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Cornell Universit

Irrigation(proceedings of a meeting of

(English Edition)

EXPERIMENT STATION
of the

SUGAR PRODUCERS’ ASSOCIATION OF
PORTO RICO.

RIO PIEDRAS, P. R.

IRRIGATION

(Proceedings of a Meeting of Sugar Planters, Held at Central
Fajardo, August 15, 1912),

THE TIMES PUBLISHING Co.

1912

Cornell University

Library

The original of this book is in
the Cornell University Library.

There are no known copyright restrictions in
the United States on the use of the text.

http://www.archive.org/details/cu31924003374851

(English Edition)

EXPERIMENT STATION
of the

SUGAR PRODUCERS’ ASSOCIATION OF
% PORTO RICO.

RIO PIEDRAS, P. R.

IRRIGATION

(Proceedings of a Meeting of Sugar Planters, Held at Central
Fajardo, August 15, 1912),

THE TIMES PUBLISHING Co,

SUGAR PRODUCERS’ ASSOCIATION OF PORTO RICO
145578

OPFIGCERS.
Ramon Aboy Benitez...... .. ..¢ sees... President
Antonio 5; Aleaide:....1 .:e.csecearsvaevesp, MicesPresident
Agustin Navarrete.... 2... 0.2 e eee eee Secretary
DIRECTORS.

A. J. Greif T. G. 1, Waymouth

Jorge Bird Arias L. H. Farnum

Eduardo Giorgetti Lucas P. Valdivieso

Rafael Fabian Arturo Quintero

Luis Rubert

EXPERIMENT STATION STAFF.

J. T. Crawley.... .............. .... Director
D. L. Van Dine................ 00000. Entomologist
J. R. Johnston.....,.............. .. Phathologist
F. W. Zerban................ ...... Chemist

H. B. Cowgill... . Titian 2st
We Tale JOmessc, cies deat erates
My, Gabréta... cog cc cece cee 86 be ee en

Assistant Pathologist
. Assistant Entomologist

. Stenographer & Translator

TABLE OF CONTENTS

Page.
Introductions, ah: vavheono Sc oe oa ee ta 4
Irrigation, by J. T. Crawley................ ha (eli nee 6

Discussion on Irrigation at a meeting of the planters at
Fajardo on August 15, 1912, by W. W. Schlecht... .... 12

Preparation and Cultivation of the Soil with the purpose of

“ Conserving Moisture, by J. T. Crawley...... sega 16
Rainfall at Arecibo, by J T. Crawley...........00..0.. 20
Irrigation, by E. E. Olding...... 0.00 ..0.0.0 ce cece cee ees 23

INTRODUCTION.

The papers which are herewith published were prepared for pre-
sentation at meetings of sugar planters called at Central Fajardo on
August the 15th and at Arecibo on August the 25th. The meeting at
Fajardo was well attended and the interest shown in the procceedings
by all those present was an indication of the importance of the subject
chosen for discussion. As will be seen by reading these reports,
there has been an almost unprecedented drouth in many parts of the
island which in some parts began last year and with but few exceptions
has continued until the present time. The object of the meetings was
to confer with the planters and discuss the possibility and practicabil-
ity of installing cheap but efficient irrigation plants that would assist
in the future in diminishing the disastrous effects of drouths. The
Commissioner of the Interior recognized the importance of the matter
and at our request sent Mr. W. W. Schlecht. a practical irrigation
engineer of the Irrigation Service, to Fajardo to look over the situation
and be present at the conference.

At the same time it was considered a very opportune occasion to
discuss the methods of conserving soil moisture by methods of prepa-
ration and cultivation of the soil as it is believed that proper methods
of cultivation will tend greatly to mitigate the bad effects of seasons
of drouth. The statistics of rainfall do not extend over a_ period
sufficiently long to enable one to speak with confidence, and yet a
careful consideration of all data available leads one to believe that in
many places drouths are of frequent recurrence, so frequent as to make
irrigation and moisture conservation of great practical importance.
My own impression is that so much attention has been paid to the
drainage of cultivated fields, (in fact the systems of preparation of the
land and planting seem to be with that chief end in view) that the
planters have forgotten that as much harm may be done to eine by
having too Jittle water as by having too much.

Unfortunately no meeting was held at Arecibo, owing to the fact
a preparations for a meeting place were not made until it was too

ate.

The Experiment Station has been very desirous of vetting the
people generally interested in holding meetings and discussing with
them practical plantation problems. There are some subjects of a
more or less scientific aspect, such as injurious insectsand cane diseases,
fertilization, etc., in the discussion of which the staff of this Station
should be leaders and teachers, but there are many practical details
of plantation work and plantation problems that the planters alone
understand. There is such a cloze relation between the scientific and
practical aspects of these subjects that meetings of all parties should
result in much mutual benefit. In most cane-growing countries such
meetings are held periodically, and all the more important questions

5

are discussed, but in Porto Rico, it seemed best to hold a number of
conferences in the various sections, rather than to depend on having
one large meeting where all the sections would be represented. Meet-
ings have thus been held at Ponce, Rio Piedras, San German and
Fajardo and the intelligent interest on the part of the planters en-
courages us to hope that they have been of some value. They at least
tend to foster a spirit of inquiry and cooperation that is essential in
building up and maintaining any large and commanding industry.

J. T. CRAWLEY,
Director.

IRRIGATION
By J. T. CRAWLEY.

