CHAPTER XVI
IRRIGATION AND DRY-FARMING
IRRIGATION-farming and dry-farming are both systems
of agriculture devised for the reclamation of countries that ordinarily receive an
annual rainfall of twenty inches or less. Irrigation-farming cannot of itself reclaim
the arid regions of the world, for the available water supply of arid countries when
it shall have been conserved in the best possible way cannot be made to irrigate
more than one fifth of the thirsty land. This means that under the highest possible
development of irrigation, at least in the United States, there will be five or six
acres of unirrigated or dry-farm land for every acre of irrigated land. Irrigation
development cannot possibly, therefore, render the dry-farm movement valueless. On
the other hand, dry-farming is furthered by the development of irrigation farming,
for both these systems of agriculture are characterized by advantages that make irrigation
and dry-farming supplementary to each other in the successful development of any
arid region.
Under irrigation, smaller areas need to be cultivated
for the same crop returns, for it has been amply demonstrated that the acre yields
under proper irrigation are very much larger than the best yields under the most
careful system of dry-farming. Secondly, a greater variety of crops may be grown
on the irrigated farm than on the dry-farm. As has already been shown in this volume,
only certain drouth resistant crops can be grown profitably upon dry-farms, and these
must be grown under the methods of extensive farming. The longer growing crops, including
trees, succulent vegetables, and a variety of small fruits, have not as yet been
made to yield profitably under arid conditions without the artificial application
of water. Further, the irrigation-farmer is not largely dependent upon the weather
and, therefore, carries on this work with a feeling of greater security. Of course,
it is true that the dry years affect the flow of water in the canals and that the
frequent breaking of dams and canal walls leaves the farmer helpless in the face
of the blistering heat. Yet, all in all, a greater feeling of security is possessed
by the irrigation farmer than by the dry-farmer.
Most important, however, are the temperamental
differences in men which make some desirous of giving themselves to the cultivation
of a small area of irrigated land under intensive conditions and others to dry-farming
under extensive conditions. In fact, it is being observed in the arid region that
men, because of their temperamental differences, are gradually separating into the
two classes of irrigation-farmers and dry-farmers. The dry-farms of necessity cover
much larger areas than the irrigated farms. The land is cheaper and the crops are
smaller. The methods to be applied are those of extensive farming. The profits on
the investment also appear to be somewhat larger. The very necessity of pitting intellect
against the fierceness of the drouth appears to have attracted many- men to the dry-farms.
Gradually the certainty of producing crops on dry-farms from season to season is
becoming established, and the essential difference between the two kinds of farming
in the arid districts will then he the difference between intensive and extensive
methods of culture. Men will be attracted to one or other of these systems of agriculture
according to their personal inclinations.
The scarcity of water
For the development of a well-rounded commonwealth
in an arid region it is, of course) indispensable that irrigation be practiced, for
dry-farming of itself will find it difficult to build up populous cities and to supply
the great variety of crops demanded by the modern family. In fact, one of the great
problems before those engaged in the development of dry-farming at present is the
development of homesteads in the dry-farms. A homestead is possible only where there
is a sufficient amount of free water available for household and stock purposes.
In the portion of the dry-farm territory where the rainfall approximates twenty inches,
this problem is not so very difficult, since ground water may be reached easily.
In the drier portions, however, where the rainfall is between ten and fifteen inches,
the problem is much more important. The conditions that bring the district under
the dry-farm designation imply a scarcity of water. On few dry-farms is water available
for the needs of the household and the barns. In the Rocky Mountain states numerous
dry-farms have been developed from seven to fifteen miles from the nearest source
of water, and the main expense of developing these farms has been the hauling of
water to the farms to supply the needs of the men and beasts at work on them. Naturally,
it is impossible to establish homesteads on the dry-farms unless at least a small
supply of water is available; and dry-farming will never he what it might be unless
happy homes can be established upon the farms in the arid regions that grow crops
without irrigation. To make a dry-farm homestead possible enough water must be available,
first of all, to supply the culinary needs of the household. This of itself is not
large and, as will be shown hereafter, may in most cases be obtained. However, in
order that the family may possess proper comforts, there should be around the homestead
trees, and shrubs, and grasses, and the family garden. To secure these things a certain
amount of irrigation water is required. It may be added that dry-farms on which such
homesteads are found as a result of the existence of a small supply of irrigation
water are much more valuable, in case of sale, than equally good farms without the
possibility of maintaining homesteads. Moreover, the distinct value of irrigation
in producing a large acre yield makes it desirable for the farmer to use all the
water at his disposal for irrigation purposes. No available water should be allowed
to flow away unused.
