S621

•Z4

1913

Zerban, P V

The salt marshes of the north
coast of Porto Rico

BULLETIN No. 4. April, 191:3.

(English Edition.)

EXPERIMENT STATION
of the

SUGAR PRODUCERS' ASSOCIATION OF

PORTO RICO.

RIO PIEDRAS, P. R.

The Salt Marshes of the North Coast of Porto Rico,

By F. W. Zerban.

THE TIMES PUBLISHING Co.
1913.

SUGAR PRODUCERS' ASSOC \TION OF PORTO RICO.

LIBRARY

THE NEW YORK BOTANICAL U .
BRONX, NEW YORK 1045J

OFFICERS.

Kamon Aboy Benitez .... President

Antonio S. Alcaide ... Vice-President

Agustin Navarrete Secretary

DIRECTORS.

A. J. Greif T. G. I. Waymouth

Jorge Bird Arias L. H. Farnum

Eduardo Giorgetti Lucas P. Valdivieso

Kafael Fabian Arturo Quintero

Luis Kubert

EXPERIMENT STATION STAr F.

J. T. Crawley Director

D. L. Van Dine Entomologist

J. R. Johnston Pathologist

* W. B. Cady Chemist

H. B. Cowgill Assistant Pathologist

T. H. Jones Assistant Entomologist

M. Cabrera Stenographer & Translator

* F. W. Zerban, former chemist, resigned January 1, 1913.

NEW YOl

BOTANIC.
GARDE*

PREFACE

Iii this publication are presented the results of an investigation
which was proposed by Mr. Crawley, Director of this Station, and the
writer wishes to express his thanks to him for many valuable sugges-
tions made during the progress of the work.

As probably some of the readers for whom this bulletin is prim-
arily i nl ended may not be familiar with chemistry, the author has en-
deavored to use chemical terms as little as possible. But the very
nature of the subject is such that they cannot be entirely avoided; and
for the benefit of those who have only a slight knowledge of such terms,
a few explanations may not be out of place. Most agricultural workers
nowadays know what is meant by those terms which designate the dif-
ferenl chemical substances that form the important parts of soils, such
as lime, nitrogen, phosphoric acid and potash. But they may not be
so well acquainted with some words from the7 chemical vocabulary which
the writer has had to make use of in this publication. It would ob-
viously be out of place here to attempt giving a detailed account of all
these terms, and strict scientific accuracy will have to be sacrificed to
brevity and conciseness.

By the term "salt" which is so much used in this bulletin, the
chemist designates a substance which may be considered as consisting
of two components in a very firm combination. One of these compo-
nents is usually some metal, as for instance sodium, potassium, calcium,
magnesium, iron, aluminium, etc., and the other component is either a
non-metalic element, as for instance chlorine, or a combination of such
p non-metalic element with the element oxygen. The metals which are
the elements characteristic of basic substances, like caustic soda or quick
lime, are in this bulletin termed "basic radicles", and the other radicles
which are characteristic of acids like carbonic, sulfuric, hydrochloric,
etc.. are called "acid radicles". The combinations of basic and acid
radicles are called salts, like sodium sulfate, calcium chloride, etc. One
acid and one base may forjn several salts by combining in different well
defined proportions. Thus sodium bicarbonate contains only one car-
bonic acid radicle for one of sodium, whereas sodium carbonate has one
for two of sodium. In chemical analysis it is necessary to
"determine the acid radicles by themselves and the basic radicles
by themselves, and their sum total gives the total quantity
of salts present, which may exist there in a number of

combinations. Thus, if we find in a given salt solution, sodium and
potassium on the one hand, and sulfuric and hydrocholorie acids on the
othe'r, we would have in the solution the four salts: sodium chloride,
sodium sulfate, potassium chloride and potassium sulfate, in certain
proportions.

In our analyses we give only the different radicles found without
paying attention to their possible combinations which do not concern us
much. These few words on the subject win probably suffice to give la
those readers who are not familiar with chemistry, the necessary ex-
planations.

The writer is indebted, besides Mr. Crawley, to the following
gentlemen who have rendered him assistance in this investigation; Mr.
J. C. Howells, Irrigation Engineer; Mr. J. R. Johnston, Pathologist of
this Station; Mr. E. E. Olding, formely manager of Central Cambala-
che; Mr. H. Shapley, Chemist of Central Plazuela ; Mr. W. E. Hess, of
the Agricultural Experiment Station at Mayaguez; Mr. Santiago Sifre,
Administrator of Central Plazuela ; and Mr. Justiniano Santiago, Admi-
nistrator of the Tiburones lands, managed by the Plazuela Sugar Com-
pany. The writer wishes to express his thanks to all these gentlemen,
whose help is greatly appreciated by him.

rii

Fable of. Contents.

Page.

Introduction 6

Character of soil, and its bearing on possible methods

of amelioration 8

The salt content of the marsh soils, and its relation to

the production of cane 14

A. Cano de Tiburones

First series of analyses 21

Second series of analyses 3 1

Third series of analyses 37

B. Other marshes 39

reclamation of the marshes ....... 40

THE SALT MARSHES ON THE NORTH COAST OF PORTO RICO

INTRODUCTION.

With the ever increasing population in nearly all parts of the globe
the demand for food stuffs is constantly rising and even the adoption
of more intensive methods of cultivation has not been able to keep pace
with it. Consequently, large stretches of land, which had formerly been
thought to be unfit for the production of crops, have in recent times been
taken into cultivation. Immense areas of slight rainfall in the western
United States have been reclaimed for agricultural purposes, simply by
providing them with drainage and irrigation. In northern Europe people
found themselves obliged long ago to utilize marsh and moor lands
which presented the most difficult problems in their reclamation. In
Late years attention has been called to lands of a similar nature in the
United States, especially in Wisconsin, Indiana, and in the Atlantic and
Gulf States. It is true that in some of these cases, as for instance in
Connecticut and New Jersey, the principal reason for the drying of these
marsh areas was the fact that millions of mosquitoes annually breed in
them, rendering all the surrounding country uninhabitable ; but even
there the gain in arable land is no small item.

The island of Porto Rico has, in proportion to its size, a considerable
area of swamp and marsh lands. The good land which may be used
profitably for the growing of sugar cane is practically all under
cultivation now; prices of land are constantly rising, and thus the
question has recently arisen as to whether the extended marshes, commonly
called "poyales", which are found along the coast, may be made to
produce cane at a profit, A beginning at reclamation has already been
made in one of these marshes, and the studies reported on in this bulletin,
have mainly been upon that particular marsh.

There are several swamp areas of considerable extent on the north
coast, and the one just mentioned is the largest of them all. It extends
from the vicinity of Arecibo to the west to within a small distance of
Barceloneta to the east, and is usually called the "Carlo de Tiburones"
or "Laguna de Tiburones". The other marsh areas are from west to

C3.ST !

Acreage

1) Laguna de Tortuguero and surrounding marshes, acrea-
ge unknown. ....

2) Marshlands controlled by the San Vicente Sugar Com-
pany

3) Palmas— Cienagade la Mar, mangrove landsand marshes 705 acres

4) Pueblo Viejo Abajo — Marsh lands bordering on the Bay
of San Juan and the San Fernando Canal to the north:
on Finca Canejas to the south: on Ensenadade la Crio-
11a, Rio Puerto Nuevo and Quebrada Margarita to the
east; and on the San Fernando Canal to the west;
acreage unknown. ....

5) Mangrove lands of Ensenada de Pueblo Viejo and Mar-
tin Pefia Canal 726 "

6) Hoyo Mulas— Mangroveland on the westside of the La-

guna de Mata Redonda, or Torrecilla 111 "

7) Mangrove lands of the Laguna San Jose, as far as the

city limit of San Juan 127 :i

8) Mangiove lands of Boca Cangrejos 125 "

9) Cangrejos Arriba — Mangrove lands of the Laguna Ma-
ta Redonda and the San Jose Canal 356 "

10) Mangrove lands of the Laguna Pifiones and the Hoyo

Mulas Canal . 898 "

11) Mangrove lands of the Laguna Mata Redonda or To-
rrecilla, Hoyo Mulas and Cangrejos canal 1252 ••

12) Barrio Cabezas— Mangrove lands and marshes 150 ''

The foregoing list was furnished by the Department of the Interior
of the Insular Government, and comprises the mangrove lands and
marshes belonging to the People of Porto Rico, ami situated along Lie
north coast of the island, according to the data found in the archives of the
Department. Only the lands under No. 2 were added to this list by the
writer, they having passed into private ownership.

All these marsh and swamp lands are located only a short distance
from the sea shore and separated from it usually by low sand bars or
coral reefs. Some of them are still, directly or indirectly, connected
with the sea, while others are completely isolated. In their natural state
they are either covered with water or the ground water is quite near
the surface. %

The native vegetation of these marshes consists mainly of the
following plants, which Mr. J. R. Johnston, Pathologist of this Station
and Mr. W. E. Hess, of the Agricultural Experiment Station at Maya-
giiez, have identified. In the Caho de Tiburones there were found,
Melanthera aspera — Compositae ; Andropogon sp. — Gramineae ; Cono-
carpus erectus — Combretaceae ; Lippia nodinora — Verbenaceae ; Polygala
panniculata— Polygalaceae : Hydrocotyle sp. — Umbelliferae ; and one of
the Cyperaceae (Johnston.) In the vicinity of the Laguna de San Jose
the vegetation consisted of mangrove, polypodium and typical salt land
■.edges and rushes, (Hess).

8

CHARACTER OF SOIL, AND ITS BEARING ON POSSIBLE

METHODS OF AMELIORATION.

The soils of these marshes are of a very peculiar nature, and it was
with the object of learning something definite about their physical and
chemical characteristics, that the present investigation was undertaken;
the ultimate object being, of course, to obtain data as to the best methods
of improving them and of increasing their crop-producing power. The
soil consists of two principal strata. The upper layer is a grayish black
to black mass, formed of the debris of decaying vegetable matter. In
some places the forms of decayed roots and other plant parts may be
seen with the naked eye; in others a more complete decomposition has
taken place and the soil presents the appearance of a fine humous mass.
It is very porous and when partly dry feels quite elastic when stepped
upon . Its depth in most places is at least several feet; only in a few
locations is it as little as four inches. The amount of moisture in the
soils in their natural state is exceedingly high, as is to be expected under
the circumstances. The average moisture of 23 samples was found to
be 83%, with a minimum of 77% and a maximum of 91%. The vegetable
origin of the soil is evident from its appearance and from its chemical
composition. The agricultural analyses of six samples, by the methods
of the Association of Official Agricultural Chemists, gave the following
figures :

TABLE I.

