750 



THE IRRIGATION AGE. 



quent the surface, they are liable to suffer from drought, or 

 surface dryness. In this the reader will find an argument in 

 favor of sub-irrigation. 



Upon this instict of roots to seek their proper food in 

 moist soil, depends the measurement of soil tillage, whether 

 deep or shallow, and by "shallow" is not meant a mere sur- 

 face scratching, but a good wholesome upheaval of the soil 

 from a depth of eight to twelve inches, thence on up to 

 eighteen if the subsoil be in question. Where the subsoil is 

 not hard packed, then as deep as the subsoil; if packed it 

 should be broken up. But where the subsoil is open and 

 porous there is less need of deep plowing; on the contrary, 

 it may be necessary to pack the bottom of the furrow, which 

 is accomplished by a plow attachment known as a "packer," 

 so arranged as to follow the plow and press down the earth 

 at the bottom of the furrow; a useful contrivance where irri- 

 gation is practiced, inasmuch as it tends to prevent the 

 leaching of the irrigation water down into the porous subsoil, 

 where the water is run into the furrows. 



It can not be too strongly impressed upon the reader 

 that the soil must be so cultivated that it will retain moisture 

 without permitting it to leach beyond the reach of the roots, 

 and at trie same time so broken up and pulverized that the 

 roots may easily penetrate. Let this be the axiom constantly 

 in mind : Give the plant roots room to spread. Upon this 

 depends the perfection of the plant. "Stunts" are always 

 caused by too little root room, the plant languishing because 

 they are unable to reach moisture by reason of obstacles in the 

 soil. If there is any moisture in the soil the plant will get 

 it if it be given an opportunity. 



Let us assume that we have a parcel of land in which 

 it is purposed to grow plants without the application of ma- 

 nure. It does not matter whether it be virgin soil or one 

 that has already grown a crop of any kind; the first thing to 

 be done to this land is to improve the soil, that is, prepare it 

 for vegetation. This may be done in seven ways : 



First By cultivation, or, more properly speaking, pul- 

 verization of the soil, by plowing and other mechanical means 

 of reducing its consistency. 



Second -By mechanical consolidation. 



Third By exposure to the atmosphere ; that is, "fallow- 

 ing." 



Fourth By alteration of its constituent parts. 



Fifth By changing its condition in respect to water. 



Sixth By changing its position in respect to atmospheric 

 influences. 



Seventh By a change in the kinds of plants cultivated, 

 or "rotation of crops." 



Plowing and Pulverizing. 



All these different methods of preparing the soil means 

 practically the same thing the breaking up of the soil, whxh 

 must be done constantly if a good crop in quantity and quality 

 be desirable. 



By reason of their chemical elements the tendency of all 

 soils is to concrete ; that is, to run together in a sort of more 

 or less hard cement, a tendency enhanced by the growing of 

 crops and the application of water, or either. Thus, sand 

 without consistency and quicklime without coherence, when 

 mixed together with water, produce a hard cement or plaster, 

 which may be crushed and pulverized before it can become 

 again manageable. In soil the chemical agencies of nature 

 are constantly at work to produce the same result; hence 

 cultivation to break up, a tendency which is adverse to the 

 growth of plants and free root penetration. 



The very first objection of cultivation is to give scope to 

 the roots of plants to spread in every direction, for without 

 abundance of roots no plant can become vigorous, whatever 

 may be the richness of the soil in which it is placed. The 

 quantity of food taken from the soil does not depend alone 

 upon the quantity in the soil, but on the number of absorbing 

 root fibres. The more the soil is pulverized the more the fibres 

 are increased, the more food is obtained, and the more vig- 

 orous the plant becomes. Any house plant growing in an 

 earthenware pot will demonstrate this. The roots grown 

 down and then, finding an obstruction, begin growing round 

 and round in search of food, until the entire pot is filled with 

 root fibres, even forcing out the soil to find room, and when 

 they have grown to the limit of their confined space, the plant 

 stops growing and becomes sickly. 



Stirring Soil is Beneficial. 



