THE IKEIGATION AGE. 



209 



THE PRIMER OF IRRIGATION. 



BY D. H. ANDERSON. 



COPYRIGHT. 1903, BY D. H. ANDERSON. 



CHAPTER II. 



PARTICULAR SOILS, AND THEIR ADAPTATION 

 VARIETIES OF PLANTS. 



TO 



Although this book is 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 irrig- 

 able lands, as successfully as those where a rain fall 

 may be depended upon to raise a crop. It is even pos- 

 sible that such information may be of greater practical 

 value, because the elements in the soil and the crop itself, 

 are under better control and management when the 

 ncessary 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 ele- 

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

 particularly when crops of a certain kind are to be suc- 

 cessfully raised. 



It was stated in the last chapter that soil consists of 

 inorganic and organic elements. The inorganic ma- 

 terial being decomposed rocks and minerals ; 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 veget- 

 able 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 car- 

 bon, hydrogen, oxygen, and nitrogen, are burned away 

 and disappear, but there remains behind an "ash" com- 

 posed of potash, soda, lime, magnesia, iron, etc., which 

 does not burn, and which, in most cases, does not under- 

 go 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 

 practical 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 

 happen if the organic food supplied the plant by the 

 vegetable 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 BODY 

 Chlorine. 

 Iodine 

 Sulphur 

 Sulphur 

 Sulphur 

 Phosphorus 

 Potassium 

 Potassium 

 Sodium 

 Sodium 



Calcium 



Calcium 



Magnesium 



Aluminum 



Silicon 



Iron and ) 



Manganese ) 



COMBINES WITH 



FORMING 



Metals Chlorides. 



Metals Iodides. 



Metals Sulphurets. 



Hydrogen Sulphuretted Hydrogen. 



Oxygen Sulphuric Acid. 



Oxygen Phosphoric Acid. 



Oxygen Potash. 



Chlorine Chloride of Potassium. 



Oxygen Soda. 



Chlorine Chloride of Sodium, 



Common salt. 



Chlorine Chloride of Calcium. 



Oxygen Lime. 



Oxygen Magnesia. 



Oxygen Alumina. 



Oxygen Silica. 



Oxygen < Oxides. 



Sulphur ( Sulphurets. 



or 



All the above elementary substances, except sul- 

 phur, exist only in a state of combination with other sub- 

 stances, principally oxygen, and are found only in the 

 soil, in no combination are they generally diffused 

 through the atmosphere, 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. 



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 ascer- 

 tain 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 ordi- 

 nary 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 mineral in an agreed one hundred parts, 

 and the third column the weight of each substance in 

 the surface soil eight inches deep : 



Elementary bodies and their combinations Percentage We'ght in pound 



Silica and fine sand 87.143 3,203,781+ 



Alumina 5.666 208,308+ 



Oxides of Iron 2.220 81,617+ 



Oxide of Magnesia 0.360 13,235+ 



Lime 0.564 20,735+ 



Magnesia 0.312 1 1,470+ 