(1) (2) (3) (4)

Moisture, in fresh state 88.869!

Moisture, air dry 17.82

Insoluble residue .71

Volatile matter 87.06

Oxide of iron and alumina 1.61

Lime 5.58

Magnesia 1.70

Potash 0.09

Phosphoric acid 0.05

Calcium carbonate 3.45%

Lime, not in form of carbonate, . 3.65

Total nitrogen 2 09

Humus 34.38

Humus nitrogen .91

% of humus 2.65

(5)

Moisture, in fresh state 82.41%

air dry 12.96

Insoluble residue 16.16

Volatile matter 60.85

Oxide of iron and alumina 9.38

Lime, 11.22

Magnesia 0.52

Potash 0.23

Phosphoric acid 0.13

Calcium carbonate 12.55%

Lime not in form of carbonate. . 3.19

Total nitrogen 1.63

Humus , 25.42

Humus nitrogen 1.00

% of humus 3.93

These samples came from the following locations':

No. 1 Caiio de Tiburones, Colonia A, Pieza 1, to 12 in. depth.

No. 2 San Vicente, Guarico, Surface soil.

No. 3 Tortuguero, Surface soil.

No. 4 Carlo de Tiburones, Cambalaehe property, Pieza 2, to 2ft
depth.

No. 5 Cano de Tiburones, Cambalaehe property, Pieza 4, to 2ft.
depth.

No. 6 Cano de Tiburones, Cambalaehe property, Pieza 5, to 2ft.
depth.

The average moisture content of the six samples in their natural

77.01%

91.20%

78.66%

17.23

11.78

16.56

8.94

21.06

3.75

81.64

56.96

81.88

4.39

4.53

2.65

3.30

12 63

8.53

0.65

0.59

0.85

0.20

0.21

0.21

0.05

0.06

0.24

2.65'

7.78%

1.82

4.18

1.92

2.82

37.82

30.73

1.82

1.65

4.81

5.38

(6)

Average

85.01%

83.86%

15.37

15.79

4.53

9.69

77.05

72.57

4.69

4.54

10.63

8.65

0.51

0.80

0.25

0.20

0.11

0.11

12.58%

7.80%

2.59

3.09

2.69

2.27

30. 79

31.83

1.75

1.43

5.68

4.49

10

state is almost 84%, and even when air dry they still retain 15.79% of
moisture j it is quite probable though that part of this loss of weight on
drying is due to decomposition of the organic matter. Almost three
fourths (72.57%) of the perfectly dry substance volatilizes upon igni-
tion. Most of this volatile matter is of an organic nature, since the
loss due to the presence of hydrated silicates, oxide of iron and alumina,
and that due to carbon dioxide, cannot be very high. Thus the soils
are by their chemical analysis also characterized as of vegetable origin.
No. 1 is typical of these soils. The residue insoluble in hydrochloric acid
amounts to less than 1%, and the rest of the inorganic material is
principally calcium and magnesium carbonate. The soils are well provided
with carbonate of lime and the quantity of magnesia is quite small as
compared with that of lime. As regards the other plant food ingredients,
we find the percentage, of potash and of phosphoric acid to be rather
small, while the nitrogen is exceedingly high. This we would naturally
expect to be the case in a soil of this character. However, the actual
percentages calculated on the perfectly dry soils would be entirely
misleading, should we base any conclusions on them regarding their crop
producing power, hi the tropics, 0.2% of potash and 0.1% of phosphoric
acid would, in an otherwise good mineral soil, be considered quite
sufficient. But if we calculate the actual quantity of plant food per
acre foot of this vegetable soil, we find that the quantities of potash
and phosphoric acid arc exceedingly small, as may be seen from the
following consideration. The volume weight of the soil, i. e., the weight
per unit volume in its natural state, in five samples, was found to be
1.06 on the average, therefore the weight per acre foot amounts to a
little less than 3,000,000 pounds. Since 100 parts of soil contain only
16.14 parts of solid material, the total weight of solid material per acre
foot is roughly 500.000 pounds. One tenth of one per cent of this is
equal to 500 pounds, and we thus find that the soil contains on an
average only 500 pounds of phosphoric acid and 1,000 pounds of potash
per acre foot, and all of this is probably not immediately available for
the crop. The nitrogen, however, amounts to 11,000 pounds per acre foot,
and 7,000 pounds of this are found in the humus matter alone. According
to Hilgard. the uitrogen that is not found existing in the humus, is of
practically no value to growing crops, only the humus nitrogen being
used in nitrification. Hilgard also maintains that the percentage of
nitrogen in the humus should not be below 4' /', , as otherwise the soil may
become "nitrogen hungry". Whether this is true in the case of these
soils, remains to he seen; at all events the average percentage of nitrogen
in the humus is above 1', . and moreover, the actual quantity of humus
nitrogen per acre fool in our soil is higher than in 63 out of 72 soils
quoted hy Hilgard.

11

The subsoil of this marsh is a white or yellow mass of loamy con-
sistency, and has the following composition :

TABLE II

(1) (2) (3) (4)

Moisture, in fresh state 58.80% 55.73 42.21 66.38

Moisture, air dry 2.69 1.88 2.62 3.72

Insoluble residue U.33 0.27 1.88 0.26

Carbon dioxide 41.78 39.41 38.19 37.0i

Volatile matter not carbon I g 3g Q() 1Q4& t 3

dioxide )

Oxide of iron and alumina 0.85 0.61 1.26 0.14

Lime 51.22 4b. 41 45.50 44.14

Magnesia 1.40 1.25 2.22 2.1-2

Potash 0.07 U.07 0.06 0.0<o

Phosphoiic acid 0.03 0.01 0.02 0.02

Total nitrogen 0.19 0.50 0.66 0.48

Humus 1.52 1.32 2.24 2.56

Humus nitrogen 0.10 0.12 0.23 0.08

» % of humus. 6.49 9.19 10.25 7.22

The samples were collected in the following places:

No. 1 Cano de Tiburones, Colonia A, Pieza 3, 4 to 12 in.

No. 2 San Vicente, Guarico, Subsoil.

No. 3 Caho de Tiburones, Colonia A, Pieza 1, second foot.

No. 4 Caho de Tiburones, Colonia A, Pieza 3, second foot.

It appears from the analyses that this subsoil is a limestone, more
or less mixed with organic material. The moisture is quite high in
these samples in their fresh state, but they retain very little of it after
drying. The principal constituent is calcium carbonate with a small
amount of magnesium carbonate. The insoluble residue, the oxide of
iron and alumina, are insignificant, and the volatile matter is
practically all of an organic nature, with the exception of the carbon
dioxide in combination with lime and magnesia. Where the organic matter
rises to from 9 to 15%, the nitrogen is accordingly higher than in No. 1,
where the respective figures are only 3.38% of organic matter and .19%
of nitrogen. Potash and phosphoric acid are extremely low. It will
not be necessary to discuss at length the agricultural conditions of this
subsoil except in so far as it exerts an influence on the surface stratum,
for the simple reason that in most places the black layer is so thick that
the cane roots do not come in contact with the lime subsoil. The interest-
ing point in the composition of this subsoil is the fact that its calcareous
nature explains the high percentage of calcium carbonate in the black
soil, and the non-acidity of the same. If the subsoil consisted of material
devoid of calcium carbonate, the black soil would certainly be highly
acid, and any attempt at reclamation would be practically prohibitive or

12

at least very expensive. Where the lime appears near the surface there
is some danger of having too much lime present for the growing of cane.
But this difficulty could be overcome by incorporating with it some of
the black vegetable mould and thus reducing the danger arising from an
excess of lime. Such a mixing has been partially effected in Colonia A,
Field No. I ; here the lime is near the surface, and the material resulting
from the digging of the ditches was thrown on top of the black soil and
mixed with it. The composition of the soil formed in this way was the
following :

Moisture, in fresh state 62.20%

Moisture, air dry 6.70%

Insoluble residue ... 2.61%

Volatile matter 60.58%

Oxide of iron and alumina ... 1.19%

Lime 33.02%

Magnesia 1.98%

Potash 0.10%

Phosphoric acid ... 0.07%

Total Nitrogen 1.91%

Humus 12.06%

Humus nitrogen 0.78%

Humus nitrogen c/c of humus 6.43%

This is substantially the composition that we would expect to find
in a mixture of the black soil and of the marl.

From the general character of these soils we might conclude that
they should after reclamation, and with judicious fertilization and
cultural methods be able to produce good crops. Unfortunately there is
too little known about tropical soils of this character, to make any offhand
recomendations in that direction. British Guiana has large stretches of
peaty soils, but there the layer of peat is, according to Noel Deerr, not
very thick, and the subsoil consists of a gray clay, poor in lime and with
an excess of magnesia over lime. It seems that so far there has been
very little need in the tropics of utilizing marsh lands for the cultivation
of dry land crops. Most of the experience gained on marsh soils has
been gathered in the temperate zone, and we cannot directly apply the
results obtained there to our case. A large part of the marsh soils in
northern lOurope and in the United States is of an acid character, and
in their reclamation it is necessary to apply liberal quantities of lime,
usually in the form ot: carbonate, with three purposes in view. In the
first place, the calcium carbonate neutralizes the free acids present in
the soil; second, it causes ;i rapid decomposition of the partly deca.yed
plant remnants, thus bringing about rapid huinification ; and in the third
place, it favors the growth of nitrifying organisms and makes the
nitrogen available which would otherwise be inert.

