106 



THE IRRIGATION AGE. 



MAKING FURROWS. 



The "furrows for crops like potatoes, which are 

 planted in straight rows, are made with an ordinary 

 walking plow with a cultivator having a large shovel 

 attached, or with a lister. 



Sometimes it is very desirable to irrigate grain, 

 clover or alfalfa from furrows, on account of the lia- 

 bility of the soil to bake when flooded. In making 

 furrows for such crops home-made implements are 

 most commonly employed. These usually make small 

 furrows from two to four inches in depth and from 

 1.5 to four feet apart down the steepest slope from the 

 head ditch. The home-made furrower shown in Fig. 

 18 is well suited for this purpose. 



When the soil will not be injured by rolling, pro- 

 jections in the form of an inverted V are sometimes 

 fastened around the circumference of the roller and 

 each of these makes a well-defined and smooth fur- 

 row. 



Some years ago small, shallow furrows made by 

 cultivator teeth were about the only kind to be seen 

 in orchards. Now a small number of large, deep 

 furrows are frequently used instead. Plate III, Pig. 



o 



B jard Flumes for Use in Furrow Irrigation. 



2, shows an implement for making such furrows in 

 use on J. H. Williams' large orange orchard near Por- 

 terville, Cal. He took a cultivator and removed all 

 the shovels. Two double-mold shovels were attached 

 to an arm, which is fastened by the clamps of the 

 cultivator. The right-hand plow extends out to the 

 side, so that the distance between the centers of the 

 two plows is 4.5 feet. This enables the driver to make 

 a furrow beneath the outer branches of one row of 

 trees in going one way and of the adjacent row in re- 

 turning. With trees twenty feet apart, four furrows 

 are made, and these can be arranged in the best way 

 by adjusting the arms of the plows. The lever arm 

 of the cultivator controls the depth and size of the 

 furrows. 



. Shallow Versus Deep Furrows. Ten or fifteen 

 years ago the prevailing custom among fruit-growers 

 was to make a considerable number of shallow furrows 

 between the rows of trees. While this practice is still 

 followed by many, the general trend of the best prac- 

 tice is toward a smaller number of deeper furrows. A 

 desire to economize water by lessening the amount 



evaporated was doubtless the principal reason for a 

 change of usage. Besides, running water in deep fur- 

 rows tends to break up hard subsoil and to promote 

 deep rooting. 



Owing to the scarcity and value of water in 

 southern California, the orchardists have been forced to 

 make a close study of the effects produced by different 

 methods. This office began a series of experiments in 

 June, 1903, at Pomona, Cal., to determine the actual 

 difference in loss of water by evaporation between the 

 shallow and deep furrows. The experiment has not 



Fig. 15 V-shaped Flumes Use in Furrow Irrigation. 



been continued sufficiently long to warrant any con- 

 clusive statements. The results, however, show a 

 marked gain in favor of deep furrows. From June 

 20 to October 24, 1903, the average amounts evaporated 

 from equal areas of the same kind of irrigated soil for 

 the different modes of applying water were as follows : 



Acre feet. 



Irrigation by flooding 0.62 



Irrigation by furrows 3 inches deep 55 



Irrigation by furrows 12 inches deep 41 



Length, Grade and Number of Furrows. One of 

 the common mistakes in furrow irrigation is to try to 

 run water from end to end of a long field. A uniform 

 distribution can not be made from long furrows. Their 

 length should rarely exceed 660 feet (forty rods), 

 which measures the side of a 10-acre tract. A tract 

 from forty to eighty rods long in the direction of the 

 furrows should have two head ditches and longer fields 

 a. larger number. 



The fall or grade of furrows may vary between 

 about 4.4 feet per mile and eighty-eight feet per mile, 



* I 



Fig. 16 Cross Section 8-inch Cement Flume. 



or from one to twenty inches in 100 feet. On ordinary 

 soils a fall of from three to four inches to 100 feet is 

 to be preferred. When the slope of a field is too great 

 that of the furrows may be reduced by changing their 

 direction. 



The number of furrows in orchards depends on 

 the age of the tree, the space between the rows and the 

 depth of the furrows. Nursery stock is irrigated by 

 one or two furrows and young trees by from two to 

 four. Only one very deep furrow made by a subsoiler 

 may be run between the rows, while four is a common 

 number for those of medium size. Shallow furrow* 



