistance to drought, root-penetration,
etc., will depend essentially upon the nature of the substratum. In
the arid region, where roots frequently penetrate to depths of ten
or twelve feet or even more, it is frequently necessary to at least
_probe_ the land to that depth or deeper. The specimens should be taken
in other respects precisely like that of the surface soil, _each to
represent the average of not more than twelve inches_. Those of the
materials lying below the third foot from the surface may sometimes be
taken at some ditch or other easily accessible point, and if possible
should not be broken up like the other specimens.
If there is _hardpan or heavy clay_ present, an unbroken lump of it
should be sent, for much depends on its character.
_Seventh._—When in the case of cultivated lands, it is desired to
ascertain the cause of differences in the behavior or success of a
crop on different portions of the same field or soil area, do not send
only the soil which bears unsatisfactory growth, but also the one
bearing normal, good growth, for comparison. In all such cases, try to
ascertain by your own observations whether or not the fault is simply
in the subsoil or substrata; in which case a sample of surface soil
sent for examination would be of little use. In such examinations the
soil probe will be of great service, and save much digging or boring.
_Eighth._—Specimens of alkali or salty soils should preferably be taken
towards the end of the dry season, when the surface layers will contain
the largest amount of salts. A special sample of the first six inches
should in that case be taken separately by means of a post-hole auger,
and then, in a different spot close by, a hole four feet deep should
be bored, and _the earth from the entire four-foot column_ intimately
mixed before the usual quart sample is taken. Samples of the plants
growing on the land should in all cases be included in the package, as
they indicate very closely the agricultural character of the land.
_All samples taken while the land is wet should be air-dried before
sending; in the case of alkali soils this is absolutely essential._
_Ninth._—All peculiarities of the soil and subsoil, their behavior
under tillage and cultivation in various crops, in wet and dry seasons,
their location, position, “lay,” every circumstance, in fact, that
can throw any light on their agricultural qualities or peculiarities,
should be carefully noted, and _the notes sent by mail_. _Without
such notes, specimens cannot ordinarily be considered as justifying
the amount of labor involved in their examination._ Any fault found
with the behavior of the land in cultivation or crop-bearing should
be specially mentioned and described. The conditions governing
crop-production are so complex that even with the fullest information
and the most careful work, cases are found in which as yet the best
experts will be at fault.
APPENDIX B.
SUMMARY DIRECTIONS FOR SOIL—EXAMINATION IN THE FIELD OR ON THE FARM.
While the general principles upon which the cultural value and
adaptations of lands should be judged, have been given in the text
of this volume, it seems advisable to summarize their practical
application to land examination here, for convenient reference.
The directions given in Appendix A for the sampling of soils having
been carried out, the samples so taken may be subjected to farther
examination by any intelligent farmer to good purpose, and often with
great saving of time and expense.
Spread the samples from the several depths in regular order upon a
table or bench, and note the differences in color and texture apparent
to the eye or touch, and whether they will or will not crush readily
between the fingers, wet and dry. Whatever the fingers can do, can
similarly be done by the harrow, cultivator, clod crusher or roller.
The tilling qualities of the surface soil and immediate subsoil are the
first and most important matter to be ascertained; including especially
their behavior to water. Place some air-dried lumps in a shallow dish
with a little water; observe whether they take up the water quickly
or slowly, and whether in so doing the lumps fall to pieces or retain
their form. Slow penetration, and maintenance of form, will at once
indicate a soil somewhat refractory and difficult to till; while if
the water is taken up easily and the lump falls to pieces, the land
is easily cultivated and will absorb the rainfall and irrigation
water readily. The darkening of the tint on wetting will also give an
approximate idea of its humus-content.
Then take a wetted lump and work it between the fingers and on the palm
of the hand, until its “stickiness” or adhesiveness ceases to increase.
This “hand test” is of first importance and in skillful hands will
largely supersede the need of elaborate mechanical analysis. It will
at once enable the operator to classify the soil as a light or heavy
loam, clay loam or clay soil; it will show directly what will be the
result of plowing the land when wet, the liability to the formation of
a plowsole, and whether a single or a double team will generally be
needed to cultivate it properly. Also whether stock can be allowed to
pasture the land soon after rain. Comparison with the known land of
neighbors will also thus become easy, and in a measure the crops best
adapted to the physical qualities of the soil, subsoil and substrata,
taking into account their respective depths, will at once be at least
approximately determined. The presence of coarse and fine sand in
greater or less amounts will also be thus readily ascertained, allowing
estimates of the percolative properties; the latter can, of course,
be more practically tested in the field, in the manner described in
chapter 13, page 242.
A more definite estimate of the amount and kind of sand present in the
soil materials can be obtained by washing the _kneaded_ sample into
a tumbler, and allowing a thin stream of water to flow into it from
a faucet while gently stirring the turbid water. The clay, together
with the finest silts, will thus be carried off over the rim of the
glass, and sand of any desired degree of fineness, according to the
strength of the stream of water used, will be left behind. The kind and
amount of these sandy materials can then be estimated, or definitely
ascertained by weighing or measuring.
This will, generally speaking, be as far as the uninstructed farmer
can readily go; but these simple operations will give him an insight
into the nature of his soil and subsoil that will enable him to avoid a
great many costly mistakes.
RECOGNITION AND MEANING OF THE SEVERAL SOIL MINERALS.[203]
Those somewhat familiar with scientific methods and operations, and
supplied with pocket lens or microscope, can profitably go much
farther towards the definite ascertainment of the permanent cultural
value of the land, by the study of the minerals of which the sand is
composed, and which as a rule represent those from which the entire
soil has been formed; therefore indicate in a general manner its
chemical composition. Such examinations are specially feasible and
important when soils are not far removed from their parent rocks, as
in most of the arid region, and in the states north of the Ohio. In
the Southwestern states, in the coastal plain of the Gulf of Mexico,
the original soil minerals have usually been too far decomposed to
admit of definite identification. Sand is there as a rule made up of
quartz grains of many varieties, with only an occasional tourmaline and
pyroxene.
[203] For more details see chapters 3 and 4.
Among the prominent soil minerals, quartz is almost always recognizable
by its glassy luster and the irregular fracture—absence of definite
planes or facets of cleavage, causing the grains to be abraded or
rounded nearly alike in all directions. The _feldspars_, on the
contrary, always show a tendency to cleave into fragments having
definite, obviously oblique angles, which are perceptible even when
the grains are somewhat worn; because of the difference in the ease
with which wear takes place in the several directions. _Potash
feldspar_, moreover, which is the most important to be recognized
because it indicates a relatively large supply of potash in the
natural soil, is but rarely glassy in luster, but mostly dull white,
or reddish-white.—The _lime_ and _lime-soda_ feldspars rarely show as
definite forms, because of their tendency to form complex crystalline
aggregates (twins): and their definite recognition requires somewhat
complex (polarizing) appliances in connection with the microscope. In
such cases, however, the accompanying minerals (hornblende, pyroxene,
mica and others) often afford valuable indications, because of their
known association with soda-lime feldspars in certain rocks.
An abundant occurrence of _hornblende_ fragments, characterized by
their flat, tabular form, and bottle-green or black tint, indicate,
almost always a fairly good supply of lime in the soil, but leaves
the potash-supply in doubt. _Pyroxene_ (distinguished by its smooth,
polished surface from the angularly-weathering, usually rusty
hornblende fragments) rarely occurs with potash feldspar; and soils
strongly charged with it are mostly poor in potash.
_Mica_ occurs in so many rocks and is of so little consequence as
a soil-ingredient from the chemical point of view, because of its
difficult decomposition, that its presence can mostly only serve to
corroborate or contradict conclusions as to the derivation of a soil
from some particular rock or region. But mica serves a good purpose in
improving the tilling qualities of soils. Its thin scales must not be
mistaken for the tabular fragments of hornblende.