13

In a number of places the marsh soils themselves contain sufficient
lime to render a further addition of this substance unnecessary. Such
is the case in some marsh soils in northern Europe, in Ontario, in certain
areas in Wisconsin, and as we have already seen, in the majority of the
marsh soils of Porto Rico. Extensive studies of marsh soils have been
made by the University of Wisconsin and the most important conclusions
that were arrived are as follows (1) :

" Through proper drainage and soil management much of this land can
by made very productive and will add greatly to the farm area of the state.
The chemical composition and the possibility of thorough drainage are the
chief factors which determine the value of marsh lands for cultivation. The
drainage of marshes is the first step toward improvement. On large marshes
the organization of drainage districts and the cooperation of a number of
adjoining land owners is necessary, but thousands of farms include some land
which can be readily drained by the owners without legal difficulties. Pro-
per tillage of marsh lands is of the utmost importance. Heavy rolling by
packing the loose peat soil, produces a firmer seed bed which is better
adapted to cultvated crops, especially small grains. Fertilization of the
marsh soils is important on account of the unbalanced condition of the ele-
ments which they contain. Marsh soils are excessively rich in nitrogen,
but are frequently deficient in phosphorus and potash While barn yard
manure will supply the last two elements, these can be supplied in com-
mercial fertililizers. allowing the use of barn yard manure on upland soils
where its nitrogen as well as its mineral elements are needed Under
such special conditions it is profitable to use commercial fertilizers supple-
menting the manure of the farm. The crops best adapted to marsh lands
nclude corn "

Some of the results of special experimo?its in the non-acid marshes of
Wisconsin may be of interest in this connection. It was found that :

" Owing to'the presence of lime carbonate and hence to the «sweet» cha
racter of these soils, there is no dificulty in securing the necessary decom-
position of the soil to supply an abundance of nitrogen where ^ood drainage
is developed. As a rule, the amount of nitrogen in these soils is so large
that it is unnecessary to use fertilizers that contain this element so
that barn yard manure, the most important element of which is nitrogen
may be used on upland soils which require it, using only mineral fertilizers
on the marsh soils as needed.

There seem to be two effects of the presence of lime carbonate on the
phosphorus supply of these marsh soils; first that it carries with it a some-
what larger amount of phosphorus than is found in other marsh soils,
and even more important than this, seems to render what is there more
available than it is in acid marsh soils. Tn Wisconsin so far as these marsh
soils in the southeastern part of the state have been cropped they have not
shown a special need for phosphate fertilizers. However, it is quite pro-
bable that after some years of cropping they will be found to need some
supply of phosphorus, as do all other soils.

The only marked need for special treatment which the marsh soils of
this portion of the state, when properly drained ordinarily show within
the first few years after reclamation, is for potash. Quite frequently these
marshes when planted to corn or other crop, show patches of from a few
rods to several acres in extent on which the seed germinates well, but the
crop turns yellow at an early stajre and fails to develop. It frequently
happens that corn will grow to a height of only one or two feet during
the whole season and produce no grain whatever. Where this occurs, so far
as our experience goes, it is due either to the lack of sufficient drainage
or the lack of a supply of available potash. For some reason not yet fully
understood, the potash present in the soil is not available and some fertili-
zer must be used.

(1) Wisconsin Agric. Expt. Sta.. Bull. 205. pp. 2 and 16 to 17; 1911.

14

In many cases experiments during the past ten years, on soils of diffe-
rent character in this portion of the state, have shown increases in yield
all the way from two to five or six times, by the application of potash fer-
tilizers only. "

To what extent these conclusions will hold true in the case of the
Porto Rican marshes, remains to be seen. They give, however, some ind-
ications as to what field experiments are apt to give good results. The
first and paramount necessity in the reclamation of all marsh lands,
is sufficient drainage, and this is especially so in the marsh soils of Porto
Rico. The reasons for this latter statement will be fully explained in the
following chapters of this bulletin. As far as fertilization goes, we may
expect, on the basis of the studies reported and of the analyses of the
Porto Rican marsh soils made in this laboratory, that they will be
benefitted by the application of potash and phosphoric fertilizers, but
that nitrogen may not have much effect, owing to its presence in large
amounts in the 'soils themselves. It is, however, possible that the humus
nitrogen may not be so available as it has been found to be in other
countries. The only way to decide the question of fertilizer requirements
is by actual experiments in the field where the three elements are applied
alone or in mixtures of various proportions, in different forms, and in
varying: quantities. Only such a practical test will disclose what fertilizers
wall bring the greatest pecuniary profits.

The administrator who was in charge of the Tiburones lands last
year, made a small test with potassium sulfate alone, applying it in some
of the worst lands. The cane soon improved visibly, and the result of
this small test demonstrates the value of such experiments. However.
in order to get results of permanent value, il will be neeessarv to n
the experiments in a systematic way so that tbe influences of other fac-
tors than fertilizers may be excluded as much as is practicable.

THE SALT CONTENT OF THE MARSH SOILS,
AND ITS RELATION TO THE PRODUCTION <>F CANE.

In an ordinary marsh, drainage is provided with the main object
of removing the surplus water, and of reducing the moisture to such an
extent that the physical, chemical, and biological processes, without which
the soil cannot support the growth of cultivated plants, may take place
normally. But in two other large classes of soils, namely, the marine saline
lands, and the alkali lands, the establishment of a good drainage system
is necessary for another most important reason. While these two soil
groups show certain differences in their nature and origin, the soluble
salts which arc characteristic of both, are qualitatively identical, and the
object of reclamation is essentially the same in both eases. The dominanl
feature of these soils is the comparatively high quantity of soluble salts

15

found in them. The most common of these salts is sodium chloride, but
besides this we may find, and often do find, the chlorides of calcium, potas-
sium and magnesium, and the sulfates, bicarbonates and carbonates of
these four metals. AVe hardly ever find only one salt present in any one
soil, but usually most or all of them in varying proportions.

Most cultivated plants are unable to grow in soils that are heavily
charged with salts. The injury produced is due to direct as well as
indirect causes. There is a direct corrosive action on the roots; and
there are also produced, through the salts that are taken up by the plant,
certain disturbances of the natural biological processes. Among the
indirect effects of alkali one of the most important probably is that on
nitrificalioji. Lipman (*) has found that nitrification does not proceed
normally when the concentration of sodium carbonate in the soil reach.es
0.025%. Sodium chloride is less toxic, and nitrification is quite normal
up to a concentration of 0.1 r; of this salt, while the quantity of sodium
sulfate may reach even 0.35% without ill effects. The effect of salts
on a rnmonifieation is of a different order, sodium chloride being the
most toxic and sodium carbonate the least. These results are most
important and they may partly explain the favorable effect of lime
salts in salt lands. They counteract the influence of the other salts with
the result that nitrification may proceed normally, which it could not
do in the presence of the other salts by themselves.

If it is intended to use salt lands for agricultural purposes, the salts
must be partly or wholly removed. In some cases certain measures will
produce a considerable improvement, for instance the application of
calcium sulfate which counteracts the effects of other salts and converts
sodium carbonate into the less toxic sulfate, under the formation, at the
same time, of insoluble calcium carbonate. But such measures as these
will be effective in rare cases only. There is only one method which will
absolutely and permanently reclaim the better of these lands, and this is
an efficient system of drainage in connection with irrigation to leach out
the salts.

There exist great differences in the tolerance of plants for different
salts, and in that of different plants for the same salt. The limits of salt
content also vary with the character of the soil. In general it may be
said that sodium carbonate is the most toxic of all salts; the upper
limit tolerated, for instance, by cereals in a sandy loam soil, is about
0.1 % ; sodium chloride, sodium bicarbonate and magnesium chloride are
less toxic, and the maximum for sodium chloride is, under the above
conditions, 0.25%. Sodium sulfate and magnesium sulfate are still less
harmful than the former, the limit of sodium sulfate being about 0.45
to 0.5% (1). Calcium salts are the least toxic of all and rather large

(1) Centr. Bakt. Parasitenk.. IT. Abt., Vol. 33, pp. 305-313.
~W Hilgard, "Soils", p. 464.

16

quantities of these salts are readily tolerated. For other plants and in
other soils these figures may vary to a greater or less extent.

The conditions are much more complicated where we find mixtures
of the different salts in the »drae soil. If the effect of the different
salts were simply additive, then we could easily calculate what their
total effect would be. But the effect of one salt not only does not
intensify the action of others, but en the contrary there are certain salts
which will counteract the effect of others. Thus sulfates in general will
mitigate the effects of carbonates, bicarbonates and chlorides, and calcium
salts in general will counteract sodium and magnesium salts. For this
reason it is sometimes very difficult to interpret the results of analyses
of soluble salts contained in a given soil.

While some plants are quite resistant to the effect of soluble salts,
others are easily harmed by even small amounts. There are certain grasses
and other plants that grow well only in places highly impregnated with
salt, But they are very few. Among cultivated plants, beets, barley and
asparagus are most resistant. Another important point is, that plants
usually are much less resistant when young than after they have fully
developed and are naturally stronger. Thus the salt content of a soil
may, during the growth of a plant decidedly increase, without detriment
to the plant, and finally reach a concentration which would have killed
the plant in the earlier stages of its growth. A good example of this
behavior is alfalfa which shows little resistance to salts when young, but
wbicb will stand enormous amounts in subsequent years without showing
signs of injury.

Tbe character of the soil is also very important in this connection.
In stiff soils the tolerance for salts is usually much less than in light
soils which can be more easily cultivated, thus helping the plant in its
attempt to resisl the effeet of the salts. Tn soils high in carbonate of lime
the different salts are less injurious than in those devoid of lime, because,
as we have already seen, lime salts counteract the effect of sodium and
magnesium salts. A high nitrogen content in soils is also helpful against
the bad effect of salts in the soil.

Having thus reviewed the effects of salts in soils in a general way
we sliall now turn to the sugar cane in particular which is the natural
crop for the coast lands of Porlo Rico. As the cane is not grown for its
total weight but for the sugar contained in it. we have to make a distinc-
tion between tbe influence of salts on the growth of the cane and that of
its composition.

There is an apparent difference of opinion among authors concern-
ing the effect of salt on the srrowth of the cane. Some say that cane will
thrive on soils impregnated with salt (1). Tn Jamaica, Barbados, Trinidad

(1) Journal d' Agriculture Tropicale, Vol. 1. p. 145.