The subject of irrigation has hitherto received but little attention
on the part of the sugar planters of the north and east coasts, partly
owing to the fact that drouths are rare, and the rainfall is sufficient
for securing large crops of cane. The extended drouth of the past two
years, however, has done so much damage that I think you will agree
with me that the subject is of sufficient importance to be seriously and
carefully considered. ones

The sugar cane isa plant that requires a great deal of water, in fact
it is one that responds very quickly to water whether this be from
rainfall or irrigation. Although normally the rainfall is sufficient for
large crops [ believe there are many years when irrigation would
pay, and in times of drouth like the present, a few thousand dollars
spent on pumps and ditches would save hundreds of thousands. While
it is not necessary to the maintenance of the sugar business in this
vicinity to establish irrigation, yet it would be an insurance. You
spend thousands of dollars in insuring against fire, in insuring against
accident, and Joss of life, in insuring against cyclones, and insuring
your sugar on its way to market. But the basis of all of this, of all of
your wealth, of your living itself, is the crop of cane. In the final
analysis it is the cane itself that gives work to your laborers, work to
your Centrals, and wealth to the country, and it is not insured. In
times like the present this necessity of insuring against drouth forcibly
presents itself, and I believe that irrigation in the valleys of the north
and east coasts could be very cheaply and effectively introduced. You
have large streams of pure water very near the surface of the ground,
and the cost of pumping this on to the land would be very small.
Again the ground water is near the surface and is apparently abundant.
There are three principal ways of securing the water, first by inter-
cepting the streams at an elevated point, and bringing the water to the
plantations by gravity, second by pumping direct from the streams to
the land, and third, by digging wells and pumping. The first would
in most cases probably be the most expensive as it would necessitate
long lines of ditches, but after these are established the cost of upkeep
should be very small, and you would never have the cost of fuel, pumps
and repairs to the same, ditches, etc.

In Bulletin No- 17 of the Estaci6n Agronédmica of Cuba, there is
a record of some results of irrigating in Hawaii.

As an average of 28 tests, 46 inches of rainfall produced 1,600
lbs. of sugar per acre, while 48 inches of irrigation applied at proper
times, in addition to this 46 inches of rainfall produced 12 tons of
sugar per acre.

During a period of three years beginning in 1898 and ending in
1900, the following crops were produced:

7 ;
TABLE SHOWING AMOUNT OF WATER USED AND
SUGAR PRODUCED.

Year Water used per acre Sugar produced.

1898 2.5 millon gals. 14.5 tons

1899 2.8 ay ee 17 ae

1900 3. Be uf 20 u ratoon crop.

1900 3.30% ee 18 : plant we

1900 5.5 f ve 27 ss es ‘¢ 1 plot only

These figures are very instructive and show that the yield of sugar
was almost proportional to the amount of water applied to the cane,
and illustrates what wonderful results are possible with good soil,
plenty of fertilizer, and plenty of water.

You have in Fajardo a very great advantage in that your soils are
heavy and hold the water fora long time. Frequent irrigations then,
even in times of drouth would not be necessary. In fact I believe
that a very few irrigations per year would be sufficient in most years
to maintain the proper amount of moisture in the soil for good crops
of cane. Your method of planting cane would have to be changed,
but this would also be a benefit rather than a detriment. Where irri-
gation is practiced the cane is placed in deep furrows, ‘‘chorro’’, and
water is run directly in these furrows. For ratoons you would either
run the water in the cane row, or hill up the ratoons, making a
depression between the rows into which the water is run. Whenever
irrigation is adopted you use more fertilizers, for fertilizers pay best
where there is an ample supply of water.

The following table gives the rainfall at Fajardo for the past 13
years the same having been furnished by the U. S. Weater Bureau at
San Juan:

8

Taste I.—RainraLy at FasARDO.

Year} Jan. | Feb.| Mar. {| Apr. | May | June | July | Aug | Sept. | Oct. | Nov. | Dec.
1899) 4.53) 1.20} 2.26; 8.00) 6.00] 5.88) 5.58] 621] 6.13} 17.07] 17.80) 3.50
1900] 4.44) | .65} 2.15] 13.77| 2.94) 14.35] 5.43] 8.25] 10.00] 7.62) 3.42) 344
1901) 6.07| 1.34] 3.90} 3.03) 7.13} 8.16) 16.01] 290] 9.03} 8.81) 14.87) 6.71
1902} 5.56] .10) 2.60} 3.92] 8.04] 16.29} 4.28} 3.24) 5.49) 3.21) 867) 447
1903) 1.33) .90] 2.241 2.93) 5.90] 3 45) 8.83] 9.44) 342} 9.87| 5.87) 6.43
1904] 1.93] 3.80] 4.96] 4.57) 5.26] 3.03) 4.41) 4.25! 9.64) 13.55] 10.93) 2.73
1905) 6.65) 2.12] 4.76} 2.00] 8 97] 38.43) 344) 7.75] 7.30) 14.43) 9.26) 3.85
1906] 1.30) 2.00] 3.93] 1.95] 3.58} 7.21] 8.08) 1.81} 14.04 3.21} 6.04) 7.65
1907] 2.48) 3.09] 2.66] 1.33] 5.27] 4.36} 5.07) 3.06] 4.97] 7.02) 5.85] 10.42
1908] 5.02} 3.59] 3.95) 1.16) 5.50] 4.50) 2.82} 3.99) 9.63) 4.57) 7.73) 5.57
1909] 1.55) 5.89] 3.59) 2.56] 3.59} 8.83] 3.04] 14.63] 4.27] 8.00) 16.23) 2.03
1910] 5 28) 2 39) 5.86] 3.09) 6.57) 1.27] 4.00] 4.87} 12.92] 4.94) 463) 6.49
1911) 4.34) 5.52} 0.93! 3.52) 8.85} 1.94) 6.18} ..27] 5.92; 5.-5) 3.05) 14.54
1912) 1.14] 1.94] 2.31) 5.51! 3.42) 3.04] 178) — — — _— ee