_Calcite_ in its several forms is mostly easily recognized both by
its form under the microscope, and by the effervescence its granules
show when touched with an acid. This effervescence can generally be
observed on touching the wetted soil with chlorhydric acid, so soon as
the content exceeds two per cent; but something depends upon the size
of the grains, as when these are very small, the giving-off of gas is
less readily noted. To facilitate it, the wetted soil may be warmed
before touching it with the acid. The recognition of the presence of
lime carbonate in soils is so important as to justify considerable
trouble in rendering it definite. When the aid of a chemist cannot be
commanded, fairly definite conclusions may be drawn from the character
of the native vegetation; regarding which, detailed information may
be found in Parts III and IV of this volume. But where, as in the
arid region, this criterion is not available, since the controlling
factor there is the moisture supply, a presumption may be gained by the
application of a slip of moistened red litmus paper to the _wetted_
soil. Should the red paper be turned blue within one or two minutes
it would indicate the presence of carbonate of soda (“black alkali”)
as well as of lime carbonates: but if blued only after twenty minutes
or more, it would indicate the presence of the carbonates of lime and
magnesia. If not changed at all, the conclusion would be that either
lime carbonate is in very small supply, or that the soil is in an acid
condition. (See chapter 8, p. 122).
_Saline and Alkali Soils._—The presence of an unusual or injurious
amount of _soluble salts_, as in the case of sea-coast and alkali
soils, is commonly easily ascertained in the field; where, if the
surface soil is at all seriously contaminated with soluble salts of any
kind, these may be seen on the surface during a dry season, forming a
whitish efflorescence, which in most cases is definitely crystalline.
In doubtful cases a tablespoonful of the surface soil may be leached
with water, and the first ten or fifteen drops caught in a clean,
bright silver spoon and evaporated. Or the soil may be stirred up with
about twice its bulk of water and the mixture be allowed to clear by
settling, then evaporating. A slight whitish film will almost always
remain in the spoon; but if the amount be somewhat considerable, the
presence of soluble salts is very readily recognized by pouring a
few drops of clear water on one side of the spot, and then allowing
it to flow gently over the spot to another place, where it is again
slowly evaporated. Any considerable amount of salts present will be
shown both in the diminution of the original spot, and in the soluble
residue accumulated where the water was last evaporated. Should _common
salt_ be present to any considerable extent, the residue in the silver
spoon will, if the last drops be allowed to evaporate slowly, show
square or cubical crystals to the naked eye, and certainly to a common
pocket lens. The residue may also be tested with red litmus paper for
carbonate of soda, which would quickly turn it blue.
More detailed examination requires chemical reagents and experience,
but the above tests should be sufficient to prevent the mistaking of
mere white spots, whose humus has been destroyed by fermentation caused
by bad drainage, with true alkali caused by excess of soluble salts; a
mistake not uncommon in both the arid and humid regions.
APPENDIX C.
SHORT APPROXIMATE METHODS OF SOIL EXAMINATION USED AT THE CALIFORNIA
EXPERIMENT STATION.
BY R. H. LOUGHRIDGE.
The California Experiment Station has for many years given the farmers
of the State the privilege of having their soils examined to ascertain
any physical defects, deficiency in plant-food, or the presence of
alkali salts. They have quite generally taken advantage of this, and
the number of samples of soil sent in each year has been very large.
A complete analysis of a soil-sample requires fully 15 days; hence the
necessity of adopting some quick methods for the determination of the
main elements of fertility, viz., humus, lime, potash, and phosphoric
acid, that would at the same time give results sufficiently accurate
for practical purposes. Similarly for alkali salts in the soil; the
leaching-out and analysis of which often occupies more than a week.
The following methods have been adopted, which shorten the time of
examination for the plant-food of a soil to about one hour, except for
potash, which requires a much longer time. For alkali salts the time is
reduced to two days, and less if a pressure filter be used.
_Humus._—The Grandeau method of ammonia extraction requires the removal
of the lime and magnesia with weak hydrochloric acid, washing out of
the acid and then digestion with weak ammonia; all of which, with a
soil rich in humus, may require many days, though a number of samples
may be put through at the same time.
The method adopted to determine adequacy or inadequacy of the humus
(for this is all that is intended in this examination) is completed in
less than half an hour. It is based on the color of the humus-extract
and avoids the necessity of removal of the lime from the soil.
The soil is pulverized in a mortar with a rubber pestle, and passed
through a half-millimeter sieve. Seven grams of the fine earth is
placed in a test tube with 15 or 20 cc. of a ten per cent solution of
caustic potash and boiled for ten or fifteen seconds, then allowed to
settle. The humus is dissolved and the density of the color of the
solution is an indication of adequacy or inadequacy. A dense black,
non-translucent solution shows the presence of at least one per cent
of humus in the soil; a deep brown translucent color indicates about
one-half of one per cent; while a light brown color clearly shows a
deficiency in the soil, and a need of a good green-manure crop.
_Lime._—Two grams of fine earth is treated with a little hydrochloric
acid, boiled for a few seconds, and ammonia is added to precipitate
the iron and alumina; the whole, with the soil-residue, is quickly
thrown on a filter to separate the mass from the lime solution, and
washed. After adding ammonium chlorid the lime is precipitated with
oxalate of ammonia, and its adequacy for soil-fertility judged of by
the turbidity of the solution, or the bulk of the precipitate. Or the
latter may be filtered off, dried and weighed. We thus obtain a measure
of the carbonate and humate of lime present, by comparing it with the
precipitate obtained from a soil whose percentage of lime has been
correctly ascertained.
_Potash._—The determination of potash in the soils requires more time
than either of the other ingredients, and is more rarely made by us.
Our knowledge of the soils of the State of California obtained through
many analyses, gives us a clue to those localities where potash would
probably be deficient, as well as to those whose soils are generally
extremely rich in potash; the percentages reaching usually from .5 to
as much as 1.5 per cent and more.
For the determination, two grams of the fine earth is digested in
hydrochloric acid over a steam bath for two days, the insoluble residue
filtered off, the filtrate evaporated to dryness to render the silica
insoluble, again filtered and the iron; alumina and lime removed by
precipitation with ammonia and oxalate of ammonia and filtration. The
filtrate is then evaporated to dryness, the ammonia salts destroyed
with _aqua regia_ or driven off by heat, and the alkalies changed to
chlorids. Any residue is then filtered off and platin-chlorid added to
precipitate the potash, which is separated and determined in the usual
way, either by reduction of the platinum by ignition, or by measurement
in a Plattner’s potash tube.
_Phosphoric Acid._—The determination of phosphoric acid is based on
the volume of the phospho-molybdate precipitate in a tube made like a
Plattner’s potash tube, but having a wider interior diameter for the
smaller portion (not greater than 3 millimeters), and a length of 50
mm. With this diameter, one mm. in height of the precipitate obtained
by our short method indicates one one-hundredth of one per cent of
phosphoric acid in the soil. The unit of measure must be obtained
for each tube, unless of uniform diameter, and is ascertained by
taking a soil whose phosphoric-acid percentage has been determined
gravimetrically and giving it the following quick treatment; which
must, of course, be closely followed in each soil to be examined.
Two grams of the fine earth is ignited in a platinum dish to destroy
the organic matter, transferred to a test-tube containing 5 cc. of
nitric acid and made to boil for only a couple of seconds, thus
preventing the solution of silicates to any material extent. It is not
allowed to stand, but a little water is immediately added and it is
quickly thrown on a small filter and washed with a little water. The
phosphoric acid is then precipitated with molybdic acid at the proper
temperature; allowing it to settle, the liquid is drawn off and the
precipitate transferred to the measuring-tube. It settles into the
small part in a short time if the latter is not too narrow, and is then
measured with a millimeter scale. This represents the percentage as
found in the soil by the gravimetric method, and serves as a guide for
other examinations, whose agreement with gravimetric determinations is
generally quite close, and quite sufficient for practical purposes.
The rapidity with which the solution is made and separated from the
soil is a matter of special importance for comparative results, or
determination of percentages; for if the acid solution be allowed to
stand for some time before filtration from the soil, silica passes into
solution also, and the volume of the molybdate precipitate is increased
by it; thus vitiating the results and adding to the time required for
the method. By this short method the practically important phosphoric
acid in the soil may be approximately determined within half an hour.
SHORT METHOD FOR ALKALI SALTS.
The old method of obtaining solutions of the salts by leaching the
soil on a filter until all of the alkali had been washed out has been
replaced by the following short one. 50 or 100 grams of the well-mixed
soil is placed in a bottle containing 200 cc. of water, shaken up
occasionally during 12 hours and allowed to settle. The solution may
then be passed through a common filter (or preferably a pressure
filter) and an aliquot part (usually 50 cc.) of the filtrate evaporated
to dryness in a platinum basin and ignited at a temperature just below
redness to destroy any organic matter that may be present. The basin
and contents are weighed and the soluble salts are dissolved in a very
little water and separated by filtration through a small filter into a
50 cc. cylinder and the alkali carbonates and chlorids determined by
titration, being calculated as sodium compounds.