17

and Demerara it has been found that an occasional flooding with sea water
or the application of sodium chloride in certain fields is quite beneficial.
This fact is explained by Prinsen Geerligs (1) on the ground that a
treatment with sodium chloride renders the potash, lime and magnesia
contained in the soil more available, as was proven by experiments made
by himself and also by studies made, independently, by Eckart (2). It
is also a well known fact of plant and animal physiology that certain
substances when applied in large doses, are toxic to plants and animals,
but have, when used in small quantities, quite the opposite effect and
rather act as stimulants. While it is thus true that sodium chloride in
small quantities may be quite beneficial in soils with low chlorine content
and with small percentages of available potash and lime, it is equally
true that there is a certain limit above which sodium chloride becomes
detrimental to the growth of cane. On the basis of many analyses
Maxwell arrived at the conclusion that in ordinary soils percentages of
sodium chloride exceeding 0.15% (0.09% of chlorine) will prevent the
normal growth of cane (3). In soils which are w7ell provided with nitrogen
the chlorine content may go higher than 0.15% of sodium chloride without
causing any harm. If the chlorine is combined mainly with calcium it
may also reach higher figures than 0.09%. Eckart concludes from the
analyses of several Hawaiian soils that "where the salt content of the
soil reaches over 0.1% (0.06% of chlorine) an injurious effect is produced
on the cane." (4). Figures on the tolerance of cane for other salts, like
sulfates, carbonates and bicarbonates are still lacking and carefully
controlled experiments will have to be made to find out how much of the
different salts, by themselves and in mixtures, the cane will stand without
harmful effects. In the meantime we shall have to content ourselves with
observations made with soils and canes in the field. A beginning in this
direction has already been made at this Station and these studies are
being continued. From the results obtained so far it seems that the limit
of endurance for sodium chloride in our mineral soils is about the
same as that found by Maxwell and Eckart in Hawaii ; but it also appears
that cane in its later stages of growth may stand much higher quantities
cf salt without visible injury.

It has been said above that not only the growth of the cane is
affected by the presence of salts but that its composition is also largely
influenced by it, This is well shown by the results of field experiments
made at the Experiment Station of the Hawaiian Sugar Planters' As-
sociation. A comparison of two plots, one of them irrigated with
fresh water and the other with salt water containing 200 grains of salt

[1J Intern. Sugar Journal, 1905.

[2] Expt. Sta. of Hawaiian Sugar Planters' Assn., Eeport for 1902.

[3] Office of Expt. Stations, Bull 90, p. 17.

[4] Expt. Sta. of Hawaiian Sugar Planters' Assn. Special Bull. B, p. 51.

18
per U. S. gallon (3428 parts per million), gave the following results (1)

TABLE III.

N«?

Quality
of water

Brix

Sucrose

Glucose

Purity

Salt,
grs per
gallon.

Tons
cane.

Sucrose

in

cane.

Sugar
per acre,
Tons

1

2

Fresh
Salt

20.3

15.9

18.9 0.31
13.8 0.28

93.2

86.8

16.17
173.67

76
15

16.9
12.35

12.8
1.86

Similar results were obtained in comparing two plats which received
an occasional heavy irrigation, as may be seen from table IV I1).

TABLE IV.

N9

Quality
of water

Brix

Sucrose

Glucose

Pin ity

Salt,
grs per
gallon

14.24

180.6

Tons
cane

Sucrose

in

cane

16.7

12.5

.Sugar

per acre

Tons

3
4

Fresh
Salt

20.0
16.1

18.7
14.0

0.29
0.27

93.4

87.1

91.5
31.25

15.3
3.9

It appears from these two tables that salt accumulated in the soil,
besides preventing the normal growth of the cane, also affects its composi-
tion in a most deleterious manner.

It was further shown in the experiments just mentioned that lime
applied to soil which is impregnated with salt will help much toward
saving the crop; while the growth of the cane is still greatly impeded,
its composition becomes normal. The application of nitrogen in the
form of dried blood had the same effect as lime.

Some analyses made in this laboratory also tend to show that a high
salt content in the soil depresses the sucrose content and purity of the
juice in the cane. The analyses of the respective soils and canes follow :

[11 Expt, Sta. of H. S. P. A., Bulletin 11.

19
TABLE V.

Series I. Central "Mercedita".

Carbonic acid, (Co 3)

Bicarbonic acid, as(HCO 3) 2

Chlorine

Sulfuric acid, as SO 4

Calcium

Magnesium

Potassium

Sodium

Soil N<? 1.

Soil N<? 2

.007%

.006%

.101

.110

.125

.015

.082

.036

059

.041

.006

.004

.007

.005

.080

.015

.467%

.232%

Variety.

Number of stalks

Weight per stalk in pounds

Extraction

Brix

Sucrose

Glucose

Purity

Glucose Ratio

Non Sugars

Non Sugar Ratio

Potassium Chloride .

Potassium Sulfate

Pottassium Chloride plus Sulfate

Cane N«? 1.

Cane N<? 2

Blanca

Blanca

2.

2.

3.1

2.8

60.6

59.3

19.3

21.0

15.5

18.3

2.5

1.3

80.3

87.1

16.1

7.1

1.3

1.4

8.4

7.7

0.331%

0.138%

0.109%

0.135%

0.440%

0.273%

20
Series II, Central

Carbonic acido as, (Co 3) ... .
Bicarbonic acid as, (HCO 3)2

Chlorine

Sulfuric acid as, (SO 4)

Calcium . .

Magnesium

Potassium

Sodium

ral "Cortada."

Soil TsTo 1.

Soil N° 2

.002%

.006%

.087

.055

.114

.006

.033

.005

.011

()16

.005

.004

•.005

.004

.099

.004

.356%

.103%

Cane N<? 1.

Variety Cristalina

Number of stalks 5.

Weight per stalk in pounds 2.1

Extraction 45.9

Brix 17.9

Sucrose 13.7

Glucose 2.1

Purity 76.5

Glucose Ratio 15.3

Non-Sugars 2.1

Non-Sugar Ratio 15.3

Potassium Chloride 0.337%

Potassium Sulfate 0 075%

Potassium Chloride plus Sulfate . . . »>.412%

Maxwell gives some further figures (*) on the influence of the salt
content of the soil on the yield of sugar. They show clearly that the sugar
production decreases with a rising salt content of the soil:

Cane N<? 2

Cristalina

5.

2 2

42.9

18.3

15.3

1.5

83.6

9 8

1 5

9.8

0.312%

0.091%

0.403%

TABLE VI

A.

Salt in watei

Salt in cane
juice

Condition
of cane

.125%
.223%

.470%
.714%

Growing
Dying

Condition of
irrigation watesr

Slightly brackish
Highly brackish

B.

Pa t f field. Salt in soil </0. Yield of sugar per acre. Tons.

6.0
1.5
0.0

(1) "Office of Experiment Stations, Bui. 90, p. 17."

1

0.10

2

0.45

3

1.00

21

The actual factory yield is even smaller than would appear from
the sucrose content and purity of the juices, because cane from salt land
contains more chlorine than that from soil free from chlorides (See
tables III to VI), and it is a well known fact that a high salt content
in the cane depresses the quantity of available sugar and causes an
increase in the amount of molasses obtained.

CANO DE T1BURONES

FIRST SERIES OF ANALYSES.

After the brief review of the literature on the effect of salts upon the
growth and composition of the cane, given in the preceding chapters, we
shall now take up the specific problem of the marsh soils on the north
coast of tnis island. As iias been remarked above, the Cano de Tiburones
was choswn for these studies because it is the largest of these marsh
areas, being fairly representative of all of them, and also because the
work of reclamation w as already in active progress when this investigation
was begun, thus requiring immediate attention. Two large canals had
already been dug ; one on the north side near the edge of the swamp and
running about parallel with its longer axis, and another parallel to the
first, but along the south side of the swamp, and toward the hills. Both
canals unite at a place some distance from the outlet into the Arecibo
River and discharge their drainage waters into this river near its mouth.

In order to get a general idea of the conditions in the whole district,
as far as the salt content of the soils and its influence on the cane is
concerned, a number of soil samples (8) were taken by Mr. Ho wells,
engineer in charge of irrigation investigations of the Plazuela Sugar
Company by which corporation these estates are managed; and at the
same time the cane growing in the same places was examined by Mr. J.
R.Johnston, Pathologist of this Station. Some more samples were collected
by the writer, and these, in combination with those taken by Mr. Howells,
comprise pretty well all the soil types of the estate, including the best
luam lands down to the marsh itself. The results of this first investigation,
which were partly incorporated in a report made jointly by Mr. Johnston
and the writer, are discussed on pages 21-31 of this bulletin.

At many places on the estate a white incrustation may be seen on
the surface of the soil which is evidently formed by evaporation of the
soil solution. A sample of such an incrustation adhering to the soil was
taken in the low lands of "Paja", and analysed with the following
results. The air dry substance contained per cent:

22

Carbonic acid, as (Co 3) 0.000%

Bicarbonic acid, as (HCO 3)2 0.164%

Chlorine 1.162%

Sulfuric acid (80 4) 0.119%

Calcium , 0.090%

Magnesium 0.031%

Potassium 0.058%

Sodium 0.683%

2.307%

The percentage composition of the incrustation as calculated from
this analysis, is as follows:

/

Carbonic acid as (CO 3) 0.00%

Bicarbonic acid (HCO 3)2 7.08%

Chlorine 50.36%

Sulfuric acid (SO 4) 5.17%

Calcium 3.90%

Magnesium 1.37%

Potassium r 2.51%

Sodium 29.59%

100.00%

It is readily seen that the main constituent of this incrustation,
commonly called "potasa" in that neighborhood, is sodium chloride,
which is mixed with small amounts of the bicarbonates and sulfates of
calcium, magnesium and potassium.

Knowing the nature of the incrustation, it was desirable to find out,
in what quantities the salts found were present in the different parts
of the estate, and whether they are present to such an extent as to
influence the cane as regards growth, diseases and insects.