Available surface water
The sources of water for dry-farms fall readily
into classes: surface waters and subterranean waters. The surface waters, wherever
they may be obtained, are generally the most profitable. The simplest method of obtaining
water in an irrigated region is from some irrigation canal. In certain districts
of the intermountain region where the dry farms lie above the irrigation canals and
the irrigated lands below, it is comparatively easy for the farmers to secure a small
but sufficient amount of water from the canal by the use of some pumping device that
will force the water through the pipes to the homestead. The dry-farm area that may
be so supplied by irrigation canals is, however, very limited and is not to be considered
seriously in connection with the problem.
A much more important method, especially in the
mountainous districts, is the utilization of the springs that occur in great numbers
over the whole dry-farm territory. Sometimes these springs are very small indeed,
and often, after development by tunneling into the side of the hill, yield only a
trifling flow. Yet, when this water is piped to the homestead and allowed to accumulate
in small reservoirs or cisterns, it may be amply sufficient for the needs of the
family and the live stock, besides having a surplus for the maintenance of the lawn,
the shade trees, and the family garden. Many dry-farmers in the intermountain country
have piped water seven or eight miles from small springs that were considered practically
worthless and thereby have formed the foundations for small village communities.
Of perhaps equal importance with the utilization
of the naturally occurring springs is the proper conservation of the flood waters.
As has been stated before, arid conditions allow a very large loss of the natural
precipitation as run-off. The numerous gullies that characterize so many parts of
the dry-farm territory are evidences of the number and vigor of the flood waters.
The construction of small reservoirs in proper places for the purpose of catching
the flood waters will usually enable the farmer to supply himself with all the water
needed for the homestead. Such reservoirs may already be found in great numbers scattered
over the whole western America. As dry-farming increases their numbers will also
increase.
When neither canals, nor springs, nor flood waters
are available for the supply of water, it is yet possible to obtain a limited supply
by so arranging the roof gutters on the farm buildings that all the water that falls
on the roofs is conducted through the spouts into carefully protected cisterns or
reservoirs. A house thirty by thirty feet, the roof of which is so constructed that
all that water that falls upon it is carried into a cistern will yield annually under
a a rainfall of fifteen inches a maximum amount of water equivalent to about 8800
gallons. Allowing for the unavoidable waste due to evaporation, this will yield enough
to supply a household and some live stock with the necessary water. In extreme cases
this has been found to be a very satisfactory practice, though it is the one to be
resorted to only in case no other method is available.
It is indispensable that some reservoir be provided
to hold the surface water that may be obtained until the time it may be needed. The
water coming constantly from a spring in summer should be applied to crops only at
certain definite seasons of the year. The flood waters usually come at a time when
plant growth is not active and irrigation is not needed.
The rainfall also in many districts comes most
largely at seasons of no or little plant growth. Reservoirs must, therefore, be provided
for the storing of the water until the periods when it is demanded by crops. Cement-lined
cisterns are quite common, and in many places cement reservoirs have been found profitable.
In other places the occurrence of impervious clay has made possible the establishment
and construction of cheap reservoirs. The skillful and permanent construction of
reservoirs is a very important subject. Reservoir building should be undertaken only
after a careful study of the prevailing conditions and under the advice of the state
or government officials having such work in charge. In general, the first cost of
small reservoirs is usually somewhat high, but in view of their permanent service
and the value of the water to the dry-farm they pay a very handsome interest on the
investment. It is always a mistake for the dry-farmer to postpone the construction
of a reservoir for the storing of the small quantities of water that he may possess,
in order to save a little money. Perhaps the greatest objection to the use of the
reservoirs is not their relatively high cost, but the fact that since they are usually
small and the water shallow, too large a proportion of the water, even under favorable
conditions, is lost by evaporation. It is ordinarily assumed that one half of the
water stored in small reservoirs throughout the year is lost by direct evaporation.