This cultivation or stirring up of the soil for root ex- 

 pansion is not only essentially precious to plant, or sowing. 



but highly beneficial afterward, during the progress of vege- 

 tation; and when practiced in the spaces between the plants it 

 also operates as a method of root-pruning, by which the ex- 

 tended fibres are cut off, or shortened, thereby causing them 

 to throw out numerous other fibres whereby the mouths or 

 pores of the plants are greatly increased, and their food ca- 

 pacity enhanced. It is very much like fattening animals for 

 market by encouraging their consumption of fattening food. 



Cultivation renders capillary attraction more uniform, 

 this peculiarity of the soil being greater when the particles 

 of earth are finely divided. Thus, gravels and sands scarcely 

 retain water at all, while clays, not opened by pulverizaton 

 or other means of breaking them up, either do not readily ab- 

 sorb water, or when exposed to long action, they retain too 

 much of it. In the arid regions deep cultivation is essential 

 to admit moisture from the atmosphere, as for example, the 

 dews of night. In irrigated sections deep and thorough culti- 

 vation checks evaporation and reduces the accumulation of 

 alkali salts to a minimum, besides saving water. 



Heat is tempered by deep cultivation, which is a great 

 desideratum in the arid and semi-arid regions, the layer of 

 pulverized soil serving the purpose of shade or mulch, and 

 the evaporation retarded, the moisture acquires a uniform 

 temperature. This seems to be a small matter in plant 

 growth, but practical experience has demonstrated that it is 

 an important part of the general combination of practices 

 which result in successful agriculture. 



Whenever the soil is opened, turned over and otherwise 

 prepared for planting, a portion of the atmospheric air is 

 buried in the soil and this air so confined, is decomposed by 

 the moisture retained in the earthy matters. Ammonia is 

 formed by the union of the hydrogen of the water with the 

 nitrogen of the atmosphere, and nitre by the union of oxygen 

 and nitrogen. So, also, the oxygen of the air may unite 

 with the carbon contained in the soil and from carbonic acid 

 gas. Heat is given out during all these chemical processes. 

 As a rule farmers do not pay much attention to these simple 

 facts, but the plants he is growing do, and they are more or 

 less benefited as they are permitted to take advantage of these 

 laws of nature, or prevented. 



The depth of cultivation must depend upon the nature 

 of the soil and the variety of plant grown in it. The subsoil, 

 also, is not to be disregarded. Rich clayey soils can hardly 

 be cultivated too deep, and even in sands, unless the subsoil 

 contains alkali in dangerous quantities, or other plant poisons, 

 deep cultivation should be practiced. When the roots are deep 

 they are less liable to be injured by excessive water or 

 drought; the., radicals are shot forth in every part of the 

 soil, the spate from which nourishment is to be drawn being 

 extended over a much greater extent than when the seed is 

 superficially inserted in the soil. 



Soil Must be Thoroughly Mixed. 



In this respect cultivation should be attended with a 

 thorough mixture of the soil by turning it over and over. 

 Plowing, of course, accomplishes this result in a great meas- 

 ure, but the difference of gravity between the organic and the 

 inorganic matters in the earth, has a tendency to separate 

 them, for which reason light or shallow stirring of the soil is 

 of little or no use practically, because it leaves the surface of 

 the soil too light and spongy and the lower part too compact 

 and earthy. Even where the plant roots are near the surface 

 cultivation with a plow and a complete turning over of the 

 soil is much better than the mere scratching of the surface, 

 for there, as has been said, it is equivalent to root pruning. 



In a former chapter reference is made to the fact that 

 plant roots consume all the food in their neighborhood, and 

 this furnishes another obvious reason for deep cultivation, 

 otherwise the roots of a new crop reaching out for nourish- 

 ment find an empty cupboard. 



Some soils, however, require the opposite of pulverization 

 and demand mechanical consolidation. This will be under- 

 stood in the case of spongy peats and light, dusty sands. A 

 proper degree of adhesiveness is best given loose soils by the 

 addition of earthly matters in which they are deficient, per- 

 haps th bringing up of a heavier and more consistent subsoil 

 will accomplish the purpose. Rolling and treading, however, 

 are simple methods, but in that case the soil must be dry, 

 and the operation must not be carried too far, or so far as to 

 concrete the earth, which is its constant tendency, as has been 

 observed. 



A peat bog drained and rolled will sooner become covered 

 with grass than one equally well drained but left to itself. 

 Drifting sands, however, may well be rolled when wet, and 