The material remaining on the filter and in the basin, consisting of
insoluble earth, carbonates and calcium sulfate, is gently ignited
in the basin and weighed; the difference between this and the first
weight gives approximately the _total soluble salts_, which should
substantially correspond to the titrations made.
The sulfates are determined by differences between these and the total
alkalies. The solution may contain some sulfate of magnesia, or calcium
and magnesium chlorids, and these are determined gravimetrically.
Nitrates, which may have been destroyed in the first ignition, are
determined in the original solution by the picric method. Any magnesia
rendered insoluble by the ignition may usually be accounted for as
chlorid, unless much nitrate is present which is rarely the case in
carbonated alkali. If much nitric acid was found, it should be first
assigned to magnesia.
INDEX.
A.
PAGE
Absorption and movements of water in soils, 221
of solids from solutions, 267
of gases by soils, 272, 275
Acacias, tolerance of alkali, 480
Accessory minerals, 50
Acid, strength used in soil analysis, 341
Acidic and basic eruptive and metamorphic rocks, 49
Acidity, neutrality, alkalinity of soils, 322
Acids of different strengths, analysis with; table, 326, 341
Action of plants in soil formation, mechanical and chemical, 19
Aeration and reduction as influencing nitrification, 147
effects of insufficient, in soils, 280
excessive, injury in arid regions, 280
Aerobic and anerobic bacteria, 144
Air, functions in soils, 279
“ of soils, composition of, 280
Air-space in soils; figure, 108
Alabama, vegetation and soil-characters, 511
Alaska current, effects on California climate, 296
Alinit, 149
Alkali carbonates and sulfates, inverse ratio, 451, 452
carbonates, effects on clay, 62
effects on culture plants; figure, 426, 427
Alkali-heath, range, tolerance of alkali, figure, 544, 545
Alkali lands, crops for strong, 468
effects of irrigation on, 428
efficacy of shading, 457
exceptionally productive when reclaimed, 483
fertilization not needed in, 483
formation from leachings of slopes, 453
geographical distribution of, 423
high and lasting production when reclaimed, 482
inducements toward reclamation of, 481
in the San Joaquin valley, Cal., figure, 425
possible injury to, from excessive leaching, 462
Alkali lands, summary of conclusions, 453
surface and substrata of, 429
utilization and reclamation of, 455
of world-wide importance, 424
vegetation of, 534
Alkali-resistant crops, 455
Alkali salts, black and white, 441
composition of, 439
composition of; general table, 442, 443
distribution in heavy lands, 436, 437
effects on beet crop, 465
horizontal distribution of, 439
in hill lands, 439
in sandy lands, 433, 435
in Salton Basin, distribution of, 4, 36, 438
leaching-down of, 459
nature of, 423
plant food in, 441, 444
reactions between, 449, 450
reduction by cropping, 463
relative injuriousness of, 464
removal from the soil, 458
removal by deep-furrow irrigation; figure, 460, 461
tolerance of various crop plants; table, 466, 467
total in lands; estimation of, 444
underdrainage the universal remedy for, 460
upward translocation from irrigation, 433
vertical distribution in soils, 429, 431, 432, 434
Alkali soils and seashore lands, 422
calcareous character of, 28
composition of, as a whole, 445, 446, 447
how native plants live in, 430
origin of, 422
repellent aspect, cause of, 424
retention of silica in, 392
Alkali spots, white, 286
Alkali, rise of, 428
turning under of surface, 456
weeds as cattle food, 468
study of, by Loughridge and Davy, 535
Aluminic hydrate, in soils of California and Mississippi;
table 101, 390
Alluvial soils, 12
Ammonia-forming bacteria, 149
Ammonia gas, absorption of, by soils; figure, 274, 275
Ammonic carbonate, effects on glass, 18
Ancient civilizations, preference for arid countries, 417
rare in humid countries, 418
Apatite, 63
Arid and humid climates, rock-weathering in, 47
Arid and humid regions, criteria of soils of, 371
contrast between soils of, 28
soils of, 111, 371
Arid and humid soils, general comparison; table, 375, 377
Arid belts, subtropic, 298, 299
utilization of, 299
Arid conditions, local, in tropical countries, 401
Aridity, influence upon civilization, 417
Arid region, bunch grasses on soils of, 111
standing hay in, 300
upland soils of; table, 373, 374
Arid soils, productiveness induces permanent civil organization, 412
Arroyo Grande and Yazoo buckshot soils, 345
Asparagus, resistant to salts, 475
Atmosphere, composition of; table, 16
Azotobacter, 156
Lipman on, 156
B.
Bacteria, active in soil-formation, 20
aerobic and anaerobic, 144
denitrifying, 148
food and functions of, 145
in soils, numbers of, 142
micro-organisms of soils, 142
multiplication of, 144
nitrifying, 146
Bacterial life, effect on soil, condition, 149
relation of carbonic dioxid to, 281
Bacteroids, 151
Mork figures, 152, 153
Basaltic rocks, 49
Basalts, red soils from, 52
Basic slag, 64
Basin irrigation, advantages of, 243
Bauxite in soils, 101, 390
Beet, sugar, effects of salts on, 474
tolerant of common salt, 474
Bhil soils, 414
Bicarbonate of soda, 78
Black-alkali lands, difficulty in draining, 462
neutralizing of, 457
waters, use of, 250
why so called, 78
Black earth of Russia, humus in; table, 130
Black sand, 45
Black prairie soils, 53
Black soils and lands, 283
Blizzards in continental America, 298
Blown-out lands, 9
Blue tint in clays and subsoils, 45
Bodengare, 149, 150, 281
Bog ore, formation of, in subsoils, 46, 66
Bones, composition of, 64
Bone meal, efficacy of, 65
Borax, borate of soda, 79
Bottom water, 227
rise of, from irrigation, 227, 230
Bottoms, first and second, contrast between, 506, 507, 509
Bottoms, first, tree growth of, 507, 509
Brahmaputra alluvium, Assam, 413
Brown iron ore, 44
“Buckshot” soils of Yazoo bottom, 116
“Bunch grasses” as alkali-resistants, 471
Burning-out of humus, effects of, 118
Burrowing animals, work in soil-formation, 160
C.