Mr. Howells collected at each place a sample of the soil itself, and
besides a subsoil sample at the depth of five feet. Notes were taken on
the yield of the cane, the level of the ground water, the number of years
during which the field had been under cultivation, and on the use of
fertilizers. Mr. Shapley, Chemist of Plazuela, kindly furnished us with
analyses of the ground water at the different places wher<*
the samples were taken. The first of these was collected at the part
of the estate which is situated towards the Caiio de Tiburones, about
2800 meters west of the central factory, and the other samples at about
equidistant points in the direction towards the Central, that is east, and
then from there, at a right angle, going south, towards the hills. Table
VII gives the definite locations where the samples were collected, and
the other data obtained with the exception of the analyses of the gound
water which are given in table IX, (page 26).

23

TABLA VII.

Distance

Water level

Yield of cane

in tons

Time

Time ferti-

No

from Central

below

1910

in cane,

lizer have

meters

surface.

Plant cane

Crop

years

6

been used

1

2800, W.

1.5 ft.

22.80

2

2200, W.

2.0 fck

37.10

23.25(3)

40 to 50

3

1600, W.

3.0 "

53.15

27.75^)

40 to 50

4

050, W-

3.0 "

21.30

—

40 to 50

5 years

5

0

4.0 "

42.25

27.00(0

40 to 50

5 kk

6

700, S.

9.0 •'

22.00

15.00(2>

40 to 50

5 "

7

1500, S.

12.0 "

37.00

29.80^)

40 to 50

—

8

2400, 8.

14.0 "

—

— —

30

—

Note

(1)

Second ratoon.

(2)

Third

(3)

Fifth

On examiation of the general condition of the cane and of the
amount of infestation by diseases and insects, Mr. Johnston reported the
following facts:

No. 1. Very small amount of root disease and very few insects. No
root grubs. A good root system developed, but many of the roots dead.

No. 2. Good deal of root fungus. Roots well developed. Root hairs
in pretty good shape. Cane about fair.

No. 3. Much root fungus. Root system only fair, root hairs in poor
condition; many dead and dry shoots, probably due to soil conditions.

No. 4. Worse than No. 3. Great deal of root disease. Well developed
root system, but many dead roots. Root hairs scarce.

No. 5. Some root disease. Root system fairly good, plenty of root
hairs.

No. 6. Very small amount of root disease. Very good root system
and root hairs.

No. 7. No signs of root disease. Roots and root hairs in excellent
condition.

No. 8. Some root fungus. But roots well developed and root hairs
in good condition.

The condition of the root system is considered of more importance
than the presence or absence of root fungi or insects. The abundance of
root hairs in good condition determines the ability of the plant to
assimilate sufficient water for its needs.

The other samples mentioned on page 21, and taken by the writer,
comprised the following :

No. 9. In Colonia A, field No. 1; about 12000 meters from the
central factory; the soils from this place are typical marsh soils and
their agricultural analyses have been given in the preceding chapter.
The first of the 3 samples represents the surface stratum, about four
inches thick, and consists of a mixture of the black vegetable mould and

21

the white marl. Its agricultural analysis is given on page (12). The next
sample is the black vegetable mould itself, found in the same place, from
four to twelve inches depth ; it is the soil whose analysis is found on page
(9), table I, under No. 1. The ground water in this place is about 18
inches below the surface. The last of the three samples is the white
marl, the agricultural analysis of which may be seen on page (11), table
II, un.ier No. 3.

The cane in this field absolutely refused to grow in some places, and
in others the little cane there was, showed a very stunted growth and a
yelJowish appearance.

No. 10. is situated in "Paja", tablon 3, about 2500 meters from the
factory. The cane at this place was not very vigorous, yielding only about
20 tons per acre; it was evidently suffering, in spite of the fine
composition of the soil itself which has 1.51% of lime, 0.42% of potash,
0.17% of phosphoric acid and 0.38% of nitrogen. The surface soil was
six inches deep, and the subsoil was sampled to the depth of eighteen
inches.

No. 11 is the Experimental Field near the factory between the two
places where samples Nos. 5 & 6 were collected. The cane is quite healthy
here, but the yields are not very good. The soil was sampled to the
depth of twelve inches, the subsoil from twelve to twenty four inches.

All the soil samples described were, in the fresh state, analysed
for moisture, carbonates, bicarbonates, chlorides and sulfates, and the
results .are given in table VIII. None of the samples showed any alkaline
carbonates; but they have a slight alkalinity due to the presence of
bicarbonates which are, in a strictly chemical sense, acid salts, however
salts of a very strong base and a \^ry weak acid, so that the character of
the former predominates.

25

TABLE VIII.

Water soluble constituents in Plazuela soils, on moisture free basis,

in per cent.

SERIE I.

Bicarbonates.

Clorine

Sulfates

(HCO 3) 2

CI 2

SO 4

N°

1

Soil

.149

.137

.015

N°

1

Subsoil

.215

.180

.033

N°

2

Soil

.084

.043

.014

NP

2

Subsoil

.090

.354

.035

N<?

3

Soil

.077

.114

.007

N°

3

Subsoil

.098

.126

.020

N°

4

Soil

.069

.119

.009

n°

4

Subsoil

.040

.111

.010

n°

5

Soil

.049

.026

.011

n°

5

Subsoil

.042

.125

.015

N°

6

Soil

.065

.014

Trace

N<?

6

Subsoil

.026

.021

Trace

N°

7

Soil

.021

.016

Trace

N°

7

Subsoil

.032

.013

Trace

N°

8

Soil

.022

.011

Trace

N°

8

Subsoil

.020

.013

Trace

N°

9

Soil, 0 to

4 in. .318

.186

.138

N<?

9

" 4 to

12 " .199

1.674

.462

N°

9

Subsoil

.211

.248

.149

N°

10

Soil

.097

.164

.042

N9

10

Subsoil

.090

.212

.047

N°

11

Soil

.022

.017

.032

N°

11

Subsoil

.032

.029

.030

26

The following table, No. IX, gives the composition of the water in
the drainage ditches, sampled near the places where the soil samples were
taken.

TABLE IX.

Parts per mil Ion

w

Total Solids

Chlorine

Sulfates, SO 3

1

1040.8

380

51.1

2

1804.0

727

68.3

3

2162.0

740

205.7

4

1740.0

610

trace

5

2180.0

758

163.0

6

440.0

70

25.2

7

320.0

28

trace

8

238.0

25

trace

9

2193.2

835.0

187.8

10

2353.6

1010

107.1

Branch of Canal I
near N? 1

1040.8

340

68.3

North

Can

a 1,1

2100.0

880

172.1

near cen

North
last bri

Canal,
dge

-,

909.6

745

126.0

Mouth

of Canals J

near A

recibo Ri-

2644.0

1085

171.6

ver

(At location No. 11 a sample of the drainage water could not be ta
ken, as the ditches were dry.)

All these analyses, with the exception of Nos. 9 and 10, were made
by Mr. Shapley, Chemist at Plazuela.

We have seen before that when a given sample of soil contains not
one but several salts simultaneously, the injurious action of these salts' is
not directly additive. On the contrary, any salt when present in a soil
in mixture with other salts, is less harmful than would be the case were
it present by itself. However, when the salts contained in several samples
are present in about the same proportions in each one, then the total
quantity of salts found in each sample will be representative of the
relative amount of injury caused by the salts in that sample. Such is
the case in our soils, and therefore, in discussing the results of our
analyses, we shall consider the sum of the acid radicles, as given in the
above tables. The higher we find the total quantity of salts, the more
injury we may expect.

We shall first try to determine if there is any regularity in the
general distribution of the salts over the estates controlled by the Plazuela
Sugar Company. With this purpose in view we shall arrange in tabular
form the average figures for the total acid radicles of each soil and its
corresponding subsoil, as being indicative of the "saltness" of the place,

27

TABLE X

Location

Distance from

Factory.

9

12,000

m.

w.

1

2800

i k

b t

10

2500

it

t t

2

2200

k

t t

3

1600

tt

t t

4

650

k

tt

5

0

11

300

m

s.

6

700

it

1 1

7

1500

tt

i t

8

2400

1 1

tt

i.e. of the total amount of salts present, in the order of the different
locations, beginning at the marsh and going in the direction to the
factory, and from there towards the mountains. These figures are
compiled in table X.

Total acid radicales

1.190%
.365
.326
.311
.222
.179
.134
.081
.063
.041
.032

(It must be remarked here, that there is a fresh water spring near
location 1, which dilutes the soil solution, as may also be seen from the
analysis of the drainage water at this particular point (See page 26).
The normal salt content would therefore be much larger than is indicated
by the figure in the above table.)

It is readily seen that the total amount of salts gradually dimin-
ishes in the direction from the marsh to the factory and from there to
the hills. There is quite a drop from the marsh soil to the first mineral
soil, but from there on the differences are more regular.

If we now ask what relation exists between the salt content of the
soil and the condition of the cane as regards root system, diseases and
insects, we cannot base any conclusions solely on the figures given in
table X, but we must consider that the cane is a shallow feeder, the roots
being comparatively short, Therefore, we must in this discussion pay
particular attention to the surface soil in which the cane actually grows.
For this reason we have compiled, in table XI, the figures for total acid
radicles, and also for chlorine alone, present in the surface soils, again in
the same sequence as in table X.

28
TABLE XI.

Location Total acid radicles Chlorine

9 J. 771% 1.178%

1 .301 .137

10 .326 .188

2 .142 .043

3 .198 .114

4 .198 .119

5 .085 .026

11 .071 .017

6 .079 .014

7 .037 .016

8 .033 .011

We find that here the figures for total acid radicles are not as regular
as in table X, but these discrepancies are only apparent, and, in fact,
help to explain the condition of the came from the respective places.

In the discussion which follows we shall take up each location
separately , and study the relation between the salt content of the soil and
the condition of the cane. The dscription of the condition of the cane in
the different places is due to Mr. Johnston.

9. — In this location cane had been planted for the first time, and it
was either dead or dying. There is no doubt that the high percentage
of salts was iaigely responsible for this (1.178% of chlorine and 1.111%
of total acid radicles.)