Available subterranean water
Where surface waters are not readily available,
the subterranean water is of first importance. It is generally known that, underlying
the earth's surface at various depths, there is a large quantity of free water. Those
living in humid climates often overestimate the amount of water so held in the earth's
crust, and it is probably true that those living in arid regions underestimate the
quantity of water so found. The fact of the matter seems to be that free water is
found everywhere under the earth's surface. Those familiar with the arid West have
frequently been surprised by the frequency with which water has been found at comparatively
shallow depths in the most desert locations. Various estimates have been made as
to the quantity of underlying water. The latest calculation and perhaps the most
reliable is that made by Fuller, who, after a careful analysis of the factors involved,
concludes that the total free water held in the earth's crust is equivalent to a
uniform sheet of water over the entire surface of the earth ninety-six feet in depth.
A quantity of water thus held would be equivalent to about one hundredth part of
the whole volume of the ocean. Even though the thickness of the water sheet under
arid soils is only half this figure there is an amount, if it could be reached, that
would make possible the establishment of homesteads over the whole dry-farm territory.
One of the main efforts of the day is the determination of the occurrence of the
subterranean waters in the dry-farm territory.
Ordinary dug wells frequently reach water at
comparatively shallow depths. Over the cultivated Utah deserts water is often found
at a depth of twenty-five or thirty feet, though many wells dug to a depth of one
hundred and seventy-five and two hundred feet have failed to reach water. It may
be remarked in this connection that even where the distance to the water is small,
the piped well has been found to be superior to the dug well. Usually, water is obtained
in the dry-farm territory by driving pipes to comparatively great depths, ranging
from one hundred feet to over one thousand feet. At such depths water is nearly always
found. Often the geological conditions are such as to force the water up above the
surface as artesian wells, though more often the pressure is simply sufficient to
bring the water within easy pumping distance of the surface. In connection with this
subject it must be said that many of the subterranean waters of the dry-farm territory
are of a saline character. The amount of substances held in solution varies largely,
but frequently is far above the limits of safety for the use of man or beast or plants.
The dry-farmer who secures a well of this type should, therefore, be careful to have
a proper examination made of the constituents of the water before ordinary use is
made of it.
Now, as has been said, the utilization of the
subterranean waters of the land is one of the living problems of dry-farming. The
tracing out of this layer of water is very difficult to accomplish and cannot be
done by individuals. It is a work that properly belongs to the state and national
government. The state of Utah, which was the pioneer in appropriating money for dry-farm
experiments, also led the way in appropriating money for the securing of water for
the dry-farms from subterranean sources. The world has been progressing in Utah since
1905, and water has been secured in the most unpromising localities. The most remarkable
instance is perhaps the finding of water at a depth of about five hundred and fifty
feet in the unusually dry Dog Valley located some fifteen miles west of Nephi.
Pumping water
The use of small quantities of water on the dry-farms
carries with it, in most cases, the use of small pumping plants to store and to distribute
the water properly. Especially, whenever subterranean sources of water are used and
the water pressure is not sufficient to throw the water above the ground, pumping
must be resorted to. The pumping of water for agricultural purposes is not at all
new. According to Fortier, two hundred thousand acres of land are irrigated with
water pumped from driven wells in the state of California alone. Seven hundred and
fifty thousand acres are irrigated by pumping in the United States, and Mead states
that there are thirteen million acres of land in India which are irrigated by water
pumped from subterranean sources. The dry-farmer has a choice among several sources
of power for the operation of his pumping plant. In localities where winds are frequent
and of sufficient strength windmills furnish cheap and effective power, especially
where the lift is not very great. The gasoline engine is in a state of considerable
perfection and may be used economically where the price of gasoline is reasonable.
