156 



THE IRRIGATION AGE. 



or no moisture at all from the clouds, and a soil parched, 

 even burned by the hot sun. Yet the scientists have dis- 

 covered and classified 197 different species of plants that love 

 the desert soil and flourish in it. Many of them suitable for 

 animal food, all of them indicating some quality in or under 

 the soil as plainly as if they were labeled. 



Thus, greasewood, or "creosote bush," indicates less than 

 0.4 per cent of alkali in the soil ; salt grass and foxtail mean 

 that there is plenty of moisture at the surface of the ground 

 and consequently, the presence of free ground water not 

 far below the surface ; shad scale indicates dry land with 

 less than 0.4 per cent of salt ; rabbit bush flourishes on sandy 

 soil comparatively free from salts, and will seldom grow under 

 any other conditions ; sweet clover and foxtail indicate wet 

 land and less than four per cent of salts, though sweet clover 

 will grow in six per cent alkali soil and produce a fairly 

 good crop for forage if harvested very early. 



So it is with the color of the soil. Indications are ever 

 present of the dominant characteristics of the ground. Red 

 soils always indicate iron in the form of an oxide ; black 

 soils mean carbonate of soda, an alkali ruinous to vegetation ; 

 white soils or gray mean soda in sulphate salt form, also dele- 

 terious to plants when more than one or two per cent ; gray 

 or brown and black cracked or checked soil with vegetation, 

 signifies adobe, while barren, dark or light colored soil so 

 hard that dynamite is more suitable for its tillage than a plow, 

 is "hardpan" the former indicating a soil retentive of moisture, 

 the latter indicating that moisture is somewhere beneath. 



Another peculiarity of desert land soils is the frequent 

 occurrence in the soil when plowed or dug up, of innumerable 

 small roots or rooty fibers. They are, indeed, vegetable re- 

 mains, but through lack of moisture, they have not fermented 

 into humus, though it may be said that they have practically 

 "oxydized" without losing any of their nitrogenous elements. 

 It is well for the desert soil where this organic matter exists, 

 that these rooty fibers have not fermented, for the inorganic 

 matter, the alkalies and other mineral and metallic salts would 

 have speedily devoured the product and left nothing for 

 plants to feed upon. The reader has already been informed 

 that both organic and inorganic elements are essential to plant 

 life, and that the inorganic elements the substances given 

 in the table in the second chapter and their combinations 

 into salts, are largely in excess of the organic elements. The 

 same principle holds good in the case of desert soils it is 

 not a theory but a practical fact that organic matter added 

 to the inorganic means life ; their separation, death. Hence, 

 it is clear, that the addition or presence of organic matter 

 and nitrogen, added to the mass of inorganic substances in 

 the soil, tempers the latter and lessens its natural tendency 

 to do harm. In the case of an alkali soil, vegetable matter 

 and nitrogenous substances lessen the deleterious effects of 

 the alkali, although it may not reduce the percentage of the 

 salts. Whence, also, the presence of masses of coarse or 

 fine vegetable fibers in the soil is evidence of either the absence 

 of an excess of alkali, or that it is under control and innocuous 

 to vegetation. Perhaps the reader may see in this a way to 

 get rid of the alkali in soils and render them fertile. If he 

 does, he will not be far wrong in his idea, as we shall see 

 presently. 



Lack of Water. 



There are two conditions which are the bane of all 

 desert lands, whether arid or semi-arid : Lack of water and 

 the presence, in excess, of alkalis. We shall devote space 

 here to some general remarks on both conditions, leaving it 

 to subsequent chapters to enter more into details. The 

 chapters on "Alkali Soils," "The Relations of Water to 

 the Soil," and that on "Cultivation," will give more particulars, 

 though at this point it may be necessary to include matter 

 which will be repeated elsewhere, or presented from a differ- 

 ent viewpoint. This, however, should not be deprecated as 

 a fault, but extolled as a benefit, for the subject is of so much 

 vital importance that it can not be repeated too often, lest 

 it be forgotten. 



There must be a water table at some point below every 

 soil, at a less or greater depth. This may be accepted as a 

 fact without going into geology to prove it. Such subsoil 

 water originates in a variety of sources, through percolations 

 from above, underground streams coming from great dis- 

 tances, from springs that have their original sources in some 

 nearby hill or mountain land, by seepage from rivers, brooks, 

 or streams, from an irrigating ditch, or pond, and from the 

 artificial surface application, or through sub-irrigation. Al- 



though the action of the earths gravity pulls or draws water 

 downward as it does every other object heavier than the 

 atmosphere, the constant natural tendency of the water be- 

 neath the surface is to rise to the surface and evaporate. 