1. — Here the plant crop for 1910 produced only 27.8 tons per acre,
notwithstanding the land had been in cultivation only 6 years. Fertilizer
had never been applied. In the adjacent field of old cane there was a
small amount of root disease, and very few insects. Some stools showed
absolutely no root disease, while in others it was confined entirely to a
few small dead shoots. The root system was well developed but many of
the roots were dead indicating either injurious parasites or a bad
condition of t he soil as to constitution or texture. Parasites were not
present in sufficient amount to account for any injury to the cane. It
must be noted here that the soil was comparatively shallow and that the
subsoil with its high chlorine content of 0.18% came in contact with the
lower part of the root system. As the amount of the salts present
increases and decreases at any given point according to the rise and
fall of the water level it will be readily seen how a good root system
may have developed but subsequently bcame injured. The soil was ap-
parently rich in plant food but of rather close consistency. Altogether the
physical condition of the soil may have had a small part in preventing
e, big crop of cane, but the matter of fungus or insect enemies may be
entirely eliminated, leaving the majority of the blame to the salt content
which amounted to a total of .301% acid radicles, .137% being chlorine.

29

It has been stated on page (27) that the salt content at this pk*~e
would be higher if there were not a fresh water spring right near. It is
for this reason that the chlorine and also the total acid radicles are lower
here than at the next location, 10, while we would expect the opposite to
be the case. But even with only 0.137%of chlorine and 0.301% of total
acid radicles the cane would probably have suffered more, were it not for
the high nitrogen content of this soil, which tends to neutralize the
injurious effects of the salts.

10. — Here the yield was also small, about 20 tons per acre. There
was a considerable amount of small cane found, and it did not have a
normal appearance. The trouble is evidently due to the high salt content
(.326% total acid radicles, and .188% chlorine), and would certainly
have been more pronounced yet, if the soil did not, like at 1, contain a
large percentage of nitrogen (0.38%), and, besides, 1.5% of lime.

2. — About this station the land had been in cultivation for from
40 to 50 years. The crop of 1910 produced only 22.8 tons for the fifth
ratoon while the first crop of the same planting produced 37.1 tons. The
root system of the cane was in good condition, well developed with plenty

of good root hairs, notwithstanding a large amount of root fungus
present, The texture of the soil at this station was loose, and consequently

the drainage good. The soil was dark, and apparently rich in plant food.
There was nothing in the texture of the soil to warrant the presence of
so much root fungus. Probably the cane was weakened from some other
cause and thus allowed the fungus free play on the cane, for it seems to
be a fact that the root fungus on vigorous cane does little damage, while
on weak cane it seriously accentuates the trouble.

The salt content in this soil was found exceptionally low, for this
particular place, only .142% of total acid radicles, and but .043% of
chlorine, when we should expect a much higher figure. But this is easily
explained. This soil is very porous, and the subsoil begins at a much
lower level than in sample 1. Otherwise the soils and subsoils of the
two places are very similar. This place, 2, evidently had a good rain
shortly before the samples were taken, as may be seen from the figures
for moisture in the fresh samples, 46% and 70% respectively. The
result naturally is that the salt which might have accumulated in the
soil was washed down into the subsoil Avhere it actually appears in a
concentration of 0.35% of chlorine, but out of reach of the bulk of the
roots of the cane.

3. — This section has been in cane for from 40 to 50 years. No
fertilizer had ever been used here. The tonnage shows a rather remark-
able decrease from 53.1 tons of the plant crop to 27.7 tons for the fifth
ratoon cut in 1910. The cane shows much root fungus together with a
root system in very poor condition, a large number of roots being dead.
The soil is a heavy clay and apparently not very rich. The chlorine

30

content of this soil is .114%, the total acid radicles amounting to .198%.

4. — in cultivation for 40 to 50 years with fertilizer used during
5 years. The plant crop cut in 1910 amounted to only 21.3 tons. There
was much root disease and the roots were in very poor shape. The soil
was a very heavy clay. The chlorine content here was .119% (.198% total
acid radicles), a little higher than in 3. Both of these soils are stiff
clays, very different in structure from 1, 10 and 2, which are open dark
soils rich in humus.

5. — Here we enter a region where the chlorine content of the soil
is getting slight, even though there be still quite a quantity of it present
in the subsoil. This area, 5, had been in cultivation also for 40 to 50
years, and fertilizer had been used for five years. The tonnage of the
plant crop was 42.25 tons while that of the second ratoon of the same
planting was 27.00 tons. There was some root disease but the root system
was in good condition. The chlorine content of the soil was only 0.026%
(total acid radicles 0.085%), much less than at No. 4. The soil is a
rather heavy clay.

11 and 6. — These two locations do not materially differ from each
other. The land here had been in cultivation for 40 to 50 years, and had
been fertilized for five years. The plant crop from No. 6 gave only 22
tons, and the third ratoon cut in 1910 gave but 15 tons. The cane showed
a very small amount of root disease and a good root system. The chlorine
in the soil was only 0.014 to 0.017% (total acid radicles 0.071 to 0.079%.)
Evidently the chlorine cannot, in Ihis case, be made responsible for the
small production, but some other factor, possibly lack of fertility, must
be the cause of it.

7. — In cultivation for 40 to 50 years, but no fertilizer used. The plant
crop gave 37 tons, but the second ratoon crop in 1910 gave only 29.8
There was no root disease present and the root system was in excellent
condition. The chlorine was low, 0.016%, the total acid radicles 0.037%.

8. — This area had been in cultivation for about 30 years and no
fertilizer had ever been used. It is said to produce 60 tons of cane, but
actual records are not available. Some root fungus was found, but the
root system Avas good. The chlorine here was only 0.011% (total acid
radicles 0.033%).

Tf we now compare all of the results obtained we see at once that
there exists a very striking relation between the salt content of the
soils and the general condition of the cane grown in them. Taking a
vigorous, healthy root system as the predominating factor in determining
the condition of the cane, we find that where the chlorine content is found
to be from 0.014 to 0.043%, and the total acid radicles from 0.033 to
0.142%. the cane is in good condition, and where the chlorine is above
0.114% (total acid radicles above 0.198%), the cane is not normal. There
was no salt content found between 0.142 and 0.198% of total acid radicles,

31

and between 0.043 and 0.114% of chlorine, so that we cannot say where
the exact limit lies, above which the cane will be injured by chlorides and
other salts. But it is somewhere between the figures just given. It is
possible that all the figures for chlorine, etc., were a little higher than
the average for a growing season, as the samples were taken at the end
of a dry spell. Heavy rains would have reduced the salt to some extent,
at least for a time.

While it is evident that the general condition of the cane is greatly
influenced by the salt content of the soil, there is no direct relation
between this latter and the actual amount of disease present. In places
where the salt content is very lowT, considerable root disease may be
present, and in others, where the salt is high, root disease may not be
found. This fact is strikingly shown at location No. 1, where the
conditions of moisture etc. seem to be excellent for the development of the
root fungus. But it is more than probable that the salt content of that
soil is too high for the proper development of the fungus.

From the first series of analyses reported on in the preceding pages
we may conclude that in the ordinary mineral soils of the region investi-
gated the danger point for chlorine is between 0.043 and 0.114% (0.142
and 0.198% of total acid radicles), and that it is probably quite near that
fixed for Hawaiian conditions by Maxwell at 0.09% (0.15% of sodium
chloride), and by Eckart at 0.06^ chlorine (0.1% of sodium chloride).

SECOND SERIES OF ANALYSES.

Having thus made a general survey of the conditions obtaining on
the estates controlled by the Plazuela Sugar Company, so far as the
salt content of the soils is concerned, and having established the limit
of chlorine that the cane will stand in the ordinary soil types, attention
was now centered on the marsh itself. The general working plan was the
same as in the first investigation: a number of locations were carefully
selected, soil samples taken and the condition of the cane noted at the
same time. The area studied in this second investigation lies along a
branch of the plantation railroad which runs across the Caho de Tiburo-
nes at a point between kilometers 12 and 13 of the main line of the same
railroad, from north to south, crossing both drainage canals. This part
of the estate had only recently been planted to cane for the first time
(Spring 1911 ; samples taken in June 1911). Samples of soil were taken
at five different points along the branch line, collecting separately ths
samples of the surface foot and that of the underlying second foot. At the
same time notes were taken on the condition of the cane and on the height
of the water level at each place, during high tide.

All of the soil in this entire field is the very moist black vegetable
mould already fully described. The' exact depth of this material was not
ascertained, but the underlying stratum most probably consists of the

32

same white marl which crops out at the surface in Colonia A, at the edge
cf the swamp and at some distance from the field under investigation.
The agricultural analyses of these soils have been given on previous pages
of this bulletin. We have seen that the black material is very rich in
humus, and that even the marl underneath to the depth of two two feet
is well supplied with it. In accordance with this the nitrogen content of
the black material is very high, exceeding two per cent of the dry soil,
decreasing in the lower layers. The subsoil consists of almost pure calcium
carbonate, and even the black material contains on the average 8.65% of
lime. The magnesia is .8% in the soil and 1.75% in the subsoil. Potash
and phosphoric acid are low, .2 and .1% respectively in the soil, and .065
and .02% in the subsoil.

If we now compare the nature of the injurious soil constituents
existing in the first series of soils with that of those contained in this
series, we find some very remarkable and important differences.
Generally speaking, the soils used in the first investigation are very
different in character from those which we are to discuss now. All samples
but one of the first series were collected within a radius of 2,800 meters
from the central factory and represented regular mineral soil types. In
the present series, however, we have to deal with vegetable moulds, formed
in a medium impregnated with salts. In the first as well as in the second
area we find white incrustations on the surface of the land, but in their
composition the incrustations from the two places are entirely different.
In the first area the crust was found to consist mainly of sodium chloride,
with small amounts of the sulfates and bicarbonates of calcium
magnesium and potassium. The incrustation that is found in enormous
quantities in the swamp area of the Cano de Tiburones, on the other
hand, is for the most part insoluble in water and consists principally of
calcium carbonate. The water soluble part of this incrustation amounts
to less than one half per cent of the total, and is made up of about equal
parts of bicarbonates, chlorides and sulfates. The analyses of this
incrustation follow here :

COMPLETE ANALYSIS

Moisture 2.50%

Insoluble i esidue 0.78%

Carbon dioxide and volatile matter 45.79%

Iron oxide and alumina 0.94%

Lime 48.37%

Magnesia 1.23%

Potash .... 0.04%

Soda 0.18%

99.83%

33

WATER SOLUBLE CONSTITUENTS.