Engines using crude oil may be most desirable in the localities where oil wells have
been found. As the manufacture of alcohol from the waste products of the farms becomes
established, the alcohol-burning engine could become a very important one. Over nearly
the whole of the dry-farm territory coal is found in large quantities, and the steam
engine fed by coal is an important factor in the pumping of water for irrigation
purposes. Further, in the mountainous part of the dry-farm territory water Power
is very abundant. Only the smallest fraction of it has as yet been harnessed for
the generation of the electric current. As electric generation increases, it should
be comparatively easy for the farmer to secure sufficient electric power to run the
pump. This has already become an established practice in districts where electric
power is available.
During the last few years considerable work has
been done to determine the feasibility of raising water for irrigation by pumping.
Fortier reports that successful results have been obtained in Colorado, Wyoming,
and Montana. He declares that a good type of windmill located in a district where
the average wind movement is ten miles per hour can lift enough water twenty feet
to irrigate five acres of land. Wherever the water is near the surface this should
be easy of accomplishment. Vernon, Lovett, and Scott, who worked under New Mexico
conditions, have reported that crops can be produced profitably by the use of water
raised to the surface for irrigation. Fleming and Stoneking, who conducted very careful
experiments on the subject in New Mexico, found that the cost of raising through
one foot a quantity of water corresponding to a depth of one foot over one acre of
land varied from a cent and an eighth to nearly twenty-nine cents, with an average
of a little more than ten cents. This means that the cost of raising enough water
to cover one acre to a depth of one foot through a distance of forty feet would average
$4.36. This includes not only the cost of the fuel and supervision of the pump but
the actual deterioration of the plant. Smith investigated the same problem under
Arizona conditions and found that it cost approximately seventeen cents to raise
one acre foot of water to a height of one foot. A very elaborate investigation of
this nature was conducted in California by Le Conte and Tait. They studied a large
number of pumping plants in actual operation under California conditions, and determined
that the total cost of raising one acre foot of water one foot was, for gasoline
power, four cents and upward;. for electric power, seven to sixteen cents, and for
steam, four cents and upward. Mead has reported observations on seventy-two windmills
near Garden City, Kansas, which irrigated from one fourth to seven acres each at
a cost of seventy-five cents to $6 per acre. All in all, these results justify the
belief that water may be raised profitably by pumping for the purpose of irrigating
crops. When the very great value of a little water on a dry-farm is considered, the
figures here given do not seem at all excessive. It must be remarked again that a
reservoir of some sort is practically indispensable in connection with a pumping
plant if the irrigation water is to be used in the best way.
The use of small quantities of water in irrigation
Now, it is undoubtedly true that the acre cost
of water on dry-farms, where pumping plants or similar devices must be used with
expensive reservoirs, is much higher than when water is obtained from gravity canals.
It is, therefore, important that the costly water so obtained be used in the most
economical manner. This is doubly important in view of the fact that the water supply
obtained on dry-farms is always small and insufficient for all that the farmer would
like to do. Indeed, the profit in storing and pumping water rests largely upon the
economical application of water to crops. This necessitates the statement of one
of the first principles of scientific irrigation practices, namely, that the yield
of a crop under irrigation is not proportional to the amount of water applied in
the form of irrigation water. In other words, the water stored in the soil by the
natural precipitation and the water that falls during the spring and summer can either
mature a small crop or bring a crop near maturity. A small amount of water added
in the form of irrigation water at the right time will usually complete the work
and produce a well-matured crop of large yield. Irrigation should only be supplemented
to the natural precipitation. As more irrigation water is added, the increase in
yield becomes smaller in proportion to the amount of water employed. This is clearly
shown by the following table, which is taken from some of the irrigation experiments
carried on at the Utah Station:--
Effect of Varying Irrigations on Crop Yields Per Acre
| Depth of Water Applied (Inches) |
Wheat
(Bushels) |
Corn
(Bushels) |
Alfalfa
(Pounds) |
Potatoes
(Bushels) |
Sugar Beets
(Tons) |
| 5.0 |
40 |
|
|
194 |
25 |
| 7.5 |
41 |
65 |
|
|
|
| 10.0 |
41 |
80 |
|
213 |
26 |
| 15.0 |
46 |
78 |
|
253 |
27 |
| 25.0 |
49 |
77 |
10,056 |
258 |
|
| 35.0 |
55 |
|
9,142 |
291 |
26 |
| 50 |
60 |
84 |
13,061 |
|
|
The soil was a typical arid soil of great depth
and had been so cultivated as to contain a large quantity of the natural precipitation.