It is this rise of. the water table to the surface that 

 causes more alarm than any other process of nature in the 

 arid and semi-arid regions, particularly in the arid regions 

 where all water must be applied artificially. The reason is 

 obvious. The subsoil water contains in solution whatever 

 soluble salts it may come in contact with, and reaching the 

 surface, evaporates, leaving behind a deposit of the salts as 

 crystals. Constant deep cultivation also has a tendency to 

 bring up the water table with alkaline solutions, for we have 

 already seen that the subsoil contains in reserve as much 

 mineral matter and salts as the surface soil. And this is so 

 whether the land is in the arid regions or in the rain belt, 

 the disadvantage of the desert land being that the proportion 

 of organic matter is not high enough to maintain an equilib- 

 rium of plant food consumption. Still, this is not an incur- 

 able disadvantage, for when the labor and expense of drain- 

 ing, mixing, tempering, and reducing soils in the rain belt 

 is compared with the trifling care and attention devoted to 

 desert land soils to render them continuously fertile, the 

 wonder is that they produce any crops at all, so slight is the 

 effort to make them yield. 



Water Tables. 



It is not uncommon to fill the subsoil with water from 

 irrigating ditches, by putting into it all the supply obtainable 

 during the flood season, thus bringing the water table suffi- 

 ciently near the surface to supply the crops by capillary 

 action. This brings the ground water within three or four 

 feet of the surface, which is well enough for alfalfa and 

 gross feeding plants, but is bad for trees, vines, and more 

 delicate plants. In arid regions where irrigation is the 

 only means of bringing moisture to the soil the water 

 table may be a hundred or more feet below the surface 

 and cannot rise on account of impenetrable strata of 

 rock or hardpan. But in that case the irrigation water 

 creates a new water table, the excess of the irrigating 

 water sinking down until it meets an impervious stratum 

 of rock or hardpan, and there it accumulates, becomes 

 stationary, dissolves out the earth salts and when the surface 

 soil dries out or is deeply cultivated begins coming to the 

 surface by capillary action, every subsequent additional satura- 

 tion of the soil from the irrigating ditch increasing the area 

 and zone of the artificial water table. When that happens, 

 and it does happen in desert lands sooner than it takes to 

 clear the ground of trees and stumps in the rain belt, drainage 

 becomes of vital importance, second to irrigation itself. 



In semi-arid regions, where there is some rain fall, though 

 inadequate, the amount of rainfall, whatever it may be, has 

 washed the alkali out of the surface soil down into the water 

 table, and the surface soil is freer from the deleterious ma- 

 terial, which in the arid soils even prevents the seeds from 

 germinating and obta'ning a foothold strong enough to resis 

 it, for when a plant has outgrown its infancy, and develope 

 its first true leaves, it will require a most extraordinary 

 quantity of deleterious material to destroy it. It refuses to 

 absorb what it does not need and does not require, and unless 

 wholly overpowered by the solutions in the water that sur- 

 rounds it, it will grow up to be something more or less 

 perfect. 



It is said that six or eight inches of rain will mature a 

 crop in the semi-arid region with proper cultivation. It 

 matters little whether it be wheat or barley if the grain be 

 sown very thin to allow more room for stooling. Six inches 

 will grow it to fodder and eight inches will cause it to head 

 out fairly well. An instance has been called to the attention 

 of the author, where ten inches produced two crops without 

 irrigation. 



A fair crop of potatoes was grown in and removed from 

 the fibrous, red clayey soil in April. The land lay on a side 

 hill, about in the center, the summit of which had been roughly 

 plowed to gather as much rain as possible so as to utilize 

 the seepage for the potatoes. Immediately after the removal 

 of the potatoes the land was plowed deep, and moisture still 

 showing, it was carefully cutivated. Corn, of the variety 

 known as "white Mexican," was then d : bbled in and left 

 to its fate. From the time of its planting, until harvested, 

 not a drop of water was put on the land by way of irriga- 

 tion, and only about an inch of rain in "Scotch mists" fell 

 (Continued on page 181.) 



