THE IRRIGATION AGE. 



311 



damp, which forms a stronger and more impervious 

 dam. For this reason a larger head of water can be 

 used for the second irrigation. This irrigation follows 

 the first in from twelve to twenty-five days. Each 

 irrigator is given 200 inches of water, and this stream 

 is kept running night and day as in the first irrigation." 



IRRIGATION PRACTICE IN NEVADA. 



The conditions under which the various crops are 

 grown in the scattered valleys of Nevada differ widely. 

 The observations of the writer during his one yearns 

 residence in the State have been confined mainly to the 

 practices in the Truckee Valley. In this valley there 

 is and always has been an abundant supply of irriga- 

 gation water, which must account in part for the meth- 

 ods used. To one who is familiar with the economy 

 practiced by ranchers in other regions where this abund- 

 ance does not exist the practice in this valley seems 

 wasteful. Reports from other parts of the State, where 

 at times a scarcity of water exists, seem to indicate 

 that there, as in the Truckee Valley, the number of 

 irrigations uesd in growing a crop is limited only by 

 the amount of water to be had. 



B 



Fig. 29. Flooding from Field Laterals. 



NATIVE GRASSES. 



In the growing of native grasses not only are the 

 most primitive methods of irrigation used, but appa- 

 rently the greatest excess of water. Mr. J. D. Stan- 

 nard, in his report of irrigation investigations in the 

 Humboldt River Valley (Nevada Station Bulletin 54), 

 speaks of the growing of native hay in the bottom 

 lands along the Humboldt as follows: 



"For a number of years after these lands were 

 occupied the natural channels of the stream were not 

 of sufficient capacity to accommodate the volume of 

 water that came down during the floods of spring 

 and early summer. The streams at these times would 

 overflow the meadow lands for a sufficient length of 

 time to produce a crop. As more and more water was 

 taken out by irrigators higher on the stream, the vol- 

 ume of water during the flood seasons became inade- 

 quate to irrigate those meadow lands as was formerly 

 done, and dams were placed in the channels to force 

 the water out of the streams and over the meadows as 

 in former times." 



This is called irrigation by natural flow. Wherever 



native grass is grown it is customary to flood it, and 

 in some cases water is allowed to run over the land 

 throughout the entire growing season. 

 ALFALFA. 



Alfalfa is grown in Nevada with from one to twen- 

 ty-two irrigations in a season. Mr. Stannard states 

 that in the Humboldt River Valley the crop is irrigated 

 from one to eight times; that the lands receiving one, 

 two, and three irrigations have given practically the 

 same yields of hay, or yields greater than those obtained 

 from other lands irrigated six, seven and eight times; 

 and that the highest yields were from lands irrigated 

 four or five times. 



In the Truckee Valley the common practice is to 

 give alfalfa ten or twelve irrigations, though some men 

 irrigate less and others as many as twenty-two times. 

 The character of the soil will in many cases account for 

 differences in the number of irrigations required by a 

 crop. Much of the valley soil is so gravelly and por- 

 ous that it does not hold water well and therefore re- 

 quires more frequent irrigation than a closer, more 

 compact soil. 



The character of the land upon the station farm 

 is such as to indicate that it would require the maxi- 



Fig. 30 Flooding Irom ditches running down steepest slope. 



mum amount of water to grow a crop, and here good 

 results were had from seven irrigations. In fact, an 

 originally poor stand of alfalfa has been much im- 

 proved by using less water than was used by the former 

 owner of the land. 



Mr. Stannard's report suggests what the station 

 experience indicates, that an excessive use of water is 

 not only unnecessary, but is detrimental to the crop. 

 Alfalfa is a plant that thrives best in warm soil and 

 atmosphere. The water of mountain streams is always 

 cold. The too early and too frequent applications of 

 water keep the soil cold, and thus retard the growth 

 of the plant. These conditions that check the growth 

 of alfalfa stimulate the growth of the less desirable 

 shallow-rooted grasses, which are then said to "run out" 

 the alfalfa. 



Two methods of irrigation are used in the culti- 

 vation of alfalfa the so-called flooding method, where 

 the land is flooded by means of parallel ditches extend- 

 ing across the field forty or sixty feet apart, and the 

 more extensively used furrow method. 



The furrow method is used alike for alfalfa, grain, 

 and garden. It finds faror because it makes possible 

 the irrigation of land that could not be flooded on 