Calcareous clay, crumbling on drying, 116
formations, predominance in Europe, 525
soils, definition of, 367, 496, 524
solubility of alumina and silica in, 389
subsoils, and hardpans, 162
Calciphile, calcifuge and silicophile plants, 521
Calcite, calcareous spar, 39
recognition of, 39
Caliche, in Chile, Nevada, and California, 66, 67
Capillarity, 189
Capillary water, reserve of, 229
rise of, 202 to 207
Carbonated water, action on feldspar, 32
action on silicates, 18
universal solvent, 17
Carbonate of soda, 77
injury to soils and plants, 78
Carbonates, chlorids and sulfates of earths and alkalies,
reactions between, 449, 450
Carbonic acid, 17
secreted by roots, 20
Carbonic dioxid, absorption of, by soils, 274
heavily absorbed by ferric and aluminic hydrates, 278
occurrence, formation, 17
relation to fungous activity, 281
Cascade range, climatic divide in N. W. America, 297
Caves in limestone regions, 41
Celery, moderate tolerance of alkali, 475
Centrifugal elutriator, Yoder’s, 92
Cereals, alkali-resistance, barley, gluten wheats, 471
Channels, cutting-out by gravel, 6
Charcoal, absorption of gases by, 276, 277
Chemical absorption by soils, 270
action of roots, 20
analysis of soils (in general), 323
character of soil, recognition of, 322
decomposition, causes intensifying, 21
processes of soil formation, 16
Chile saltpeter, 66
Chernozem, 130
analyses of, table, 364
Chestnut, American, a calcifuge tree, 491, 519
Chlorin, largest ingredient of sea water, 27
Chlorite, 36
Chlorosis of vines in marly lands, 526
Churn elutriator, Hilgard’s; figure, 91
Circling of hill lands, 220
Citrus fruits, injury to, from alkali, 478
lemons most sensitive, 478
sensitiveness to common salt, 477
Classification of rocks, 47
of soils, 10
Clay as a soil ingredient, 83
colloidal, 59
functions of, in soils, 59
maintains crumb structure, 110
Clays, claystones, clay shales, 48
colors of, 58
formation, flocculation and deposition of, 33
maturing of, 60
plasticity and adhesiveness, influence of fine powders on, 85
influence of ferric hydrate on, 85
Clay-sandstones, soils from, 57
Clays, separation of, by subsidence, by centrifuge, 89
varieties, enumeration of, and characters, 57, 58
fusibility of, 58
Claystones, soils from, 59
Cleavage of rocks, 3
Cleopatra’s needle, 2
Climate, 287
Climatic and seasonal conditions, 21
Climates, continental, coast and insular, 297
Coffee soils, calcareous, 417
Colloidal clay, amount in soils. Table, 84
analysis of, by Loughridge, 385
effects of alkali carbonates upon, 62
investigation by Schloesing, 59
properties of, 61
separation of, by boiling and kneading, 61
Colloid humates, 133
Colluvial soils, 12
Colors of soils, advantages of, 283
Common salt, injuriousness in soils, 76
recognition of, 76
removal from soils, 76
Conglomerates, 48
Conifers, tall growth of, in arid regions, 517
Contraction of soils in wetting and drying, 114
Co-operation, favored by need of irrigation, 419
Corsican and maritime pine, ash analyses, 520
Cotton, compact growth and heavy boiling on calcareous soils, 503
Cracking of clay soils in drying, 113
Cressa; range, tolerance of alkali, figure, 545, 546
Creep, 12
Crops, alkali-resistant, 455
Crumbling of calcareous clays on drying, 116
Crumb-structure of soils; figure, 110
Crusting of soils, effects of, 111, 117, 221
Cultivated soils, analysis of, 325
investigation of, 316
Cultural experience the final test, 324
Cutting-out of channels by water-borne gravel, 6
Cypress, different forms of; figures, 507, 508
D.
Date palm, resistance to alkali, 478
Decomposition, chemical, of rocks, 16
Decolorizing action, of soils, charcoal, 267
Deep-rooting of native plants in arid region, 174
Deforestation, effects of, 219
Deltas, formation of, 7
Denitrifying bacteria, 148
Deserts, effects of winds in, 8
Desert sands, only lack water to become productive, 420
Dew, formation of, 307
rarely adds moisture to soils, 308
within the soil, 308
Differentiation of soil and subsoil, causes of, 121
Distance between furrows and ditches, 241
Dolomite, 42
Drainage, rights-of-way for, 461
Drainage waters, use for irrigation, 250
Drain waters, analyses of, table, 22
leaching effects of, 271
Drouth, resistance to, in arid soils, 167
Dust soils, nature of, 104
slow penetration of water in, 105
Dust storms, 9
Dynamite, used for shattering dense substrata, 181
E.
Earth’s crust, known thickness, xxiv
Earthworms, action of in soil-formation, 158
Ecological studies, 314
Egypt, obelisks of, 2
Elements constituting earth’s crust, table of, xxiv
important to agriculture, list of, xxiv
Elutriator, Hilgard’s, figure, 91
Epsomite, epsom salt, in soil, 78
Eremacausis, 129
Erosion in arid regions, 219
in Mississippi table lands; figures, 218
lowering of land by, 15
of rocks by sand; figure, 10
Eruptive rocks, basic and acidic, 49
rocks, soils from, 52
Eucalyptus, tolerance of alkali, 480
European observations on plant distribution, 519
standards of plant-food adequacy—Maercker’s table, 369
Europe, predominance of calcareous formations in, 525
Evaporation and crop yields, calculated, 193
and crop yields, observed (Fortier), 194
and plant growth, 193
counteracting, in alkali lands, 455
dependence on air temperature; Fortier’s experiments, table, 255
from reservoirs and ditches, 257
from water surfaces, 254
wet and moist soils, 254
in different climates, 192, 256
in different localities, California, 255
restrained by loose surface layer, 255
through roots and leaves, amount of, 262, 263
Expansion by oxidation, 18
F.
Farmyard or stable manure, 72
Feldspars, weathering of, 31
products of, 32
Ferghana, alkali lands in, 441
Ferric hydrate, effects of, 100
functions of, in soils, 285
high absorptive power of, 277
in Hawaiian soils; table, 356
more diffused in humid than in arid soils, 392
Ferric phosphate, unavailability of, 356
Ferroso-ferric hydrate and oxid, 18, 45
Ferrous oxid, 18
Ferruginous lands, injury from swamping of, 233
Fertilizers, mineral, 63
waste of, by leaching, 269
Flocculation and floccules, 91
Flocculated structure; cements maintaining, 110, 111
Flood-plains of rivers, 14, 15
Fool’s gold, 75
Force exerted by roots, 19
Forecasts, general, of soil quality in forest lands, 507
of soil values, popular, 313
Forest trees, forms of, 499 to 502
of Atlantic states on alkali lands, 481
Form and development of trees, differences in, 498
Forms of leaves, variation in, 502
black-jack oak, 499, 501
post oak, 499, 500
trees, deciduous, in arid region, 516
willow, scarlet, black and Spanish oaks, 502
Freezing water, effects of, 3
Frost, effect of soils, 118
Fruiting, favored by lime in soils, 503
Fungi and molds, action of, 123
functions in humus-formation, 157
G.
Gases, absorption of, by soils, 272, 275
partial pressure of, 276
Germination of seeds, 309
Glacier flour, fineness and fertility of, 5
physical analysis of, 5
Glaciers, grinding and abrasion by; figure, 3
Glauber’s salt, 77
Glauconite, in calcareous sandstones, 56
Gneiss soils, 51
Gobi desert, migration of lakes, 9
Going-back of orchards, 182
Grain-sizes, effect on percolation; table, 224
influence on soil texture, 100
Grandeau method of humus estimation, 132
Granite soils, potash and phosphoric acid in, 50
Granitic rocks, weathering of, 47
sand, formation in arid climates, 2
Grano-diorite soils, of Sierra Nevada, 51
Granular sediments, influence upon tilling qualities, 102
Grape-vine, alkali, tolerance of, 475
Grasses, cultivated, sensitive to alkali, 471
Greasewood, range, tolerance of alkali; figure, 542, 543
Greenstones, soils from, 51
Ground water, depth most favorable to crops, 228
variation of surface of, 228
Gulf-stream, 295
Gypsum or selenite, formation from sea-water evaporation, 42
how recognized, 42
H.
Halite, 76
Hardpans, causes, formation and cements of, 185
Hardpan, physical, analysis of, 103
plowsole, 241
Hawaiian Islands, humid and arid sides of, 297
soils, analyses of, 356
Hay bacillus; figure, 149, 150
Heat and cold, effects on rocks, 1
of high and low intensity, 304
reflection and dispersion from soil surface, 304
relations to soils and plant growth, 301
trapping of suns, 288
Heaviest clay soils, physical analysis of, 115
Heaving-out of grain, 119
Hematite, 44
Herbaceous plants as soil indicators, 517
Hog-wallows, 114
Hornblende and pyroxene, 33
weathering of, 33
Horsetail rushes, secretion of silica by, 31
Humates and ulmates, 133
cementing effects of, 111
Humid and arid climates, rock-weathering in, 47
Humid region, upland soils of; table, 372, 374
Humification in soils, 20
normal conditions of, 129
tests; Snyder, tables, 140
Humin substances, formation of, 123
Humus, amidic constitution of, 125
and coal, amounts of, from vegetable substance, 128
amount in soils, 133
ash of, from Minnesota soils, analysis, 134
decrease of nitrogen-content with depth, 135
determination in soils, 132
distribution in the surface soil, 157
functions in soils, 21
in arid and humid regions, 138
in black earth of Russia, 130
in Minnesota soils, 131
in North Dakota soils, 133
in the surface soil, 120
losses from cultivation and fallow, 131
nitrogen of, 124, 135
percentage in soils, and nitrogen-content of,
tables, 135, 136, 137
porosity of, 124
progressive changes in soils, 126
relation to bacterial content, 144
scanty in arid soils, but rich in nitrogen, 397
substances, physical and chemical nature of, 124
variation of, with original materials, 139
volume weight of, table, 125
versus adipocere, 140
Hydraulic elutriation, 90
Hydromica, 35
Hydrous silicates in soils of arid region, 388
I.
