THE IRRIGATION AGE. 



Notes on Practical 

 Irrigation 



D. II. Anderson 



PARTICULAR SOILS, 



Their Adaptation to Varieties of Plants Functions of Or- 

 ganic and Inorganic Elements. 



Although these notes are intended to apply exclusively 

 to irrigation, that is, the artificial application of water 

 to lands deprived of a sufficient rain fall to raise a crop, 

 such as the arid and semi-arid lands, which constitute so 

 vast a portion of our western country, yet, as all arable 

 or fertile soils in whatever part of the world they may 

 be, must contain certain elements necessary to plant life, 

 an inquiry into the specific nature of soils will supply 

 whatever information may be needed to till irrigable 

 lands, as successfully as those where a rain fall may be 

 depended upon to raise a crop. It is even possible that 

 such information may be of greater practical value, be- 

 cause the elements in the soil and the crop itself, are under 

 better control and management when the necessary water 

 is in an irrigating ditch, than when it is in a cloud 

 beyond control. 



As a matter of fact, there is very little difference in 

 soils as such* wherever they may exist. All of them are 

 capable of producing some variety of plant life, unless 

 absolutely barren on account of the absence of plant 

 food, as the Desert of Sahara, for instance, or by reason 

 of an excess of the elements essential to plant life, as 

 our so-called "alkali lands." But, when it comes to the 

 comparative quantities of organic and inorganic elements 

 to be found in all soils, there is a vast difference, par- 

 ticularly when crops of a certain kind are to be successfully 

 raised. 



Soil Has Two Elements. 



It was stated in the last chapter that soil consists of 

 inorganic and organic elements. The inorganic material 

 being decomposed rocks and mineral; to be more precise, 

 such as were never endowed with life, and the organic 

 material consisting of decomposed vegetable matter, which 

 once possessed some form of life, both of which elements 

 are absolutely necessary to grow any kind of plant. 



A little experiment, which any one can perform, 

 will make this clear to the reader. When any vegetable 

 substance is heated to redness in the open air, no matter 

 whether it be a peach or a potato, a strawberry or a squash, 

 a handful of straw or a beautiful rose, the whole of the 

 so-called organic elements, which are carbon, hydrogen, 

 oxygen, and nitrogen, are burned away and disappear, but 

 there remains behind an "ash" composed of potash, soda, 

 lime, magnesia, iron, etc., which does not burn, and 

 which, in most cases, does not undergo any diminution 

 when exposed to a much greater heat. It is this "ash" 

 which constitutes the inorganic portion of plants. 



The predominance of certain of these substances, 

 which, it was stated in the last chapter, are absorbed 

 from the soil by the operation of plant life, is what en- 

 ables agriculturists to give certain names to various kinds 

 of soils, which names, however, are of very little prac- 



tical importance, except to enable a farmer to specify 

 which of them are best adapted to the varieties of plants 

 he desires to raise. 



So far as these inorganic substances are concerned, 

 they must exist in the soil in such quantities as easily to 

 yield to the plant, so much of each one as the kind of 

 plant specifically requires. If they be rare, the plant 

 sickens and dies just the same as does an animal when 

 deprived of its necessary food. The same thing will hap- 

 pen if the organic food supplied the plant by the veg- 

 etable matter in the soil be wholly withdrawn. It should 

 be noted, however, that a plant will sometimes substitute 

 one inorganic element for another, if it does not find 

 exactly what it requires, as soda for potash, the tendency 

 of every plant being to grow to perfection if it possibly 

 can do so. This matter will be treated at length in the 

 chapter on "Plant Foods." 



The following table of the essential inorganic ele- 

 ments found in soils will prove useful and well worth 

 study. The first column gives the scientific, technical 

 name of the elementary bodies; the second column the 

 elements or substances they combine with, and the third 

 column contains the result of the combinations, that is, 

 the various substances ready to form salts which enter 

 into the life of the plant. 



Elementary Combined 



Body With Forming 



Chlorine Metals. Chlorides. 



Iodine Metals Iodides. 



Sulphur Metals Sulphurets. 



Sulphur Hydrogen Sulphuretted Hydrogen. 



Sulphur Oxygen Sulphuric Acid. 



Phosphorus Oxygen Phosphoric Acid. 



Potassium Oxygen Potash. 



Potassium Chlorine Chloride of Potassium. 



Sodium Oxygen Soda. 



Sodium Chlorine Chloride of Sodium, or 



Common Salt. 



Calcium Chlorine Chloride of Calcium. 



Calcium Oxygen Lime. 



Magnesium Oxygen Magnesia. 



Aluminum Oxygen Alumina. 



Silicon Oxygen Silica. 

 Iron and ) Oxygen ( Oxides. 

 Manganese $ Sulphur ( Sulphurets. 



All the above elementary substances, except sulphur, 

 exist only in a state of combination with other substances, 

 principally oxygen, and are found only in the soil; in no 

 combination are they generally diffused through the at- 

 mosphere, so as to be capable of entering into the life of 

 the plant through the leaves, or those portions above the 

 ground. Hence, they must be taken up by the roots of 

 plants, for which reason they are said to be the necessary 

 constituents of a soil in which plants are expected to 

 grow. 



Inorganic Matter in Soil. 



The enormous quantity of inorganic matter in soil 

 may be estimated by a simple calculation. Out of five 

 hundred samples of soil gathered from different parts of 

 the world, the average weight of a cubic foot, wet, has 

 been found to be 126.6 pounds. Now, let us ascertain how 

 many pounds of mineral, or metallic salts exist in an acre 

 of soil, say eight inches deep, the usual tilled depth, or 

 surface soil; of the subsoil, we shall speak later on. We 

 shall give the chemical analysis of an ordinary alluvial, 

 or river bottom soil, such as is common in the western 

 lands. The first column gives the name of the mineral, 

 and the figures in the second column the parts of the min- 

 eral in an agreed one hundred parts, and the third column 