Means| 3.68] 2.47| 3.26) 4.24) 6.34] 6.85] 5.62) 5.82/ 7.90) 824) 872] 5.22

For our purpose we should have the rainfall for a great number
of years so as to be able to predict the frequency and probable severity
of drouths. Any month with less than five inches of rain, unless
preceeded by heavy rainfall, may be considered as a dry month. Cane
should have 5 inchestoinsure a good growth. Taking this as our
basis let us see how often you have drouths in this neighborhood and
how long they last.

The years 1899, 1900, 1901 and 1902 were practically without
drouths except for periods of two or three months that did little harm
to the cane. The first recorded drouth was that of 1903 which began
in January and ended in July. This was almost as severe as the present
drouth, but it was broken earlier. In 1904 there was still longer
period of drouth, which ended only in September. 1905 was a good
year, as also 1906, except for a long spring drouth. 1907 was another
dry year, the drouth beginning in January and ending in October.
1908 was dry from February until September, or throughout the prin-
cipal growing period. Both 1910 and 1911 had dry springs and com.
paratively dry in midsummer but on the whole th> rainfall was fairly
satisfactory. The drouth of the present year begin in January, and
has not yet ended, with but 19.14 inches for the first seven months of
the vear.

Figure I gives the mean monthly rainfall at Fajardo for the period
covered by our statistics.

9

Fieure 1.—RaInFALL AT FasaRDO.
(The numbers indicate inches of rainfall).

ew

sn Feb Mar Apr May Jun Jul Acg Sep Oct Nov Dee
: | | ? jg
f F

alll

N

gy

r/ Pomerat Bt A
a a Cra
ks as wa las 3
7y S” C7
2 2.
re 7-
Lf 2.

Taking the average of 13 years, the spring drouth begins in
December and ends in May, followed in many cases by shorter periods
of small rainfall in June and July. October and November are almost
always wet, and September is usually so

It is fortunate that the drouth in the spring comes at the time
when the cane is being harvested, otherwise harvesting would be
difficult, but fall plant cane gets a check to its growth from which it
is often difficult to recover. With a convenient system of irrigation
this cane could be kept growing until the summer rains come. With
irrigation one could also give a quicker start to the ratoons in the
spring. But to my mind the greatest damage is done in the years of
summer drouths, and especially those, as in 1904, 1907, 1908 and 1912,
which are preceeded by dry spring months.

This is a period when the cane should be in full growth, fall plant
as well as spring plant and ratoons. It is the hottest time of the year,
plant growth is most active, evaporation from the plant and from the
soil is the greatest, in fact the time when the greatest drain is made
on the soil moisture.

You might say that this is the critical period of the year, which
in a large measure determines what the next crop shall be.

10

Method of irrigation of cane.—Various methods of supplying
the water to the cane will suggest themselves to the planter, and
methods have to be devised to suit the circumstances. Fig. 2 will
illustrate one system where the land is comparatively level and where,
as is often the case in Porto Rico, drainage has to be carefully provided
for. Ais the ditch carrying the water; B and D are small ditches
passing through the field at right angles to the rows of cane, a, 8, ¢, @,
etc., and C, H’are drainage ditches. The water is brought down the
ditch and into the cane rows, one at a time, on either side, and is
allowed to run until it reaches the drainage ditches, which are parallel
to the irrigation ditches, when it is cut off and run into the next row.
This will be seen by reference to the figure, the water is run into D
and from there into row a until it reaches drainage ditch C on one side
and £ on the other, it is then stopped and turned into row 6, and so on
for the whole field. Where the field is not level, it would probably be
more convenient to run the irrigating ditches parallel to the drainage
ditches, and at a distance of two or three feet. The water is run into
the cane rows on one side only and allowed to flow until it reaches the
next drainage ditch. Suppose the fall of the land in the figure is from
Ato Hand B, C, D, and £, are the drainage ditches, then the water
is run in shallow furrows on the lower side of each one of these, and
led successively into the cane rows. The appearance of the rows is as
represented in the figure, 2, m, n, etc., being the bottom of the furrows
where the cane is planted and into which water is run.

11

‘aNVO GZHI JO ADVYNIVUC ANV NOILVOIENT—"Z “SIT

DISCUSSION ON IRRIGATION AT A MEETING OF THE
PLANTERS AT FAJARDO ON AUGUST 15, 19 2.

By W. W. SCHLECHT.

Irrigation was first introduced in regions were the rainfall was
deficient for the growing of any crops, but it is now being rapidly
extended to regions where, although crops may be grown, the rainfall
at times, especially during the growing season, is too scant to produce
the best and largest yields. In order best to satisfy the conditions
of plant growth, the moisture should never fail from the time of plant-
ing until the crop is fully matured, and there are certain times when
the cessation of the supply will do more harm than at others. This
applies to sugar-cane, for which a drought during February or March
is not very harmful, but should a similar drought occur during the
growing season, from June to November, the yield is decreased by a
large percentage. Irrigation by supplementing the rainfall does away
with the element of chance, makes the crop larger and better and eli-
minates failures.