Ice-flowers on soils, 119
Immediate plant-food requirements, ascertainment of, 333
productiveness, chemical tests of, 337
productiveness vs. permanent value of soils, 318, 327
India, climatic contrasts, 401
Indian soils, table of analyses, 410 412
types of soils, 411
Indo-Gangetic plain; calcareous hardpan, kankar, 411
Injury from excessive runoff, prevention of, 220
to plants from the various salts, 531
to soils and plants from carbonate of soda, 78
Insects, work in soil-formation, 160
Insoluble residue of soils; less in arid than humid, 384
Insufficient rainfall, leaves sea salts in soils, 28
Insular climate, of Britain, western Europe, 298
Introduction, xxiii
Injury from swamping, permanent, 232
Iron carbonate solution, how formed, 44
coloring clays, 58
minerals, 44
pyrite, how recognized, 75
Irrigation, basin, advantages and disadvantages, 244
by check flooding, 237
flooding, 237
furrows, 238
lateral seepage, 242, 241
shallow, deep and wide furrows; diagram, 239
surface sprinkling, 237
underground pipes, 245
ditches, leaky, effects on alkali lands, 429
excessive surface rooting caused by, 245
methods of, 236
necessitates co-operation, 419
Irrigation water, abundant use of saline, 249
duty of, 251
economy in use of, 243
effects of saline, figures, 247
heavy losses in using, 252
limits of salinity, 246, 248
loss by evaporation, 252
loss by percolation; diagram, 253
quality of, 246
saline, how to use, 249
testing penetration of, 242
temperature of, 244
Irrigation, winter, advantages of, 236
Isinglass, 43
J.
Janesville loam, chemical analysis of, 331
Japan current, 296
Jasper and hornstone pebbles, weathering of, 30
K.
Kainit, composition of, 71
Kaolinite and clay; kaolin, 32
assumes plasticity on trituration with water, 60
crystalline form of, 22, 59
lacks plasticity, 60
Kaolinization, results in zeolite-formation, 395
slow in arid regions, 87, 386
L.
Landholding, units of, smaller in arid than in humid region, 420
Landlocked lakes, water of, 27
Land plaster as a fertilizer; effects on soils, 43
Landslides, 12
Laterite soils, Wohltmann’s definition, 416
Terra roxa of Brazil, 416
Leaching of the land, 22
Legumes, bacteria of, 150
mostly sensitive to alkali, 472
Leguminous plants, mostly calciphile; exceptions, 518
Leucite, potash content, 32
Lichens, action on rock-surfaces, 19, 20
Lignites and coal, how formed, 127
Lime a dominant factor in productiveness, 353
Lime carbonate in sea water, 26, 27
removed from earth’s surface, 41
summary of effects in soils, 379
Lime-content, effects of high, in soils, 365
effects on availability of phosophates, table, 366
“Lime-country is a rich country”, 365
Lime, excess of, in arid soils, 378
Lime feldspars, leave lime carbonate in soils, 32
in alkali lands protects plants from salts, 532
lands, failure of tea on, 414
Lime-loving trees, 490 to 492, 497
Lime, most abundantly leached out, 24
percentages, what are adequate, 367
in coast-belt soils, 496, 497
in heavy clay soils; table, 368
Lime renders lower amounts of plant-food adequate, 354
Limestone countries, 53
Rotten, 54
soils, excluded from comparison of arid and humid soils, 376
residual, 53
Limestones, impure, as soil-formers, 40, 53
residual soils of, how formed, 40
soft, or marls, 40
slow disintegration of pure, 63
Limit of acid action on soils, investigation of, by Loughridge, 340
Limonite, 44
Loamy and sandy soils, show little shrinkage, 117
Loose surface layer, illustration of effect, figure, 258, 260
prevention of evaporation by, 257
Loss of humus in summer mulch, 132
Louisiana, vegetation and soil-characters, 512
Lowland tree-growth, 506
Lysimeter, 227
M.
Madagascar, character and soils of, 405, 406
climate and rocks of, 406
methods used by Müntz and Rousseaux, 406
potash and lime leached into valleys, 407
red soils, 407, 409
table of soil analyses, 408
Madras, red soils of, 415
Magnesia, effects of excess over lime, 382
exceeds lime in tropical soils, 405
high in arid soils, 381
leached out next to lime, 24
proper proportions to lime, 383
Magnesian limestones as soil-formers, 42
Magnesian soils largely poor, 36
Magnetite, 45
Maize and sorghums, alkali-resistance, 471
Maize roots in humid and arid region, 175, 176
Manganese, more in humid than arid soils, 383
stimulant effects on crops, 383
Marble and limestones, formation of, 39
Marls, gypseous and calcareous, 43
Marly substrata, 186
Marine saline lands, 527
first crops for, 533
reclamation for culture, 534
Matière noire; active nitrification of, 132, 360
Mechanical analysis of soils, 88
Melilots, white and yellow, alkali resistance, 473
Mesas of arid region, 14
Mesopotamia, rehabilitation of, 421
Metamorphic rocks, 46
Methods of irrigation, 236
soil analysis, 325
Mica as a soil ingredient, 35
weathers slowly, 35
mistaken for gold and silver, 35
Mica-schist soils, 51
Micro-organisms of soils, 142
Mineral fertilizers, 63
ingredients of soils, minor, 63
Minerals injurious to agriculture, 73
major soil-forming, and rock-forming, list of, 29
tints of, 18
unessential or injurious to soils, 75
Mirabilite, 77
Mississippi, changes in vegetation from east to west in northern, 490
investigations in, by writer, 489
northern, vegetative belts in; map, 490
vegetative belts, descriptions of, 490, 491, 492
Mississippi river, sediment carried by, 7
Mississippi, southern, central prairie, long-leaf-pine belts, 493
coast-belt; pine meadows; profile, 495
live-oak or shell hammocks, 495
Mississippi valley, climate of, 298
Mississippi water, annual variations in, 25
generalized composition of, 25
Modiola, of Chile, 469
Moisture hygroscopic, table, 196
influence of temperature and air-saturation, 197
method of determining, 197, 198
Mitscherlich’s objections, 199
utility to plant growth, 199
available to growing plants, 211
distribution in soil, as affected by vegetation, 264
evaporated from forests, 265
Eucalyptus, 265
in Russian forests and steppes, 265
requirements of crops in the arid region, 212
Loughridge’s tables of same, 214
supplied by tap roots, 229
useful to crops retained by alkali lands, 433
wasted by weeds, 264
Moraines, in North Central states, 5
Mosses, follow lichens in rock decomposition, 20
Moulds and fungi, action of, 123
Mountain chains, arid climate under lee of, 294
effects of, on rainfall, 293
Muddy waters, 251
Muir glacier, analysis of mud, 5
Mulches, loss of humus, 132
Mulching with straw, sand, 266
Mustard family, sensitive to alkali, 473
Myrobalan root, use for grafting in alkali lands, 479
N.
Native vegetation, basis of land values for farmers, 488
causes governing its distribution not an unsolvable problem, 489
result of struggle for existence, 487
Native grasses for alkali lands, 470
Native growth, cogency of conclusions based on, 314
New Mexico, soils from; analysis, 378
Nile water, Letheby’s analyses of, 25
Nitrate deposits, origin of, 67
of soda, 66
Nitrates, waste of, by leaching, 24, 68
Nitrification, active in matière noire, 360
Nitrification and denitrification, 145
in alkali lands, 68
in soil of “ten-acre tract.”, 359
intensity in arid climates, 68
list of substances favoring, 147
of organic matter in soils, experiments, 358
not active in unhumified matter, 359, 360
Nitrifying Bacteria, 146
Nitrobacterium; conditions of activity, 146
Nitrogen-absorbing bacteria, 156
Nitrogen, absorbed more abundantly than oxygen, 278
accumulation of, in humus, 124
adequacy in humus, lowest limit of, 363
in soils, 357
availability of, in soils; ascertainable, 363
content of humus, 135
deficiency, pot test, figure, 362
determination of, in soils, 357
hungry soils; table, 361
percentages in humus, what are adequate, 360
supply of plants, views on, 150
Nitrosomonas, figure, 246
Nodules of legumes, 151
North Central States, herbaceous vegetation on
calcareous soils, 514, 515
lowland growth in uplands, when, 515
vegetation and soil-character, 513
Nutritive salts in alkali, 441
O.
