124 



THE IRKIGATION AGE. 



land, has much to do with its heat. The more perpendic- 

 ular the rays, the greater the heat. The effect is less in 

 proportion as these rays, by falling more slanting, spread 

 their light out over a greater surface. This point is so 

 well understood that it is not necessary to dwell any 

 longer upon it, further than to add, that there are local- 

 ities where every degree of heat diminishes the prospect 

 of a good crop, particularly in hot regions, and the cir- 

 cumstances should be taken advantage of to obviate the 

 danger of loss. A northern exposure or an eastern ex- 

 posure, or a crop on a slope may sometimes realize more 

 benefit than if this knowledge were disregarded. 



Humus Absorbs Moisture. 



The relation of soil to moisture and gas, particularly 

 moisture, is of great importance in the case of irrigation. 

 All soil, except pure siliceous sand, absorbs moisture, but 

 in different degrees. Humus possesses the greatest powers 

 of absorption, and no variety of humus equals in its ab- 

 sorptive power, that from animal manure, except those 

 heavily charged arid and semi-arid lands, in which fibrous 

 roots and vegetable matter form a large part of the ele- 

 ments they contain. The others rank in the following 

 order: Garden mould, clay, loam, sandy clay, arable soil. 

 They all become saturated with moisture by a few days' 

 exposure. , 



It is a very interesting question. Does soil give up 

 this absorbed water speedily and equally? Is its power 

 of retaining water equal? There is no more important 

 question to the irrigator. As a general fact, it may be stated, 

 that the soil which absorbs fastest and most, evaporates slow- 

 est and least. Humus evaporates least in a given time. The 

 power of evaporation is modified by the consistency of the 

 soil; by a different degree of looseness and compactness of 

 soil. Garden mould, for instance, dries faster than clay. As 

 it has already been shown, that the power of being warmed 

 is much modified by moisture, so the power of a soil to re- 

 tain water makes the distinction of a hot or cold, wet or dry 

 soil. 



Connected with this power of absorbing moisture, is the 

 very important relation of soil to gas. All soils absorb 

 oxygen gas when damp, never when dry. Humus has this 

 power in the highest degree, however, whether it be wet or 

 dry. Clay comes next, frozen earths not at all. A moderate 

 temperature increases the absorption. Here are the conse- 

 quences of this absorptive power. 



When earths absorb oxygen, they give it up unchanged. 

 But when humus absorbs oxygen, one portion of that com- 

 bines with its carbon, producing carbonic acid, which decom- 

 poses silicates, and a second portion of the oxygen combines 

 with the hydrogen of the humus and produces water. Hence, 

 in a dry season well manured soils, or those abounding in 

 humus, suffer very little. 



The evaporation from an acre of fresh-ploughed land is 

 equal to 950 pounds per hour; this is the greatest for the 

 first and second days, ceases about the fifth day, and begins 

 again by hoeing, while, at the same time, the unbroken 

 ground affords no trace of moisture. This evaporation is 

 equal to that which follows after copious rains. These are 

 highly practical facts, and teach the necessity of frequent 

 stirring of the soil in the dry season. Where manure or 

 humus is lying in the soil, the evaporation from an acre 

 equals 5,000 pounds per hour. At 2,000 pounds of water per 

 hour, the evaporation would amount in 92 days, that is, a 

 growing season, to 2,208,000 pounds, an enormous quantity 

 of water, too much to be permitted, however beneficial that 

 evaporation may be. It is true that this evaporation is charged 

 with carbonic acid, and acts on the silicates, eliminates alkalies, 

 waters and feeds plants, but where irrigation is practiced, 

 the evaporation is carried on with as good an effect beneath 

 a mulch of finely pulverized soil through which it penetrates, 

 if the land is properly prepared for and tilled after the appli- 

 cation of water. This is a subject which demands careful 

 study, so that the laws of nature may be as rigorously en- 

 forced when man takes them under his control, otherwise, 

 there will always be failure. How to enforce those laws 



without doing violence to the principles which underlie them, 

 is matter which will be fully treated in future chapters. 



In concluding this chapter, it is deemed proper to call 

 the attention of the reader to this maxim which should never 

 be forgotten: It is not the plants grown in a soil that 

 exhaust it, but those removed from it. It is an undeniable 

 fact, that the growth of plants in any soil is beneficial, inas- 

 much as it brings into play the forces of nature which are 

 in constant motion toward increase through fertility. For 

 ages, the great prairies of the West, and also the so-called 

 "arid, and semi-arid" lands have been storing up humus which 

 now needs but the application of water to convert them into 

 lands that will laugh with rich harvests. Plant life has, for 

 centuries, sprung into existence, reached maturity, and de- 

 cayed, going back into the soil, with no hand to remove it. 

 The consequence is, all these lands are rich in salts and 

 humus, and it is left for the man with the ditch to add 

 moisture, open the soil and admit oxygen to the seeds he 

 plants, so that they shall be fed up to perfection and enable 

 him to reap a glorious harvest. 



The laws of nature are the same in this regard as to the 

 man who looks to the heavens for his inconstant rainfall. 

 There is for him to consider in the lands under ditch, that 

 all soil has four important functions to perform, which are: 



First. It upholds the plant, affording it a sure and safe 

 anchorage. 



Second. It absorbs water, air and heat to promote its 

 growth. These are the mechanical and physical functions 

 of the soil. 



Third. It contains and supplies to the plant both organic 

 and inorganic food as its wants require; and 



Fourth. It is a workshop in which, by the aid of air 

 and moisture, chemical changes are continually going on; by 

 which changes these several kinds of foods are prepared for 

 admission into the living roots. 



These are its chemical functions. They all are the law 

 and the gospel of agriculture, and all the operations of the 

 farmer are intended to aid the soil in the performance of one 

 or the other of these functions. 



ILLINOIS HONORS McCORMICK. 



Agricultural College Admits Name of Inventor of Har- 

 vester to Hall of Fame. 



In recognition of his services as a contributor to the 

 agricultural development of the country, through his in- 

 vention and the perfecting of the harvesting machine, the 

 Illinois College of Agriculture has admitted the name and 

 portrait of Cyrus Hall McCormick to the hall of fame. 

 There were many impressive features to the ceremonies 

 on December 15 and among those gathered at Urbana to 

 participate were the foremost statesmen and business men 

 of Illinois. 



That the event received recognition from the many 

 workers in fields of scientifice agriculture was indicated 

 by the numerous letters received from foreign ministers 

 of agriculture. These letters will be incorporated in 

 memorial column to be kept at the College of Agriculture. 



In speaking of Mr. McCormick, President A. P. Grout. 

 of the Farmers' Hall of Fame Commission, said: 



"This gathering, these exercises, mark an important 

 epoch. It is the first recognition of the services of the 

 men who have contributed largely to the growth of the 

 country. To no one is the country more indebted in this 

 respect than to Cyrus Hall McCormick. Farming has 

 been transformed from laborious drudgery to a scientific 

 industry. 



"No invention probably contributed so much to this 

 changed condition as the reaper. More effective means 

 of harvesting called for a more scientific way of sowing. 

 Mr. McCormick lived to see his invention recognized by 

 all of the great nations of the globe." 



Send $2.50 for The Irrigation Age, one year, and 

 the Primer of Irrigation, a 260-page finely illustrated 

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