In order to determine the extent to which this region (Fajardo)
requires irrigation, the same table of duty of water which was assumed
by the Porto Rico Irrigation Service has been used. It is assumed
that sugar-cane requires 72 inches of moisture during a year. This
may be rainfall or irrigation water. This gives an average of 6 inches
per month, but it is furthermore assumed that shortly after cutting
or planting and also while maturing and also during the 20 weeks of
harvesting the needs are not as great as during the growing season,
and based on these assumptions, a table of montbly requirements of
moisture or ‘‘duty of water’? has been compiled. This it is assumed
will, in @ general way, apply to this region.

DUTY OF WATER.

January, 6.0 inches July, 6.1 inches
February, 5.3 ” August, 6.5 °%
March, 45 September, 7.0
April, 40 ” October, 7.6 ”
May, 4.6 ” November, 7.8 ”
June 5.7 December, 6.9 ”

Total, 72.0 inches.

Combining these requirements of moisture with the rainfall reccrd
observed at the Station at Fajardo gives the amount of irrigation water
that should be applied to the land to obtain the best results.

The table shows that during the past three months, from May 15th
to August 15th, which are in the growing season, there was a deficiency
of 12 inches of moisture. This, as can be seen by passing through the

13

cane fields,has seriously stunted the growth. Now in studying the table
we find that practically each year has a month during the growing season
in which the moisture is deficient, although there are only two seasons,
i. e., from July to October, 1912, and from October 1906 to January
1907, in which the drought was almost as serious as this year’s. The
table furthermore shows that, in addition to the rainfall, the land
requires an average of 25 inches of moisture, to produce the best results,
the maximum being about 30 inches, and the minimum about 15 inches.
This compares favorably with the cane fields along the south side of
the island, where the irrigation requirements are from 30 to 60 inches,
and where the irrigation is of vital importance. Due to this fact,
you must not expect to pay as much for irrigation as the people
on the south side.

Although it is assumed that the land requires an addition of 25
inches of moisture during an average year, the amount to be provided
by irrigation must be greater, thidiue to the losses in the canal and
laterals and in the fields themselvs. These losses in a new system
before the canals and laterals are primed, are rarely less than 50%,
and in an old and well built system are rarely under 20%.

It is now assumed that this region (Fajardo) needs irrigation,
although intermittent, and that the sources of supply are next to be
discussed. The first and generally the cheapest source of supply isa
perennial stream, and after the natural flow of this is developed, a
reservoir to hold back the flow for use in the periods of drought, can
generally be built cheaper that a pumping plant, deriving its supply
from wells driven into the underground reservoir, giving due consi-
deration to operating and maintenance charges.

At present you have a large and undeveloped flow in the Fajardo,
Mameyes, Blanco and the small streams of this vicinity, which can be
utilized for irrigation very cheaply, but it is apparent that there is
more land to be irrigated during the periods of drought than can be
supplied by the natural flow of these streams, and that sooner or later
additional development will be desired. Now surveys of land can
always be made in a short space of time, but due to the ever-varying
flow of a river from day to day, from month to month from season
to season and from year to year, it is necessary to have a consecutive
record of the height and discharge of a stream extending over several
years before any plans can be drawn for the complete utilization of
the water furnished by these streams. Fora partial development such
as you are making now, such a record is not very important, but the
time will come when it will be desired to irrigate additional lands that
such a record will be very valuable.

Yesterday morning (August 14th) the Fajardo River was dischar-
giny 1,250 liters per second, or about 29 million gallons per day, but
at that time it was not at its lowest stage, and since no record is
available, low flow of more than 550 liters per second cannot be as-
sumed with safety for a period of drought. This would irrigate
approximately 1,500 acres, provided irrigation was carried on through
out the 24 hours of the day, and leave an ample margin for losses-
in theirrigation system of evaporation and seepage. In addition to
this land irrigated by the Fajardo River, a large area can also
be irrigated by the other streams of this vicinity.

In order to irrigate land by gravity, the following structures are
generally needed:

14

1. Diversion works.

2. The main canal, with its structures, such as tunnels,
siphons, flumes, spillways, bridges, culverts, etc. Tun-
nels and siphons are the most expensive structures,
but the number of these for this region appears to be
small, consequently the cost of the canal should not
be high.

3. The field laterals. :

4. The preparation of the irrigated area to receive water,
such as leveling, furrowing or checking.

The major portion of the losses in an irrigation system occurs
in the small laterals and in the irrigated field, generally due to the
fact that the carrying capacity of the field laterals is too small and
that consequently the water, instead of covering the area which it is
intended to irrigate, sinks into the ground at the upper end of the
lateral and leaves the lower end with a deficient supply. Furthermore,
the land must be prepared very carefully for irrigation. A little time
and money devoted in the beginning to a proper preparation of the
land will be more than repaid in the saving of the water and the ease
and cheapness with which it can be applied. Land once properly
prepared can always be cheaply and easily maintained in the best
condition. Where land is properly prepared one man can quickly
and thoroughly handle water on 10 acres; whereas, two or three men
will not produce as satisfactory results on the same area poorly graded
and prepared.

