THE IRRIGATION AGE. 



333 



THE PRIMER OF IRRIGATION. 



COPYRIGHTED, 1903, BY D. H. ANDERSON. 



CHAPTER XVII. 



QUANTITY OF WATER TO RAISE CROPS. 



(The Duty of Water.) 



The amount of transpiration through the leaves of 

 plants will furnish an approximation of the quantity 

 of water needed by them before they can attain perfect 

 maturity. That amount of water in the shape of 

 moisture they must have, and if they can not obtain it 

 by natural means, through rainfall, ground water, 

 capillary action, dew, or moisture from the atmosphere, 



quantity required per acre during the growing period 

 of a crop, which is estimated at about 80 or 90 days. 



It is well for the reader to grasp the immensity of 

 such volumes of water, and to enable him to do so, a 

 few mathematical facts will not be out of place. 



One inch of water covering an acre of ground, 

 equals 27,154 gallons, or 1,086,160 gallons per acre for 

 the season upon the basis of a supposed total of forty 

 inches. The weight of this amount of water at 8 1-3 

 pounds standard II. S. weight to the gallon, is 

 nearly 4,526 tons. Weight will be used instead of 

 measure in order to make comparisons. 



Let us take potatoes as an illustration, and on them 

 base a simple calculation. According to the laws of 

 most of the States, a bushel of potatoes weighs sixty 



Ben Davis Apples, Perrine's Ranch. 



it must be supplied by artificial means through irriga- 

 tion, else the farmer may as well retire from business, 

 unless he admires a useless expenditure of labor year 

 after year. 



It is alleged by men of the highest scientific stand- 

 ing, men who have made irrigation agriculture a pro- 

 found study, and have performed a multitude of practi- 

 cal experiments to demonstrate the verity of their propo- 

 sition that about forty inches of water whether rainfall, 

 or evenly distributed artificially, is the proper and 

 essential quantity to successfully grow a crop from the 

 planting to the harvest. Some claim that a lesser 

 quantity will be sufficient. Thus, Professor King found 

 that he could use 34 inches for the growing season in 

 Wisconsin. In California from 7% to 20 inches will 

 answer the purpose; in Colorado. 22 inches; in India 

 48 inches are necessary, and 50 inches in Prance and 

 Italy. All these calculatioas are based upon the 



pounds avoirdupois. At the rate of three hundred 

 bushels per acre, which is a very large yield to the 

 acre, the weight will reach 18,000 pounds, or nine tons. 



In the case of sugar beets, the production runs all 

 the way from fifteen to thirty-five tons per acre. 



Now, it has been calculated that potatoes and beets 

 contain from 80 to 90 per cent of their weight in 

 water, or its equivalent, and at 90 per cent, to give 

 them the benefit of the largest possible quantity of 

 fluidity, an acre of potatoes would contain about 8y 2 

 tons of water, and an acre of beets about 32 tons. 



It is impossible to believe that this small quantity 

 of vegetable extract required the distillation in the 

 plant of 4,526 tons of water in ninety days, and the fact 

 is that it does not. In a former chapter it is said that 

 moisture, or water in the shape of moisture, is taken 

 into the plant by way of the roots, and after being 

 utilized in the economy of the plant, it is discharged 



