THE IRRIGATION AGE. 



301 



dered by the people of Ogden and Utah, which alone 

 presents sights well worth traveling across the continent 

 to see. 



THE PRIMER OF IRRIGATION. 



BY D. H. ANDERSON. 



COPYRIGHTED, 1903, BY D. H. ANDERSON. 



CHAPTER V. 



RELATIONS OF WATER TO THE SOIL. 



When a small portion of soil is thoroughly dried 

 and then spread out on a sheet of paper in the open air 

 it will gradually drink in watery vapor from the atmos- 

 phere and thus increase its weight to a perceptible de- 

 gree. In hot climates and during dry seasons this prop- 

 erty of absorption in the soil is of great importance re- 



ing quantity of water when the weight of it on an acre 

 of ground is calculated. The weight of dry and wet 

 soils has already been given, and the difference between 

 the two will, of course, show the quantity in weight of 

 the moisture or water absorbed. The average weight 

 of dry soils is about 94 pounds, the average ordinary 

 wet weight is 126 pounds, the difference, being 32 

 pounds, represents the average weight of water per cubic 

 foot. Now, multiplying 43,560 square feet in the acre 

 by 32, gives 1,393,920 pounds to the acre one foot deep, 

 and dividing by 12 to ascertain the weight of one inch, 

 we have 116,160 pounds, or about 58 tons of water 

 falling on an acre of ground in the shape of dew in a 

 single night. Of course that quantity represents the 

 highest possible absorptive quality in a heavily charged 

 vegetable soil. Other soils would receive a less quantity 

 as will be readily understood, but there is enough to 



2'. The Idan-ha. 

 28. The Brown. 



THE HOTELS IN OGDEN, UTAH. 

 27. The Reed. 



28. The Healy. 



29. The European. 



storing, as it does, to the thirsty ground, and bringing 

 within reach of plants, a part of the moisture they 

 have so copiously exhaled during the day. Different 

 soils possess this property in unequal degrees. During a 

 night of twelve hours, for it is at night that watery vapor 

 is deposited on the ground (evaporation from the soil 

 occurring during the day), 1,000 pounds of perfectly 

 dry soil will absorb the following quantities of moisture 

 in pounds. 



Quartz sand 



Calcareous sand 2 



Loamy soil 21 



Clay loams 25 



Pure clay 27 



Peaty soils and those rich in vegetable matters will 

 absorb a much larger quantity from the atmosphere, 

 sometimes becoming "wet" two inches deep, a snrpris- 



be equivalent to quite a smart shower and worth en- 

 couraging. 



In what are known as "dry" climates there is 

 always some moisture in the atmosphere which is de- 

 posited upon the soil, for wherever there are oxygen 

 and hydrogen there must be moisture. But the quan- 

 tities vary in climates as much as they do in soils. 

 Where there is evaporation from the soil moisture dur- 

 ing the day there is also a re-absorption of moisture by 

 the soil at night and, with this fact in mind, it may be 

 laid down as an axiom: The tendency of water is to 

 evaporate from the soil into the atmosphere during the 

 day and to fall back upon the soil during the night. To 

 reduce the idea to an axiom : A dry soil has an affinity 

 for a moist atmosphere, and a dry atmosphere loves a 

 moist soil. 



SATURATION AND POWER TO RETAIN MOISTURE. 



The rain falls and is_drunk in by the thirsty soil; 