Where water is to be applied by the flooding method great care
should be taken to produce a perfectly uniform slope and surface.
This should be done by the use of some of the grading tools which are
now on the market, in connection with levels taken to determine
within an inch or two as maximum limits the slope of the land. If
the surface is particularly uniform, deep ploughing followed by
harrowing and then dragging over the surface a heavy log or beam or
some other device for leveling the land will suffice. At other times
the slope may be too great to permit of irrigation by flooding, because
it would produce such a velocity as to cause erosion of the soil. This
is to be corrected by grading the soil so as to form checks or in
extreme cases by terracing, which is but an exaggerated form of check.
If the surface is uneven the water will stand about in pools, so that cer-
tain portions of the land wili receive too much and become supersat-
urated while other places will be high and dry. It is only, therefore,
by the creation of a uniform surface that water can be satisfactorily
applied by the flooding method.

Where the soil is to be prepared for irrigation by furrows, and
especially where these furrows are to be small and narrow, even greater
care must be taken than in the flooding method in producing the
proper slope and surface level. Ifthe slope of the land is too steep
the furrows will, because of the velocity of the water, be rapidly
eroded. If the slope is too slight the water may take so long in flowing
across the fields as to be all evaporated or absorbed before it reaches
the further end. Too steep slopes may be rectified by running small
ditches or flumes down the slope of the ground and inserting falls in
them to overcome excess of slope, and by turning the water from
these into lateral furrows and drills which run at such an angle as
procures the proper fall.

15

The moistening of the roots by sidewise percolation from shallow
furrows is not nearly so complete as generally supposed, the general
movement of the water being downward, therefore, in conclusion, it
it may be stated that many field laterals are built too deep in the
ground.

Fajardo, August 15, 1912.

PREPARATION AND CULTIVATION OF THE SOIL
FOR THE PURPOSE OF CONSERVING MOISTURE

By J.T. CRAWLEY.

You are all agreed as to the important role played by water in
the production of all crops, and especially in that of sugar cane.
Without an ample supply of water whether from irrigation or rainfall
it is impossible to grow satisfactory crops of cane, and it is quite Im-
portant to know how to preserve the moisture in the soil after it has
been secured. Eighty inches of rainfall is sufficient to produce good
crops, providing all, or the greatest. part is utilized—that is, providing
it falls with comparative regularity, and that your methods of culti-
vation are such as to preserve it for the uses of the crop. If these
eighty inches fall irregularly, that is in heavy storms, with long
periods of drouth intervening, it may be insufficient. When drouths
come, as the present one, long continued and severe, it emphasizes the
fact that every means possible should be used to mitigate its evils.
After the drouth has come and the cane is dying there is but little
in the way of cultivation that can be done. But systems of preparation
of soil and cultivation can and should be adopted that will tend to
make drouths less severe.

What I am going to say is at the very foundation of agricultural
science, facts and principles so well established as to seem elementary
and simple.

It is much more important that the water coming as rainfall. that
costs nothing, neither for the supply nor for the application of it, he
utilized, than that you should provide expensive systems of irrigation.
There are two distinct questions, first, how shall we secure the b-
sorption of the water by the soil and second, how shall we prevent its
being evaporated from the soil after it has been absorbed.

Absorption of wuter by soils.--The amount of water that a soil
can absorb depends on two principal factors. In the first place, it
depends on the size and nature of the particles composing the soil,
and in the second place on the arrangement of these particles. The
water is tiken up in the spaces betwen the particles, and the
greater the space between these particles, the greater will be the
amount of water absorbed.

Assuming that all soil particles are spherical, it has been calculated
that with the closet possible arrangement of the particles with re-
ference to each other, there would be a pore space between these
particles of 25.95 per cent of the volume of the soil, and a soil of this
kind could take up 24 95% of water. If however, these particles be
arranged so ns to give the greatest pore space, the soil could absorb
74.05% of water. Now on standing unmoved for a long time the soli
particles become packed together with but little pore space, and in

1%

this condition can absorb but little water. But on being loosened up
whether by the plow or hoe, the particles assume a more open position,
the pore space is therefore enlarged, as well as the capacity of the
soil to absorb water.

_ One method then of promoting the absorption of water by the
soil, is to break up the soil thus increasing its volume and pore space.
You are familiar with the fact that when you plow four inches deep,
measured along the cut surface of the unplowed land, the loose soil
1s at least 6 or 8 inches in depth. Deep and thorough plowing in the
preparation for planting cane is then of the greatest importance. It
not only gives a loose soil for the growing of the roots but it enables
the soil to take up water for the future uses of the growing plant.

After a crop of cane has beeen taken off, the soil is hard packed
and in this condition it cannot absorb much water nor can the roots of
the young plants penetrate it sufficiently to give the greatest vigor
to the cane. This soil should be broken up as well as possible with
the plow. Subsequent rains will penetrate and be absorbed by the soil,
and by subsequent shallow cultivation the soil will be in a much better
condition to withstand a drouth.

It is easily seen that where one has left ratoons to grow without
plowing, but has made clean smooth ditches every 11 feet. as is the
present custom, much of the rain that falls will run off. This might
happen ata time like the present when it would be very desirable
that all the water falling on the Jand should be caught and preserved
by it.

Another factor that is of the very greatest importance in absorp-
tion of water is o7ganic matter or humus.

Every one knows that a rich virgin soilabsorbs more water and
stays wet a longer time than one that is old and exhausted of its organ-
ic matter. You are also familiar with the fact that the soil in a cane
field is always more moist under the trash than that exposed to the sun.