Carbonates 0.000%

Bicarbonates, (HCO 3) 2 0.112 "

Chlorine, CI 2 0.084"

Sulfates, (SO 4) 0.114"

The formation of this incrustation is easily explained. As the soil
contains a large percentage of calcium carbonate, considerable quantities
are dissolved during wet weather, by the combined action of water and
of the carbon dioxide dissolved in it. In dry weather this solution cf
calcium bicarbonate rises to the surface and dries up, losing a part of it>s
carbonic acid, and being redeposited as normal calcium carbonate.
Naturally, chlorides and sulfates are mixed with it, having risen to the
surface through the same forces as the calcium bicarbonate.

It is important to note that in the incrustation of the first type, the
sulfuric acid radicle, S04, amounts to less than 9% of the total water
soluble acid radicles, whereas in that of the second type its quantity is
37% of the total. Again, in the different soil samples of the first series,
the same relation ranges from 6 to 9%, and in those of the second from
21 to as much as 78%, as Ave shall see from the analyses given further
on.

Having pointed out these important differences in the characteristics
of the areas investigated, we shall now examine in detail the results of
the study of the Tiburones swamp lands.

As before, we shall again give the results of the field investigations
in tabular form. We have stated above that the samples were taken along
a cross section of the swamp, at a right angle with its longitudinal axis,
beginning at the north border of the swamp and proceeding south to
its south border. Towards the two sides the land is higher than towards
the center of the marsh, as may be judged from the water levels given in
table XII. Column 1 of this indicates the distance of each location from
the edge of the field lying next to the north border of the swamp ; column
2 gives the height of the water level, and column 3 the condition of the
cane growing at the point where the sample was taken.

34

TABLE XII.
NO 1 2 3

Distance from Water level Condition of cane, and remarks

North end

1 57 meters 2.5 ft. Good cane, dark green foliage; 7

monts old, 6 ft. high.

2 410 " 2.0 ft. Medium fair cane, not as gren as

N° 1; leaves at base dried up: 5 mo.
old, 4.5 ft. high.

3 783 " 15 in- Weak, sickly cane, leaves yellow; 3

to 4 mo. old, 18 in. high; surface
incrustation.

4 1025 " 15 in. Cane dying; leaves yelow; 3 to 4 mo.

old, 15 in. high; surface incrustation.

5 1410 " 18 in. Better cane, leaves green; 5 mo old

2.5 to 3 feet high.
In table XIII are given the results of the analyses of the two samples,
representing the first and scond foot respectively, of each location.
The average figures for the entire depth of two feet are also given, as in
this loose soil the roots of the cane will penetrate beyond the first foot. The
first column of table XIII indicates bicarbonates calculated as bicarbonie
acid ion, (HC03) 2, as has been done before; column 2 gives the chlorine
(C12), the third the sulfuric acid ion (S04), the fourth the sum total of
acid radicles, and the fifth the sum of bicarbonie acid and chlorine. The
reason for this arrangement will soon be apparent.

TABLE XIII.
WATER SOLUBLE CONSTITUENTS IN TIBURONES SOILS,
ON MOISTURE FREE BASIS, IN .%;

SERIES II.
(HC03)2 CI 2 SO 4 Total (HC0 3)2

Acid Rad. +C1 2

N«? 1 1 foot .088 .112 .980 1.179 .200

„ „ 2 feet .080 .189 .658 .927 .269

Average

W 2, 1 foot
,, ,, 2 feet

Average

N<? 3, 1 foot
., ,, 2 feet

Average

N<? 4, 1 foot
„ 2, 2 feet

Average

P 5, 1 foot

, , , , Z toot

Average .234 .059 .082 .375 .293

Note: — None of the samples contained normal carbonates.

.084

.150

.819

1.063

.234

.121
.134

.244

.400

.511

.844

.876
1.379

.365
.534

.128

.322

.678

1.127

.450

.587
.211

.054
.157

.347
.150

.988/

.518

.641

.367

.399

.105

.249

.753

.504

.472
.512

.125
.213

.198
.161

.794
.886

.597
.725

.492

.169

.179

.840

.661

.309
.159

.060
.057

.116
.047

.486
.264

.369
.216

35

In discussing the analytical results of the first series of soil samples,
the amount of injury to the cane to be expected could be estimated on
the basis of the total amount of salts present, chlorine and bicarbonates
being the chief factors, since sulfates were found in small quantities only,
from 6 to 9% of the total. This manner of interpretation could be used
there, since, as stated before, the salts contained in the several samples
were present in about the same proportion in each. If in the present
series of analyses we should consider the total amount of salts to be
indicative of the injury to be expected, we would arrive at entirely
erroneous conclusions. In such a case No. 2 would be expected to grow
the worst cane, following nos. 1, 4, 3, and 5. The facts show that such is
not the case. Nor can the chlorine content alone be used as a criterion.
Sample No. 3 had .1% of chlorine, and the cane was dying; No. 1 had
.15% of chlorine, and the cane there was vigorous and healthy.

A further examination of the table shows that the proportion of
bicarbonate to chlorine and to sulfate in any one sample is quite different
from that in the other samples so that we cannot draw conclusions in
the same way as we did in the first series of analyses.

How are we then to interpret the figures of the table? Returning
again to what was said in the discussion of the first series of analyses,
chlorides and bicarbonates are about equally injurious while sulfates are
much less so. In fact, sulfates are not only less injurious, but, in mixtures
with other salts, even exert a protective effect, so that the other salts in
the presence of sulfates are less injurious. A good illustration of this
phenomenon is afforded by a case cited by Hilgard, concerning the
growth of sugar beets in salt land ( Hilgard 's "Soils", page 466) : Beets
were "good" where the sulfate (Glauber's salt) ranged up to 0.8%, with
.1 to .2% of common salt; but so soon as the latter rose above .2%, the
beets were poor despite the low percentage of Glauber's salt ; then became
"good" again so soon as the common salt fell below 0.2%, although the
Glauber's salt increased. Investigations by Cameron have also shown
that sulfates, and more especially calcium sulfate counteract the injurious
effect of sodium and other soluble salts. As in the soils under investiga-
tion lime is present in considerable quantities, the sulfuric acid found in
the samples must first be combined with lime, forming calcium sulfate.
We shall see how markedly the protective influence of calcium sulfate is
shown in our samples.

Beginning with No. 1, we found a vigorous, healthy cane with a
dark green foliage which in seven months had attained a height of six
feet. The average sum of chlorine and bicarbonic acid is lower than in
any other sample, viz. .234%, and the sulfuric acid, representing the
protective influence, is highest, .819%.

At the next station the sum of bicarbonic acid and chlorine has
reached .45% and the sulfuric acid is slightly lower than in the first,
.678%. Corespondingly the cane was not as good as in No. 1. The leaves

36

were still green, and the cane had made a good growth in five months,
attaining a height of four and a half feet, but the basal leaves were
somewhat burned, thus exhibiting the injurious action of the salts
present.

At location No. 3 the cane was weak and sickly looking, the leaves
being yellow and drying up. The total height of the cane after three to
four months growth was only 18 inches. We are therefore not surprised
to find .504% of bicarbonic acid and chlorine, with .641% in the first foot
alone; while the sulfuric acid radicle amounts to only .249%, which is not
more than one half of the other radicles, while in Nos. 1 and 2 the sulfuric
acid radicles was largely in excess.

Location No. 4 presented about the same appearance as the foregoing ;
the cane was possibly somewhat worse than at No. 3, having grown to oniy
15 inches in three months and being gractically in a dying condition.
Correspondingly we find here the highest quantity of bicarbonic acid and
chlorine, viz. .661%, with .597% in the first foot; and at the same time
the sulfuric acid is quite low, only .179%.

No. 5 had better cane. This had grown to a height of 2.5 to 3 feet
m three months, and looked much healthier then than the cane at locations
3 and 4. In accordance with these findings we have much less bicarbonic
acid and chlorine, only .293%. From this we might expect even better
cane than at station No. 2, but there we have a large quantity of sulfate
present, whereas in No. 5 it amounts to only .082%.

There is another factor yet which must be considered in the inter-
pretation of the results, namely the height of the water level. In a large
part of the field the ground water comes quite near to the roots of the
cane, and the water alone will damage the cane, even if it be not salty.

While the condition of the cane at the different stations can easily
be accounted for relatively, by the proportions of the salts present, the
absolute amount of chlorine and of bicarbonic acid that will permit the
cane to grow, is much higher than that found in the mineral soils discus-
sed before. We find that the cane at this place will grow well where the
chlorine content is .15%, the sum of bicarbonic acid and chlorine
amounting to .234% ; and that it even grows comparatively well at a place
where the chlorine is as high as .322%, and the sum of this and of
bicarbonic acid .45%. In the other area we had found the limit of chlor-
ine that the cane will endure 1o be between 0.04 and 0.11%. In the
present case there are evidently several factors at work which raise the
endurance limit of the cane towards salts beyond the point we had found
before. These factors have already been discussed at length, and we shall
only briefly recapitulate them here. The first of them is the protective
influence of sulfates against the injurious effects of other salts. The
second is the fact that calcium salts in general, and especially the sulfate,
are not only less harmful by themselves, but act as antidotes to the salts

37

of sodium and magnesium. The third reason why the cane will at this
place stand more salt than at others, is the high nitrogen content of the

black vegetable mould.

THIRD SERIES OF ANALYSES.

In order to get more data on the subject which might enable us to
fix numerically the limit of tolerance for salts in these marsh lands,
another series of samples was taken in the Cane de Tiburones, in April
1912. The area investigated at this time was situated in that part of the
marsh which is controlled by Central Cambalache. It is located in the
south-west quarter of the marsh, near the railroad station Santana. Here
cane had been planted one season before, and the crop had been cut and
allowed to ratoon wherever the condition of the cane warranted this
policy. In other parts it had been left standing without cutting.

