206 



Irrigation and Drainage 



Table showing the loss of water from, a virgin clay loam through mulches 1, 3, 

 and 3 inches deep, when cultivated once in two weeks, once per week, and 

 twice per week 



Not Once in Once per Twice per 



cultivated 2 weeks week week 



Cultivated 1 inch deep PER ACRE PE ACRE PER ACRE PER ACRE 



The loss in tons per 100 days was 724.1 551.2 545 527.8 



The loss in inches per 100 days was. . 6.394 4.867 4.812 4.662 



The percentage of water saved was. . 23.88 24.73 27.1 



Cultivated 2 inches deep 



The loss in tons per 100 days was.... 724.1 609.2 552.1 515.4 



The loss in inches per 100 days was.. 6.394 5.38 4.875 4.552 



The percentage of water saved was.. 15.88 23.76 28.81 



Cultivated 3 inches deep 



The loss in tons per 100 days was.... 724.1 612 531.5 495 



The loss in inches per 100 days was.. 6.394 5.28 4.694 4.371 



The percentage of water saved was. . 15.49 26.6 31.64 



It will be seen from this table that with each of the three 

 depths of cultivation the loss of water decreased with the fre- 

 quency, so that the per cent of moisture saved by the cultivation, 

 when computed on that which was lost with no cultivation, was 

 more than 31 for 3 inches deep twice per week, as against a sav- 

 ing of only 15 per cent where the same cultivation was made only 

 once in two weeKs. That is to say, if one is cultivating ground 

 of this character 3 inches deep twice per week, the saving over 

 no cultivation may be at the rate of 2.29 tons per acre per day, 

 or 22.9 tons per each 10 days, or 2 acre -inches per 100 days. 



The results presented in the table were obtained in our 

 plant -house, with cylinders 52 inches deep and 18 inches in 

 diameter, filled with soil under a nearly still air and a compara- 

 tively low mean temperature, not exceeding 55 F., during the 

 short days and long nights of December and January, so that 

 the observed losses in the several cases must be looked upon as 

 small, and below what may obtain under field conditions. It is 

 plain, therefore, that in orchard irrigation and in arid climates, 

 under a clear sky, dry air and high temperature, the duty of 

 water during the long seasons may be very materially increased 

 by adequate cultivation, and decreased by the lack of it. 



The same will also be true, but in a less marked degree, 