The following table showing the total absorptive and retentive power
of soils very well illustrates these facts.

Soil No....... 0... 1 2 3 4 5 6

Water absorbed..... 86.9% 73.7% 86.4% 44.3% 4.63% 45.2%
“ retained aft- :
. eronemonth 51.9% 45.9% 52.4% 14.8% 16.8% 18.2%

The first three soils contain much organic matter, while the last

three contain but little.
Following are the amounts of water which were found in three
types of soil when they were saturated under field condition:

Sandy loan ues veved se eo eee Gow 17%
esr lost ci sl ees. a san eon ean eee dleewedes oO
Humus soil. 2. 2... cee cee cece ce eee eee 44%

These facts and figures suggest that the saving of the cane trash
and plowing it into the soil where it will assist in taking up and re-
taining water is of the greatest consequence in warding off the disas-
trous effects of a drouth. But itis just as important that the water
be retained in the soil as that it be absorbed, and we shall now take
up the means of preventing the loss by evaporation from the soils.

Conservation of Sott Moisture.—lf a clean glass tube be stuck in
water, the water will rise in the tube to a height depending on the

18

diameter of the tube. Ina tube 1 inch in diameter the water rises
™7o. inch; in a tube'/zo in. diameter, the water rises ¥g inch; ina
tube oy ost in. diameter, the water rises 5 inches; and in atube Fou in.
diameter, the water will rise 54 inches. Now in a soil at rest
there are fine tubes or spaces between the soil grains themselves,
through which the water rises and passes into the air. After a hard
rain these tubes become smaller since the soil is closely packed, and in
this condition they are very effective in bringing up water. These
tubes bring up an enormous amount of water which is absolutely lost.
Now plowing or cultivating 2 or 3 inches deep breaks up these tubes
and prevents the escape of the water.
Following is the result uf an experiment to determine the effects
of cultivating on the moisture content of the soil, as reported by Snyder
in “Soils and Fertilizers”

Per cent of water in corn field.

With shallow surface Without shallow surface
cultivating cultivating
Soil depth 3 to 9 inches.......... 14.12 8.02
Soil depth 9 to 15 Inches.... ... 17.2) 12.38

Ordinarily one thinks of cultivation as a process for the purpose
of killing weeds and grasses, and therefore when these are killed
cultivating stops. But this isa great mistake and during dry spells,
cultivation should be kept up for the purpose of maintaining a cover-
ing of loose soil of 2 or 3 inches in order not to lose the little water
that you already have in the gruund. This is especially needed after a
hard, packing shower. A hard shower of short duration may actually
do more harm than good during a drouth. The water does not enter
the soil to a sufficient depth to be of benefit to the roots, the sun dries
out the surface which becomes baked and cracked in consequence, and,
what is worse, they vpen up communication with the moisture already
in the soil, causing that to be drawn to the surface and lost.

In an example mentioned by Snyder. tests, were made of the
amount of water in the soil before and after a shower, with the follow-
ing results:

Per cent of water

Surface soil 1 to 3 inches Subsoil 6 to 12 inches
Before the shower.............. 9.77 18.22
After “‘ BNP hae) Meare 22.11 16.70
Gain.. 12.34 Loss . 1.52

Now there was but enough water to raise the percentage in the
surface 11%, therefore the 1.34% extra that it contained came from
the subsoil, which itself had lost one and a half per cent.” This is just
what has happened in this neighborhood. The drouth began in January,
after a very heavy rainfall in December. At Santa Rita there have
been 20 weeks with showers from .04 in. to. 83 in These showers have

19

not only been of little use te the growing crops, but in many cases
have doubtless done damage in the way already indicated.

From the foregoing we see that:

In order that the soil shall take up a large quantity of water,
preparation of soil must be deep and thorough, and the trash plowed
into the soil, and to conserve mvisture after it has been absorbed by
the soil frequent and shallow cultivation should be practiced.

I venture to say that those in this community who have followed
these practices are suffering less from the present drouth than those
who have not practiced them.

DISCUSSION

It is to be regretted that no stenographic notes of the discussions
were made. The general opinion seemed to be that furrow planting
could be adopted in many parts of Fajardo and that this would simplify
irrigation should that be necessary. The water could thus be brought
to the cane along these furrows. However, in places where the soils
are very wet and heavy the present system of ‘* banco’’ and ‘‘ gran
banco’’ will have to be continued, owing to the heavy and continued
rainfall that may be expected at certain seasons of the year. Deep
plowing for the purpose of conserving moisture and subsoiling as an
aid to drainage were advocated, but it was maintained by some of those
present that owing to the difficulty of plowing the heavy lands of Fa-
jardo, thorough preparation could not be secured unless the acreage
was reduced; in other words that it was a question between extensive
and intensive planting. So long as large areas are planted to cane
neither thorough preparation of the soil nor ad:quate subsequent
cultivation could be secured, and it was a question if a reduction of
the planted area would be compensated for by the increased yield that
might be secured. The question therefore becomes an industrial as
well as an agricultural one. :

The subject of the cultivation of ratoons was considered of great
importance as bearing on possible drouths. Trash should be saved and
incorporated with the soil, and never burned, unless there were special
and urgent reasons for this course—should insects become very nu-
merous and work much damage to the cane it might be necessary to
burn the trash in order to check the insects, but it was agreed that in
most other cases burning of the trash is a mistake. The ratvons should
be kept cultivated—this was considered essential to retain moisture,
and especially in those soils that tend to bake and crack on drying.