Sample No. 1 was taken in field No. 2. The cane here was ratoon cane,
quite vigorous and healthy, and had attained a height of from seven to
eight feet.

No. 2 came from field No. 4, also in ratoon cane. The cane here was
apparently healthy, but it was not as good as in location No. 1, having
grown to a height of only five feet.

At location No. 3, also in field 4, the cane had likewise been cut
and allowed to ratoon. But it was only about three feet high and showed
marked signs of suffering.

In place No. 4, located in field No. 8, the cane, when first planted,
bad germinated, but most of it subsequently died.

In location No. 5, in field 5, the cane did not even germinate.

It is important to note here that in locations No. 1, 2 and 3 the
ground water was low enough to be out of reach of the cane roots, whereas
in Nos. 4 and 5 it was quite near the surface.

Table No. XIV gives the analyses of the soils from the 5 places, to
the depth of two feet.

38

TABLE XIV.

WATER SOLUBLE CONSTITUENTS IN TIBURONES SOILS,
ON MOISTURE FREE BASIS, IN %

SERIE III.

12 3 4 5

(HCO 3) 2 .284 .417 .465 .430 .566

CI 2 .124 .126 .125 .199 .297

So 4 .237 .204 .278 .201 .358

Total acid ra-
dicles

i

.645

.747

.868

.830

1.221

Calcium
Magnesium
Alkali (Sodium)

1

.153
.035

.058

.172
.042

.057

.190
.048
.080

.140
.043
.145

.247
.057
.186

Total basic ra-
dicles

.246

.271

.318

.328

.490

Acid radicles
Basic radicales

.645
.246

.747
.271

.868
.318

.830
.328

1.221

.490

Total Salts .891 1.018 1.186 1/158 1.710

(HCO 3) 2+CI 2 .408 .543 .590 .628 .862

SO 4 .237 .204 .278 .201 .358

It appears from (he analyses lliat the conditions in this area of the
marsh are less complicated than in the second series reported on before,
inasmuch as the proportion of the sulfates to the sum of bicarbonates and
chlorides is more uniform than it was there. While in the second series
the quantity of sulfates, expressed in per cent of the sum of bicarbonates
and chlorides, ranged from 28% to 356 %, it varies here only between
31% and 59'/ . The amount of sulfates is throughout much smaller than
that of the sum of bicarbonates and chlorides, and the influence of the
sulfates is not only slight, but also about proportional.

If we now compare the condition of the cane and the salt content
of the soils we find that the cane is the better, the smaller the quantity of
chlorides plus bicarbonates, and that the cane gradually becomes worse,
as that quantity increases. With .408% of bicarbonic acid plus chlorine
the cane is quite normal, and even with .543% it still makes a pretty
good showing.

Combining these results with those of the second series of analyses,
we reach the final conclusion that cane in these marsh lands grows
well where the sum of bicarbonic acid ion and of chlorine does not exceed
0.4^ , always provided that the level of the ground water is low enough
to prevent the cane roots from coming in conlaet with it. Tf the sum of

39

bicarbonic acid and chlorine rises above 0.4 to 0.5%, the cane begins to
suffer visibly, even though it be not growing in standing water.

These figures can, of course, not be considered as a standard in all
cases, because a number of other factors influence their magnitude to a
greater or lesser extent. Thus the proportion of chlorine to bicarbonic
acid may in practice vary within wide limits. Then the influence of the
sulfates has to be taken into account, as is so well shown in the study of
the second series of analyses. Moreover, the soil of the marsh is not
uniform throughout, and its texture and other physical properties and
its chemical composition may largely affect the relation between the
salt content and the growth of the cane. But it would be virtually im-
possible to find all these conditions represented in the field in such a
way that each factor may be studied by itself to the exclusion of all
other factors. We must therefore be content with such indications as are
afforded by the data given in this report ; and in order to study all of the
points just mentioned, it will be necessary to carry out experiments with
all conditions under perfect control so that each factor may be studied
separately. Such investigations will necessarily have to be made in
tubs.

For all practical purposes we may conclude that, at least in this
marsh, and in such places where the ground water is sufficiently low, to
be out of the reach of the cane roots, the sum of bicarbonic acid and of
chlorine may safely rise to 0.4$ , but must be lower where that condition
is not fulfilled.

OTHER MARSH AREAS.

A few samples of soil were collected in other marshes' on the north
coast, and it was found that some of them are extremely salty. The anal-
yses are compiled in table XV.

TABLE XV.

1 2

3

4

5

Carbonic acid, as (CO 3) .000 .000
Bicarbonic, acid,as(HCO 3)2 .843 trace
Chlorine . 142 1.758

.000
trace
1.194

.000
.105
.115

,000
.147
.081

Sulfuric acid (S04)

(HC03 ) 2+C1 2 .985 1.758

1.194

.061
.220

.033
.228

Sample No. 1 is from the Tortuguero, near Manati, and was collected
by Mr. Howells.

Nos. 2 and 3 were taken in the marsh surrounding the Laguna de
San Jose. "\ ,

Nos. 4 and 5 are samples from a marsh belonging to the estate
controlled by the San Vicente Sugar Company. The general formation of
this marsh is the same as that of the Cafio de Tiburones; it consists of

40

the characteristic black surface soil and the white calcareous subsoil.
Here, according to Mr. Crawley, the water is very near the surface so
that the cane roots are in contact with it.

We find that in samples Nos. 1 to 3 the salt content is exceedingly
high, and so far only typical salt plants grow in these soils'.

Nos. 4 and 5 are interesting samples inasmuch as they bear out our
conclusion arrived at above, that the cane will in marsh lands stand much
less salt when it is growing in standing water than when its roots are not
in contact with the ground water. In fact, the cane at that place is not
growing well.

RECLAMATION OP THE MARSHES.

In the preceding chapters we have ascertained the trouble that
prevents the cane from growing normally in these salt marshes and have
found out under which conditions it will grow well. We now come to
the question as to how these conditions may in practice be arrived at
with the least possible expense. The first necessity is, as we have seen,
the lowering of the water level. This would be indispensable, even if
the water did not contain salt, since, as is well known, cane is a plant
that requires excellent drainage. However, as the water in this marsh,
is not fresh water, but, on the contrary, highly charged with salts, drainage
becomes absolutely imperative. We have seen that around the center of
the swamp, about stations 3 and 4 of Series 2, the salt content is exceed-
ingly high, and the counteracting sulfates are low. By dropping the water
level sufficiently the trouble can be remedied, and regular floods which at
present are a great danger to the cane in wet weather, will thus be
avoided. After good drainage has been provided the excess of salt must
be washed out, by the natural rainfall, and, if necessary, by the aid of
irrigation, until the concentration of the salts falls below the danger
point as indicated by the results of our investigations. But before an
attempt is made to leach out the salts, an excellent drainage system must
first be installed. Unless this be done, always forcing the water to move
in a downward direction, it will dissolve the salts out of the lower soil
strata, then rise by capillary action, and on evaporation will leave more
salts in the surface layer than there were before. It will be well to quote
Maxwell's own words in this connection C1). "The salt content of the
soil and its action upon the growing crop can be modified by the amount
and quality of the water used in irrigation. 'Sweet' water can carry the
salt down out of reach of the cane roots, but if there is no outlet for the
water through the subsoil, it will come up again by evaporation to the
surface, bringing with it a greater excess of salt to deposit near the
roots. ' '

(1).— O. E -S. Bull. 90, p. 17.

41

A very good beginning towards the iinal reclamation of the (Jaiio de
Tiburones has already been made. The ditches are quite close together
and generally deep enough to carry off the water into the canals. It would
perhaps have been better and more profitable to first completely reclaim
the land before commencing to plant cane, in consideration of the fact
thai, under the conditions obtaining, the operations of planting, culti-
vation and harvesting are extremely expensive and would pay only if the
yield of suger per acre were very high. The preparation of the land,
planting and cultivation had, on account of the very nature of the soil,
to be done entirely by hand and with the greatest care. And, with all
this expense, the quantity of sugar produced per acre was exceedingly
small. We must further consider that the cane, already weakened by the
effect of the salt, is much more liable to suffer from the attacks of insects
and diseases than healthy cane growing in a good soil. In fact, some of
the ratoon cane in the marsh is very heavily infested by the moth stalk

borer.

While, for the reasons alluded to, it would probably have been more
advantageous not to plant cane until the land was in a condition for
growing it successfully, a large area of the swamp, about 2000 acres, has
already been planted to cane, and the reclamation work has to be carried
on simultaneously with the cane cultivation. Since the summer of 1911
good progress has been made in this direction, and the water level has
fallen about six to eight inches. Even this improvement has been
accompanied by excellent results. The ratoon cane this year presents a
much better appearance than the plant cane, although the salt content,
according to some analyses made lately, is on the average about the same
as last year. But the natural limit in lowering the water level has now
about been reached. At the present time the entire difference in level
between the center of the swamp and its outlet at the Arecibo River, is
only 1.20 meters, or only 10 centimeters per kilometer. This slight grade
will hardly be sufficient to quickly drain the marsh. It must, moreover,
be considered that the black soil shrinks very much on drying, so that
the surface of the soil sinks, thus again raising the wrater level. It follows
that a more effective system of drainage must be installed, as for
instance by dikes and pumps.

With an efficient system of drainage it will be easy to get rid of the
salts. It is quite probable that the rains may be sufficient to accomplish
this. If the year, should, however, be dry, then irrigation may have to
be resorted to.

After the soil has finally and definitely settled, it may be found
advantageous to replace the open ditches by a system of tile drains in
order to avoid all the difficulties arising from the close proximity of the
ditches; this always provided that the character of the soil permit the
use of tiles.

42

In the meantime it would be well to carry out some experiments on
fertilization, in order to find out what fertilizers will bring the largest
returns. This question has already been discussed at length on pages
(10-14), to which we refer the reader.

It is sincerely to be hoped and it seems now quite certain that these
marsh lands after being thoroughly reclaimed and when cultivated
according to the best known methods of agricultural practice, will finally
produce good crops of cane, and thus contribute their share to the wealth
of this beautiful island.