Ocean currents, Gulf stream and Japan stream, 295, 296
Olive, resistance to alkali, 478
Organic and organized constituents of soils, 120
Organisms influencing soil-conditions, 142
Oxalic acid, secretion by lichens, 19
Oxidation, expansion by, 18
Oxids constituting earth’s crust; table, 31
Oxygen, action in weathering rocks, 18
proportion of, in earth’s crust, 30
P.
Pamperos, 9
Peat bogs, 122
Peaty soil, shrinkage, 117
Percolation in natural soils: diagram, 223, 225, 226
rate of, as influenced by grain-sizes, 224
Permanent value of land vs. Immediate productiveness, 340
Physical and chemical causes of vegetative features, 505
conditions of plant growth, 319
Physical analyses, correlation with popular names, 96
results of, 94
table. Mississippi and California soils, 98
analysis of soils, 88
constituents of soils, 10
Physico-chemical investigation of soils, 313
Physiological soil analysis, 333
Phosphate fertilizers, importance of, 65
Phosphate fertilization, in arid region, 393
in California, 393
Phosphoric acid, limits of adequacy in soils, 355
minute amounts leached from soils, 24
no constant difference between arid and humid soils, 393
rendered inert by ferric hydrate, 355
Phosphorites, low-grade, of Nevada, Russia, 63, 64
Plane tree, oriental, resistant to alkali, 480
Plant-adaptation “varying from province to province”, 523
Plant associations, plant formations, 315
Plant distribution, Thurman’s physical theory of, 519
Plant-development under different temperatures, 309
Plant-food, accumulation in finest parts of soils, 87
high percentages mean high land value, 346
ingredients, condition of, in soils, 319
in virgin soils, lowest limit of, table, 352
limits of adequacy, 353
minute amounts may produce large crops, 410
percentages, what are high, 346
percentages, low, 346
water-soluble, reserve, unavailable, 320
Plant-growth on arid subsoils, 166
Plants, deep-rooting in arid region, 174
indicating irreclaimable alkali lands, 535, 536
Plant root action, cannot be imitated in laboratory, 324
Plasticity, absence of, in fine powders, 60
of clay, causes of, 60
lost by burning, 60
Plot tests, difficulties and uncertainties of, 334
plan of, figure, 335
Plowsole, how formed, by shallow irrigation, 186, 241
Poor chalk lands, 525
Pore-space, 108
Porosity of humus, 124
Port Hudson bluff, lignite in, figure, 128
recession of, 116
Potash, abundant in arid soils, 395
and soda in arid and humid region, 394
Potashes, production of detrimental to agriculture, 69
Potash feldspar, supplies potash to soils, 32
fertilization first in humid, last in arid region, 396
from sea water, 69
limits of adequacy in soils, 354
minerals, orthoclase feldspar, 68
preferential retention of, in soils, 272
Salts, Stassfurt, 69
slightly leached out, 24
sulfate, high-grade, 71
Pot-culture tests, 336
Powders, absorption of various gases by, table, 277
Prairie soils, black, 53
Preparation of soils for physical analysis, 89
Productive capacity and duration, forecast of, 346
Progress of humification and formation of coal, table, 126, 127
Pulverulent soils of arid regions, 87
Purifying action of soils, 269
Putrefactive processes, relation to carbonic gas and
anaerobic bacteria, 282
Putty soils, 103
Pyroxene, augite, 33, 34
Q.
Qualifications required for soil study, 524
Quality of irrigation water, 246
Quince, resistance to alkali, 479
Quartz and allied rocks, 29
sand most prominent ingredient of soils, 30
veins, formation of, 31
R.
Rain belts, temperate and tropical, 295
Rainfall, amount of, 215
distribution in California and Montana, 290
in the United States, 215
most important, 290
on the globe, figure, 294
influence on soil formation, 22
insufficient, forms alkali soils, 28
leaves lime behind, 28
natural disposition of, 216
Rains, beating, 221
cold and warm, 302
Reclaimable and irreclaimable alkali lands, 534
Red foothill soils of California, 34
Red or rust-colored soils, 34
advantages of, 284
Regur soils, Deccan, India, 414
formation of, 415
“guvarayi” hardpan, 415
present production, 414
Reh of India, 440
Reserve plant-food in soils, 320
of zeolites, carbonates, phosphates, 321
Residual soils, 11, 13, 22
Rhizobia, adaptation to symbiosis, 154
inoculation of soils with, 154
increase of crops by inoculation with, 155
of legumes, 150
mode of infection, 154
varieties of forms, 154
Rhubarb, sensitive to alkali, 475
Rhyolites, soils from, 53
River bars, formation of, 7
Rivers, amount of dissolved matters carried by, 24
flood-plains of, 13, 14
sediment carried by, 24
waters, analyses of, table, discussion, 23, 24
white and green, 4
Rock crystal, 29
Rocks as soil-formers, 47
chemical decomposition of, 16
cleavage of, 3
definition of, xxiii
disintegration of, under extremes of temperature, 2
effects of heat and cold on, 1
erosion of by sand, 10
forming minerals, 29
fragments, rounding of, by flowing water, 6
Rock powder, 85
Rock-weathering in arid and humid climates, 47
Rohhumus, 122
Rolling of soils, of influence of, on heat, 305
Root action, limitation of, 351
Root bacillus, figure, 149, 150
Root crops, effects of alkali upon, 474
Root development in the arid and humid regions, 169 to 176
Rooting, deep, from proper irrigation, 243, 245
Roots, chemical action of, 21
force exerted by, 19
secrete carbonic acid, 20
Root system in the humid region; figure, 168
Rotten Limestone, soils from, analyses, 54
Runoff of rain water, 216
Russia, black earth of; roots and humus in, 130, 363
Rye grass, giant, of Northwest; uses, 470
S.