RAINFALL AT ARECIBO,

By J.T. CRAWLEY.

The following table gives the rainfal! at Arecibo since January lst,
1900, except the latter half of 1905 and all of 1906 and 1907.

TABLE II. RAINFALL AT ARECIBO.

Year | Jan. | Feb. | Mar. | Apr. May | June July Aug: Sept. Oct. Nov. Dec.

1900} 2.50} .87} 1.55) 5.38) 3.16} 7.43) 4.84) 4.25) 3.59; 4.79) 6.28) 5.89
1901) 3.04) 1.40] 7.59) 7.63) 8.25) 4.25; 5.62} 2.72) 6.05) 11.74) 16.36) 8.15
1902)10.47; .15} 5.01) 4.84) 9.63) 4.60) 7.67) 7.54) 3.26] 3.38) 6.09] 5.50
1903} 1.53) 1.25) 4.74) 3.97) 8.43) 3.10) 5.15) 4.87) 5.73) 5.29} 5.05) 7.90
1904} 2.00) 8.53) 4.15) 4.30) 3.17) 2.82; 2.77) 4.43) 7.15) 3.87) 1.13) 2.65
1905) 3.72] 2.85} 2.80) 1.85, 4.88
1906 :
1907
1908] 2.00] 5.00} 5.00) 3.28) 3.27) 3.20) 3.27) 2.56) 5.65) 4.87) 7.89) §.77
1909] 1.64) 4.60} 1.69) 1.21) 3.14) 4.15] 4.92) 11.12) 2.80] 4.10) 13.80) 4.50
1910} 7.61) 2.70] 2.75) 1.85) 2.75) 2.87; 4.90) 5.25! 5.80) 3.25} 2.00) 7.88
1911] 12.20) 1.85} 1.65) 5.75, 5.25) = .30) 3.55) 2.55) 3.30) 3.95) 1.20) 7.65
1912} .85} 1.15} 1.80} 3.80) 2.60) .75) 6.19

Means| 4.32} 2.72} 2.52) 3.91} 4.96) 3.35) 4.89) 5.03) 4.91] 5.03] 6.64] 6.54

The record covers a very short period, but it is nevertheless
interesting and valuable.

In 1900 there was a drouth of medium severity begioning in
January and ending in June, but if you had been prepared to irrigate,
you would have ir-igated practically the whole year except June, July,
November and December.

j901—was dry in January and February, and again for a short
time in mid-summer.

1902—was practically without drouth, though water could have
been applied with advantage to the September and October planting.

1903—A drouth began in January and ended in May.

1904—A drouth began in April and lasted throughout the summer.

1905—The whole time up to the end of May was dry. No further
records.

1908—Five months of spring and summer were dry.

1909—Drouth lasted until the end of June.

1910—Drouth began in February and ended in August, though
October and November were also dry.

In 1911 there were two dry periods, but the first did no damage
since it occurred after the heavy rains of Januury, but a severe drouth

21

began in June, and with the exception of December, when good rains
fell, has lasted to the present time. Even July with 6.19 inches of
rain can be considered as a part of the drouth period since 6 inches of
rain after such a long drouth is not sufficient to bring the cane to a
normal condition,

Taking the means of 1U years the drouth begins in January and ends
only in July. During January, February and March it does little
damage except as to retarding the spring plant, but the chief damage
is done in the months of April, May and June.

During the past 10 years or 120 months, I should say that you
have had 67 dry and 53 wet months.

Fig. IIL. gives the mean monthly rainfall at Arecibo during the
time covered by the table, also the mean monthly rainfall at Manati
beginning in January, 1899 and ending July 31, 1912. It will be seen
that the rainfall at Mana‘i is uniformly higher than that at Arecibo,
and it is probable that the curve of rainfall in the large sugar belt
between the two places would fall between the curves given in fig. III
though we have no data to support this assumption.

For comparison we give in the figure the average rainfall as record-
ed at all the Stations of the island by the U. S. Weather Bureau for
the period 1899 to 1909.

It is a fact that will probably surprise the people of Arecibo that
the rainfall at that place both in June and in October is the smallest of
the whole island, as recorded at these 44 stations. In June the average
rainfall was 4.24 inches, followed by Guanica with 4.37 and Santa
Isabel with 4.40 inches, these three stations being the only ones in the
sugar belt with a mean June rainfall of less than 5 inches. In October
the mean rainfall was 5.43 the smallest of the island, being exceeded
by all the stations on the suuthern part of the island where irrigation
is looked upon as a necessity.

Ihave said that the summer is the critical period of the year, as
the greatest growth takes place then. Now the mean rainfall of the
summer months, June, July and August was 14.49 inches, and there
are no other points of the island with less than 14 inches of rainfall
during the summer, except Guanica with 10.39 and Santa Isabel with
11.89. This is exceeded by Guayama with 19.01, by Aguirre with
19.53, and by Yauco with 14.99 inches. I consider these facts of the
greatest moment in the discussion of the irrigation of the lands in the
vicinity of Arecibo.

22

Fic. I.—RAINFALL AT ARECIBO AND MANATHI.

(Also average for the entire Island.)

xX OUD)|

Z -——— ogaady
rf
7 pucysy Jo ab0.10Ny
7 SIONIUIIIY :
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ale a iN ma
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S my pe ” vi i
fa) L . byor a * 7 Z 9
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a a a a a a a

IRRIGATION

By E. E. OLDING.