The first five inches of water added to the precipitation already stored in the soil
produced forty bushels of wheat. Doubling this amount of irrigation water produced
only forty-one bushels of wheat. Even with an irrigation of fifty inches, or ten
times that which produced forty bushels, only sixty bushels of wheat, or an increase
of one half, were produced. A similar variation may be observed in the case of the
other crops. The first lesson to be drawn from this important principle of irrigation
is that if the soil be so treated as to contain at planting time the largest proportion
of the natural precipitation,--that is, if the ordinary methods of dry-farming be
employed,--crops will be produced with a very small amount of irrigation water. Secondly,
it follows that it would be a great deal better for the farmer who raises wheat,
for instance) to cover ten acres of land with water to a depth of five inches than
to cover one acre to a depth of fifty inches, for in the former case four hundred
bushels and in the second sixty bushels of wheat would be produced. The farmer who
desires to utilize in the most economical manner the small amount of water at his
disposal must prepare the land according to dry-farm methods and then must spread
the water at his disposal over a larger area of land. The land must be plowed in
the fall if the conditions permit, and fallowing should be practiced wherever possible.
If the farmer does not wish to fallow his family garden he can achieve equally good
results by planting the rows twice as far apart as is ordinarily the case and by
bringing the irrigation furrows near the rows of plants. Then, to make the best use
of the water, he must carefully cover the irrigation furrow with dry dirt immediately
after the water has been applied and keep the whole surface well stirred so that
evaporation will be reduced to a minimum. The beginning of irrigation wisdom is always
the storage of the natural precipitation. When that is done correctly, it is really
remarkable how far a small amount of irrigation water may be made to go.
Under conditions of water scarcity it is often
found profitable to carry water to the garden in cement or iron pipes so that no
water may be lost by seepage or evaporation during the conveyance of the water from
the reservoir to the garden. It is also often desirable to convey water to plants
through pipes laid under the ground, perforated at various intervals to allow the
water to escape and soak into the soil in the neighborhood of the plant roots. All
such refined methods of irrigation should be carefully investigated by the who wants
the largest results from his limited water supply. Though such methods may seem cumbersome
and expensive at first, yet they will be found, if properly arranged, to be almost
automatic in their operation and also very profitable.
Forbes has reported a most interesting experiment
dealing with the economical use of a small water supply under the long season and
intense water dissipating conditions of Arizona. The source of supply was a well,
90 feet deep. A 3 by 14-inch pump cylinder operated by a 12-foot geared windmill
lifted the water into a 5000-gallon storage reservoir standing on a support 18 feet
high. The water was conveyed from this reservoir through black iron pipes buried
1 or 2 feet from the trees to be watered. Small holes in the pipe 332 inch in diameter
allowed the water to escape at desirable intervals. This irrigation plant was under
expert observation for considerable time, and it was found to furnish sufficient
water for domestic use for one household, and irrigated in addition 61 olive trees,
2 cottonwoods, 8 pepper trees, 1 date palm, 19 pomegranates, 4 grapevines, 1 fig
tree, 9 eucalyptus trees, 1 ash, and 13 miscellancous, making a total of 87 useful
trees, mainly fruit-bearing, and 32 vines and bushes. (See Fig. 95.) If such a result
can be obtained with a windmill and with water ninety feet below the surface under
the arid conditions of Arizona, there should be little difficulty in securing sufficient
water over the larger portions of the dry-farm territory to make possible beautiful
homesteads.
The dry-farmer should carefully avoid the temptation
to decry irrigation practices. Irrigation and dry-farming of necessity must go hand
in hand in the development of the great arid regions of the world. Neither can well
stand alone in the building of great commonwealths on the deserts of the earth.