Saline and alkali lands, vegetation of, 527
plants, analyses of ashes of, 530
selective power of, 531
Saline and xerophile vegetation, similarity of, 528
Saline contents of waters, variations of, 250
solutions, structural and functional differences caused by, 528
vegetation, general character of, 527
Saltbushes, Australian, growth and use in California, 469
of Great Basin, probable usefulness, 468
Saltgrass; range, tolerance of alkali, figure, 546, 547
Salton Basin, profile of salts in, 438
Salts, absorption of, by saline plants, 529
Saltwort: range, tolerance of alkali, figure, 540, 542
Samoa and Kamerun soils, analyses by Wohltmann; method, 402
table of, 404
Samphire, Bushy and Dwarf; range, alkali-tolerance,
figure, 538, 539, 540
Sand blasts, effects on cobbles, 10
coarse, effect of, on clays, 105
erosion of rocks by; figure, 10
hammocks, of Gulf coast, 56
Sands of arid and humid regions, differences in, 86, 386
table of analyses, 387
Sand, silt and dust, 85
Sandstones, 48
argillaceous, 57
calcareous, formation of, 56
rich soils from, 56
dolomitic, often form poor soils, 56
ferruginous, poor soils from, 56
siliceous, poor soils from, 55
varieties of, 55
zeolitic, soils from, 57
Sandstone soils, lightness of, 55
soils, poor, of humid region, 55
Sand storms, 9
Sandy lands, of arid regions, highly productive, 386
Sandy soils, 30
Schöne’s elutriator, figure, 90
Shrinkage, extent of, in drying soils; figure, 113, 114
Schübler on calcareous soils, 115
Sea water, average composition of, table, 26
chief ingredients useless to plants, 28
minor constituents of, 27
sources of salts in, 26
Sedentary soils, 11, 13, 40
Sedimentary rocks, 47, 48
Sediment deposited by Mississippi in Gulf, 7
Sediments, exhibition of, from physical analysis, 95, 96
number of, in physical analysis, 93
table of diameters and hydraulic values, 94
Seeds, germination of, 309
Semi-humid and semi-arid region, 377, 397
Serpentine, 36
Sieves, use in physical analysis of soils, 88
Silica, absorption and secretion by plants, 31
and alumina, soluble; quantitative relations, 385
solubility in water, 31
soluble, retained in alkali soils, 391
Silicate minerals, 31
Silicates of soda and potash, soluble, 31
Silicon, abundance of, in rocks, xxxi
Silicophile plants, a fiction, 522
Sinkholes, 43
Soapstone, 36
Soda in arid and humid regions, 394
Soda, nitrate of, 66
Sodium salts, leached out by drains and rivers, 24
Soil analysis, change of views regarding, 317
discrepant methods used in, 402
practical utility of, 318
Soil and subsoil, causes and processes of differentiation, 120
ill-defined, 120
Soil bacteria, numbers of, 141
Soil character, recognition from native vegetation, 487, 511
Soil-dilution experiments, 347
figures, 348, 349, 350
table of, 350
Soil-examination, short approximate methods for,
used at California station, 560
summary directions for, in field or farm, 556
Soil-formation influenced by rainfall, 22
physical processes of, 1
Soil-forming processes accelerated by high temperatures, 398
Soil-grains, number of, 99
surface of, 99
determination by air-flow, 99
by “Benetzungswärme”, 99
investigation, historical review of, 313
moisture, regulation and conservation of, 234
phosphates, solubility in water; Schloesing fils, 332
probe, mode of using, 177
profiles in arid and humid region, 165
Soil, samples, directions for taking, by Calif. Station, 553
sedentary or residual, 11, 13, 40
study, qualifications needed for, 524
surveys, early, of Kentucky, Arkansas and Mississippi, 316
temperature, annual range near surface in arctic
and tropical regions, 303
change with depth; table, 303
influence of evaporation on, 307
influence of soil material, 306
influence of surface conditions, 303
influence of vegetation and mulch, 305
tests by crop analysis, Godlewski, Vanderyst, 337, 338
by extraction with organic acids; Dyer, Maxwell, 339
water, different conditions of, 195
Soils, acid-soluble and water-soluble portions most important, 324
alluvial, 12, 13
ancient, in geological formations, xxix
calcareous, definition of, 367, 496, 524
classification of, figure, 11
colluvial, 12, 24
definition of, xxix
derived from various rocks, 49
effects of crusting on, 221
indefinite action of dilute acids on, 326
interpretation of analyses; Wohltmann, 403
physico-chemical investigation of, 313
(see Table of Contents)
Solar radiation, influence of, 302
Solubility, continuous, of soils in water, 328
King’s table, rich and poor soils, 330
Schultze’s table, rich soil, 328
Ulbricht’s table, poor soil, 329
Solvent action of water upon soils, 327
power of water, 17
Solubility, increased with nitrogen-content, 141
Sour grasses, 123
humus, antiseptic properties of, 122
soils, 122
Souring of soils, by cultivation, 123
Stable or farmyard manure, 72
composition of, table, 73
green-manuring only substitute, 74
method of using, in humid region, 74
physical effects of, 73
use of, in the arid region, 74
Stalactites and stalagmites, 41
Stassfurt Salts, discovery of, 69
importance to agriculture, 70
origin of, 70
Stassfurt Salts, nature of, 71
Stonecrops, succeed mosses, 20
Stone fruits, resistance to alkali, 478
Stratified rocks, derived from crystalline, 29
Stunted growth, caused by shallow or very heavy soils, 504
Sturdy growth on calcareous lands, 502, 503
Subsidence method, 89
Subsoils, arid region, 163
and deep plowing, 164
calcareous, 162
rawness of, in humid climates, 163
Substrata in arid region, importance of, 173
faulty, with figures, 177 to 180
impervious, injury from; figure, 181
leachy, 182
marly, 186
Subterranean rivers, 41
Sulfate of potash, high-grade, 71
of soda, dust from, 77
injuriousness to plants, 77
occurrence in arid regions, 77
Sulfates, reduction of, 232
Sulfuric acid in arid and humid regions, 394
Summer mulch, loss of humus in, 132
Sunflower family, resistance to alkali, 473
Sun’s heat, penetration into the soil, 302
Surface crusts, formation of, 111, 117
physical analyses of, 118
Surface, hydrostatic and ground waters, 215
Surface waters, chemical effects of percolation, 161
physical effects of percolation, 161
Swamping of alkali lands, consequences of, 451, 463
irrigated lands, results of, 231
Symbiosis, adaptation to, of Rhizobia, 154
Szek of Hungarian plain, 440
T.
Tabashir, 31
Talc and serpentine, 36
Tap-roots, moisture supplied by, 229
Tea, failure on calcareous lands, 414
Temperature, annual mean of, 289
conditions, ascertainment and presentation of, 288
extremes, on high mountains and plateaus, 288
of stellar space, 288
seasonal, monthly and daily means, 289, 291
Temporary vs. permanent productive capacity of soils, 340
Tennessee and Kentucky, vegetation and soil-character, 513
Terraces, river and lake, 14
Testing penetration of irrigation water, 242
Textile plants, tolerance of alkali, 475
Thomas or basic slag, 64
Thurman’s physical theory of plant distribution, 519
Tillage; effects of; figure, 109, 110
how maintained in nature, 111
Titanium in soils, xxxi
Time of acid-digestion, different; table, 342
Tolerance of alkali by culture plants, 463
alkali plants; table, 548, 549
Topography, influence of, on climate, 293
Trachytes, 53
Trona, Urao, 77
Tropical soils, 398
are highly leached, 400
often highly colored with iron, 400
do not need early fertilization, 399
humus in; abundant, but low in nitrogen, 399
few determinations made, 399
possible calculation of, 399
investigations of, 401
laterites, not always rich in iron, 400
mostly have low plant-food percentages, 400
resemble the “nimble penny”, 400
Tubercles of legumes, figures, 151, 154
Tufa, calcareous, 41
Tussock grass, food value of, 470
range, alkali-tolerance, figure, 536, 537
U.
Ulmin substances, 122
Underdrainage, advantages of, 235
Underdrains, effects of, 234
Unhumified organic matter does not nitrify, 148
Unhumified vegetable matter, utility of, 135, 360
United States, good field for comparative soil study, 524
Upland and lowland growth in arid and humid regions, 515
Usar lands of India, character of, 440
not all alkali lands, 440
V.
Vegetative belts, lime a governing factor of, 492
Virgin lands, advantages of soil study in, 318
Virgin soils, analysis by extraction with strong acids, 340
Vivianite, 65
Volatile part of plants, xxxii
Volcanic ash, form soils rapidly; soils from, 20, 52
Volcanic glass, 53
Volume of soils, changes on wetting and drying, 122
Volume-weight of soils, 107
W.
Walnut, black, a lime-loving tree, 490 to 497
tolerant of white alkali, 479
Washing-away and gullying of land, 217
Water, capillary, 201
ascent in soil columns, figure, 202, 205
uniform sediments, figure, 204, 207
held at different heights in soil column, table, 208
expansion and contraction in absorbing, 208, 209
maximum and minimum of water-holding power, termination of;
figure, 202, 207
movements in moist soils, 210
carbonated, solvent power, 17
carrying power, 14
controlling factor of soil temperature, 301
density of, 190
effects of flowing, 5
Water extraction of soils, practical conclusions from, 332
Water, hard, 41
hygroscopic, 196
of lan-locked lakes, 27
loss of, by irrigation in shallow furrows, 240
physical factors of, 188
regulation of temperature by, 191
relations to heat, 189
requirements of growing plants, 192
plants in arid regions, 195
sidewise penetration of, in soils, 241
of soils, chapters on, 188, 215, 234
solvent action upon soils, 327
solvent power, 17, 191
Water-soluble plant-food, 321
specific heat of, 190, 191
table, 227
vaporization of, 191
Watery soil extracts, from European soils; tables, 327, 329
American soils, King, 329, 330
Wave action on shores, figure, 7
Weathering, by oxygen, carbonic acid, water, 16, 17
“ in humid and arid regions, 2, 86
Weight of soils, per acre-foot, 107
White soils, nature of, in humid regions, 285
in arid regions, 286
Wind deposits, 105
Winds, action of, in forming soils, 8
cyclones, and anti-cyclones, 293
effects of, in deserts, 8
heat the cause of, 291
land and sea breeze, 291
trade, and monsoons, 291, 292
Winter irrigation, 236
Wire-basket tests, of Bureau of Soils, 337
X.