Where the effective rainfall is deficient for the production of
crops, an abundance of water available for irrigation is one of the
most valuable assets a plantation can have.

Wherever water can be put on the land by gravity, this system is
recommended, even if the cost of canals is much greater than the cost
of pumping water, as the pumps, boilers and pipe lines necessitate a
much greater expense for maintenance. Where canals are well con-
structed the cost of up-keep is very small.

In the Arecibo District the rainfall as shown by the following
table is deficient during an average of five months in each year. The
minimum quantity of water necessary to produce a fair growth of
cane, (as determined by the Hawaiian Experiment Station in 1903) is
taken at 1 inch per week. Taking this as a basis we get the following
shortages of water for Arecibo (see also table of rainfall at Arecibo.)

TABLE No. Ut.

SHOWING MINIMUM SHORTAGE OF RAINFALL AT ARECIBO.

Year 1900 1901 1902 1903 1904 1908 1909 1910° 1911
January.... 1.50 0.96 3.85 2.47 2.00 2.00 2.36 1,30 2.15
February... 3.13 2.60 3.85 2.75 — = 2.31 1.25 2.35
March ..... 2.45 — a — 0.72 2.79 2.15
April....... 0.93 0.73 0.86 125
May .... .. 0.84 0.83 0.80 — 1.13 3.70
June. .... 0.90 118 073 — 0.45
July....... 1.23 1.44 1.45
August.... — 2.72
September. 0.41 — _ 0,74 1.20
October. .... 0.62 0.13 0.75 0.05
November.. 2.87 2.00 2.80
December.. 1.35

Total 8.33 6.28 906 7.05 9.59 6.42 9.52 9.831295 Inches

N. of months drouths 5 3 3 4 7 6 5 7 8
Average of months of drouth, 5.33

The cost of pumping water as determined at the Ewa Plantation
in Hawaii, where 64,750,000 gallons of water are pumped daily to an
average height of 91 feet, maximum 205 feet, using oil as fuel, at the
cost of $1.40 per barrel, four barrels of oil being equivalent to one
ton of coal, (which formerly cost $8.00 per ton) cost 5% cts. for

24

lifting 1,000,000 gallons one foot, adding to the above interest on the
plant and maintenance, the cost is increased to 8 cts. per million
gallons lifted 1 foot

It may be of interest to mention that Reidler Pumps have been
found the most satisfactory for pumping to high elevations, as the
valves in these pumps are automatically closed, there is less loss of
water from slip. They are usually driven by triple expansion con-
densing engines, steam being delivered at 225 ‘lbs. pressure from water
tube boilers, fitted with Gre‘n’s economizer or other good system of
feed water heater.

- As has been shown, elevating one million gallons of water one foot
costs 8 cts., thea to pump one million ga'lons to 100 feet elevation
will cost $8.00, 200 feet $16.00, to 300 feet $24.00.

By carefully conducted experiments made at the Hawaiian Expe-
riment Station, where the water used in irrigating was carefully
measured, it was found that the amount of water required to produce
22,974 lbs. of available sugar, equalled 4,751,950 gallons, and to pro-
duce 20,900 lbs. of available sugar from the same area, 1,656,394
gallons of water were required. That isto say, that by the application
of one inch of water per week only 2074 Ibs. of sugar less, were
produced, than where three inches of water were applied weekly.
It was also found that 8 inches of water applied per week gave the
maximum yield; but from the foregoing figures it is shown that the
most profitable amount of water to be applied between one and three
inches weekly will altogether depend onthe cost of water delivered
on the land.

In pumping water to the higher lands, these can stand a much
greater reduction in the amount of water used than at the lower levels,
and in taking water at a certain figure, say, from an irrrigating
company, the amount which can be profitably used may from the
foregoing figures be closely calculated.

Cane makes the most rapid growth during the hot months or
between May and November, where there is sufficient moisture in the
soil. The difference in temperature during this period in Arecibo is
about 4 degrees F. A saturation giving about 77% of the soil’s capacity
for water will give the best results. The maximum of water which can
be profitably used in Porto Rico will probably not exceed two inches
per week as against three inches in the Hawaiian Islands.

The average yield of sugar per acre will also fall off in about the
same proportion and will not be more than about + tons per acre as
against 6 tons average in Hawaii under the same growing period. And the
maximum yield under the most favorable conditions in Porto Rico will
not exceed 7 tons of sugar per acre as against 10 tons in Hawaii over
any large area. This is due to climatic differences and also because the
soilin Porto Rico contains more clay and is pot so well drained, and
consequently not so well aerated.

Rainfall is not to any extent affected by the removal of forests
but is governed largely by the topography of the country and the
direction of the prevailing winds.

In irrigating cane, water is conserved by having the cane rows
not more than 30 feet long, filling these one ata time from the lateral
ditch, then closing them off.

In making any permanent improvement, the cost, in its relation
to the income it will bring, should always be carefully estimated, so
the effectiveness of the different systems of delivering waters for

25

irrigation either from streams or wells should be carefully studied. If
pumps have to be used, their efficiency should be tested from time
to time, or if the water is delivered by canals the leakage or seepage
should be determined by measurement, as no good management can
be had where the losses are not knowa, and knowing where losses occur

is the first step towards preventing them. This is just as important
in the fields as in the factory.