1906 



FORESTRY AND IRRIGATION 



417 



the hands" of the Forest Service in 

 the work which it has to do. Persons 

 residing near the forest reserves are 

 enthusiastic over the benefits already 

 accruing, even after so few years of 

 Government administration, and pe- 

 titions are coming in from all quarters 

 for the creation of new reserves. Lum- 

 bermen are quickly adopting forest 

 ideas and are cutting for future crops. 

 Lumber manufacturers are utilizing 



their woods to the greatest possible 

 advantage in many instances and waste 

 is being eliminated in a country which 

 is wasteful by nature. 



In short, it is coming to be true that 

 the two chief reasons for calling at- 

 tention to the popular conceptions con- 

 cerning forestry, is to note how quickly 

 they are passing, and to help a little 

 toward hastening that passage even 

 more. 



THE DUTY OF WATER 



BY 

 ALEX McPHERSON 



In charge of the Experimental Farm of the Twin Falls (Idaho) Land and Water Co. 



"T" HE soil on the Twin Falls tract 

 is commonly considered to be of 

 volcanic origin, varying from two 

 feet to an unknown depth, consist- 

 ing of very fine particles. 



When we began work on the 

 Twin Falls experimental farm in 

 1905, we dug prospect holes from 

 'seven to 10 feet in depth in order to 

 determine the character of the soil, 

 and the amount of moisture present. 

 The only difference we observed in 

 the soil was that the first foot was 

 somewhat darker in color. With re- 

 fard to moisture, the first 18 inches 

 contained some moisture, but be- 

 low it was perfectly dry, conse- 

 quently we irrigated before planting. 

 It required 24 to 36 hours to satu- 

 rate to a depth varying from seven 

 to 10 feet. 



No effort was made to determine 

 the quantity of water used during 

 the season after that. This year 

 (1906) it was determined to meas- 

 ure the amount of water used on the 

 farm, and the amount running off 

 as waste, as well as the evapora- 

 tion, with a view to determining the 

 quantity of water necessary to keep 

 the soil in proper condition. 



The miners' inch was used in 

 measuring half a cubic foot per sec- 

 ond of the farm, and a device was 

 employed in connection to obviate 

 any fluctuation in the head. A weir 



with an automatic register attached 

 was used as a check on the miners' 

 inch measurement in order that we 

 might be sure that just the amount 

 of water desired was supplied. 



At the lower end of the farm, a 

 weir register was installed for meas- 

 uring the waste. Elias Nelson of the 

 Bureau of Irrigation and drainage 

 investigation, added an evaporating 

 tank. 



We began irrigating May 2, with 

 the amount of water allowed under 

 the contract between the settlers 

 and the Twin Falls Land & Water 

 company that is 1-80 of a cubic 

 foot per second per acre, continuous 

 flow. 



The amount of water applied dur- 

 ing each month up to the first of 

 September, 1906, is given below, as 

 well as the waste and evaporation : 



Total amount applied, 36.10 

 inches ; total percentage, 100 plus. 



Total amount precipitation, o; 

 total percentage, 12.4. 



Total amount wasted, 4.49; total 

 percentage, 7.4. 



Total amount evaporated, 28.06 

 total percentage, JJ.J. 



Total per cent wasted, 7.4. 



Total per cent evaporated, yj.y. 



Total difference (or water retain- 

 ed by the soil), 5.694 inches; 15.8 

 per cent. 