Xerophile vegetation, similarity to saline, 529
Y.
Yazoo bottom, soils of, 116
Yazoo “buckshot” and Arroyo Grande soils, 345
Z.
Zeolites, decomposition by acids, 36, 38, 39
exchange of bases in analcite and leucite, 37
formation of, 37
importance in soils, 38
rocks cemented by, 38
Zeolitic sandstones, 57
AUTHORS REFERRED TO.
[NOTE.—In cases where no special credit is given
in this volume for investigations made or data given from
the Southwestern States and the Pacific Coast, these should
be understood as work done, mostly under the writers
direction, or by himself and assistants, in connections
with the geological surveys of Mississippi and Louisiana,
as well as the Tenth Census of the United States, by Drs.
Eugene A. Smith and R. H. Loughridge; the chemical work for
the Pacific Northwest, under the auspices of the Northern
Transcontinental Survey, by M. E. Jaffa and Geo. E. Colby;
that in California, at the Experiment Station, by the
latter two, Dr. R. H. Loughridge, and temporary assistants.
It would be impossible to segregate, without excessive
prolixity, the credit to be assigned to each of these
participants.]
A.
Adametz, L., 142, 281.
Agassiz, L., 4.
Aso, K., 383.
B.
Bamber, —, 401, 410, 414.
Batholomew, J. G. 294.
Beyerinck, M. W., 151, 156.
Blumtritt, E., 276.
Bonnier, G., 521.
Böttcher, O., 393.
Boussingault, J. B., 151, 276, 313.
Brick, —, 528.
Brock, see Morck, D.
Burri, R., 148.
Butler, O., 151.
C.
Cameron, F. K., 380, 466, 532, 533.
Clarke, F. W., XXIV, 23.
Colby, G. E., note above.
Colmore, C. A., 448.
Contejean, Ch., 521, 523, 531.
Coville, F. V., 536.
Crochetelle, J., 146, 147.
D.
Darton, N. H., 10.
Darwin, Ch., 158.
Davy, J. B., 535.
Deherain, P. P., 146, 147.
Detmer, W., 127.
Djemil, —, 159.
Duclaux, P. E., 144.
Duggar, J. F., 155.
Dumont, J., 146, 147.
Dyer, B., 339, 357.
E.
Ebermayer, E., 279, 305.
Eckart, C. F., 212.
Eichorn, —, 327.
Ermann, G. A., 303.
F.
Fawcett, W., 355.
Fischer, Hugo, 156.
Fliche, P., 520, 521.
Forbes, R. H., 219.
Fortier, S., 194, 254.
Fraenkel, L., 142.
Frank, A., 151.
Fuelles, P., 281.
Furry, F. E., 73.
Furuta, T., 383.
G.
Geikie, J., 14.
Gerlach, —, 156.
Gilbert, G. K., 2.
Gilbert, J. H., 151, 192.
Godlewski, E., 337, 393
Goss, A., 376, 530.
Grandeau, L., 132, 133, 139, 357, 520, 521.
H.
Haberlandt, F., 310.
Hall, A. D., 210, 227.
Hare, R. F., 378.
Harper, R. M., 494.
Hartwell, B. L., 123.
Headden, H. P., 18.
Hedin, Sven, 9.
Hellriegel, F., 130, 151, 192.
Henrici, 200.
Hillman, F. H., 536.
Hiltner, L., 154.
Hoffmann, R., 528.
Hohl, J., 143.
Hunt, T. S., 23.
J.
Jaffa, M. E., 135, 381, 450, 530.
Johnson, S. W., 60, 380.
K.
Katayama, T., 383.
Kearney, T. H., 532.
Kedzie, R. C., 343, 375.
Kellner, O., 393.
King, F. H., 99, 108, 109, 168, 192, 193, 210, 211, 212, 224,
228, 236, 305, 325, 328, 332.
Kinsley, J. S., 143.
Knop, W., 197.
Koch, R., 156, 281.
Kossovitch, P., 363.
Kosticheff, P., 130, 157.
Kröber, 156.
Krocker, F., 22.
Kuntze, O., 67, 68.
L.
Ladd, E. F., 131, 133, 134, 141.
Langley, S. P., 288.
Lawes, J., 151, 192.
Lea, E. C., 387.
Leather, J. W., 401, 410, 411, 412, 414 to 417, 440.
Lemberg, J., 272
Lesage, M., 528.
Letheby, H., 23.
Liebig, J. von, 150, 313.
Liebscher, G., 354.
Lipman, J. G., 156.
Loeb, J., 380.
Loew, O., 23, 42, 382, 383.
Loughridge, R. H., 87, 207, 213, 214, 240, 259, 340 to 342,
385, 430, 462, 466, 513, 535, 560.
M.
Maercker, M., 65, 369.
Mann, H. H., 401, 410, 413.
Manson, M., 294.
Maxwell, W., 339.
May, D. W., 42, 380.
Mayer, A., 199, 207, 209.
Mayo, N. S., 143.
Mazurenko, D. P., 87.
Means, T. H., 248, 478.
Merrill, G. P., 2, 13, 167.
Middendorff, V., 441.
Mitscherlich, E. A., 99, 199.
Miquel, P., 142, 281, 359.
Mohr, Chas., 489, 511.
Moore, G. T., 154.
Morck, D., 154.
Müller, A., 449.
Müller, P. E., 122, 184.
Müntz, A., 142, 355, 370, 401, 402, 406 to 410.
Murray, John, 23, 24.
Myers, H. C., 6, 144.
N.
Naegeli, C. v., 129.
Nagaoka, M., 65, 393.
Nobbe, F., 154.
O.
Osterhout, W. J. V., 533.
Ototzky, L., 265.
Owen, D. D., 316, 317, 343, 513.
P.
Peter, A. M., 175.
Peter, R., 316,317, 343.
Pichard, P., 147.
Porter, J. L., 23, 24.
Pumpelly, R., 110.
R.
Rafter, G. W., 217.
[204]Ramann, E.
Reade, T. M., 41.
Regnault, V., 26.
Reichert, E., 276.
Richthofen, F. von, 110.
Risler, E., 354.
Rosenberg, S., 528.
Rousseaux, E., 355, 370, 401, 402, 406 to 410.
Rudzinski, D., 87.
Russell, I. C., 24.
S.
Saussure, H. E. de, 150.
Schimper, A. F. W., 523, 528.
Schloesing, Th., 59, 111, 354.
Schloesing, Th., fils, 332, 393.
Schmidt, C., 23.
Schöne, H. E., 90.
Schübler, J. J., 116, 197, 313.
Schultze, H., 328, 329.
Seton, E. T., 159, 160.
Shaler, N. S., 12.
Shaw, G. W., 465.
Smith, E. A., 511.
Snyder, H., 131, 133, 134, 139.
Stenhouse, —, 276.
Stockbridge, H. E., 307, 308.
Stone, C. H. H., 25.
Stubenrauch, A. V., 222.
Stutzer, A., 149.
T.
Thurmann, J., 519, 520.
Tolman, L. M., 387.
Tourney, J. W., 216.
Traphagen, F. W., 23.
Tuxen, C. F. A., 184.
U.
Udden, J. A., 106.
Ulbricht, R., 328.
V.
Vanderyst, H., 338.
Ville, G., 151.
Voelcker, J. A., 22, 410.
Vogel, J. H., 156.
W.
Wagner, P., 65.
Ward, M., 144.
Warington, R., 108, 146.
Washington, H. S., xxiv.
Way, J. T., 22, 73.
Weber, A. H., 450.
Wheeler, H. J., 123.
Whitney, M., 94, 195, 207, 316, 321, 330, 332, 337.
Wilfarth, H., 151.
Williams, W. E., 60, 100.
Winogradsky, S., 146, 156.
Wohltmann, F., 355, 370, 401, 402 to 405, 406, 416.
Wolff, E., 22, 73.
Wollny, E., 110, 113, 125, 147, 159, 195, 264, 279,
281, 284, 305, 306.
Wüllner, —, 198.
Wunder, G., 327.
Y.
Yoder, P. A., 92.
Z.
Zöller, P. H., 22.
[204] This writer’s valuable “Boden Runde” (1905) unfortunately came to
hand too late to be considered in this volume.
Printed in the United States of America.