THE IRRIGATION AGE. 



41 



can ways of farming. Strong teams, heavy plows, and 

 large scrapers were substituted for the hoe, spade, and 

 mattock of the Mexicans. The owners of these farms 

 and outfits had also large ideas of how land should 

 be prepared for irrigation. In their opinion the small 

 check bed, twenty by forty feet, surrounded by a ten- 

 inch bank, might do very well to water Mexican chili, 



Contour lines. 



but alfalfa fields, farmed on a big scale, required to be 

 prepared in a wholly different manner. These men, ac- 

 cordingly, went from one extreme to the other. From 

 checks containing the one-twentieth of an acre they in- 

 creased the size to ten, twenty, and thirty acres in each 

 check. These large checks have proved failures from 

 the start. The farmers who adopted this style years 

 ago have had no end of trouble in lowering the levees 

 and reducing the size of the checks. 



The checks of from two to five acres, which the 



Contour checks. 



farmers around Bakersfield considered about the proper 

 size twenty years ago, are now thought to be too large, 

 there are, of course, conditions in which large checks 

 may be used to good purpose. When, for example, the 

 slope of the land is slight and the volume of water 

 which may be turned into the supply ditch is large, 

 there might be a small saving in having eight checks 

 instead of sixty in a forty-acre tract. However, this 



Rectangular Checks. 



slight saving in the first cost of preparing the land 

 is soon lost in the waste of water, unequal distribution, 

 and consequent lessened yields. 



Mr. Steve Luin, superintendent of the Madera 

 Canal and Irrigation Company, advocates in the strong- 



est manner a reduction of the present checks, which 

 vary from three to five acres, to about one and one- 

 half acres on all the 10,500 acres irrigated by that 

 canal. At present the usual custom throughout the 

 San Joaquin Valley is to limit the cheeks to an average 

 of about three-fourths of an inch. 



As regards arid America, the check system of irri- 

 gation is confined principally at the present time to the 

 San Joaquin Valley. It is also used in irrigating the 

 rice fields of Louisiana and Texas,* and a modification 

 of the same system is to be found on the alfalfa fields 



T 



Check box, showing section across embankment at top and 

 lengthwise of bank at bottom. 



of Arizona and in the Imperial Valley in southeastern 

 California, 



There are several reasons why irrigation by checks 

 should be so popular in the San Joaquin Valley. The 

 soil in many parts is porous, containing a high per- 

 centage of fine sand. In such districts it is doubtful 

 if any other method of applying water would be so 

 successful. As a rule, the slope is also slight, which 

 enables the farmer to form check after check with only 

 a few inches of difference in elevation. . It is due, how- 

 ever, to the character of the streams which furnish 

 the water supply for the valley that the check system is 

 so generally used. These streams head in the Sierra 

 Nevada Mountains, where the precipitation, particular- 

 ly in the form of snow, is heavy and they are all sub- 

 ject to floods in the spring. After these spring floods 

 subside, the flow is often extremely low, owing to the 

 small catchment area, the lack of summer rains, and 

 the excessive evaporation. Irrigation works have ac- 

 cordingly to be planned to take care of a large volume 

 of water during the spring months. The Tuolumne 

 Eiver, to cite a somewhat extreme case, frequently dis- 

 charges enough water to cover 20,000 acres a foot deep 

 in a single day in May, while the total discharge for the 

 month of August may be little more than this. In 

 great fluctuations of this nature not only must the 

 canal engineer and superintendent adapt their struct- 

 ures to carry large volumes, but the irrigator is under 

 the same necessity to form his checks, sluice boxes, and 



*U. S. Dept. Agr., Office of Experiment Stations Bui. 113, Irrigation 

 of Rice in the United States. 



