THE IKRIGATION AGE. 



703 



about one-eighth of a mile long Doctor Loughridge found 

 in his experiments at Riverside, Cal., that in some parts 

 of the orchard the soil was wet as a result of a recent 

 irrigation to depths of 20 to 26 feet, while in other parts 

 the moisture had not penetrated beyond the third foot. 



One of the best ways of finding out whether much 

 water is -lost by deep percolation is to dig cross trenches 

 as deep as the feeding roots go. The moisture which 

 passes the deepest roots in its downward course may be 

 considered wasted. 



An example of fairly even and desirable moisture dis- 

 tribution from furrows is shown in Sections XI and XII 

 of figure 28, where the three curved lines show the mar- 

 gins of the wetted soil at the end of one, two, and three 

 clays, respectively. 



Removal of Waste Water. 



The loss of water is not the only effect of deep per- 

 colation. The water which escapes in this and other ways 

 usually moves through the soil at a rather slow rate of 

 speed until it reaches some underground body of water 

 at a lower level. In case orchards have been planted at 

 lower levels when the subsoil 

 was dry, care should be exer- 

 cised in observing the rise of 

 the ground water level. The 

 small post-hole auger shown in 

 figure 29 is one of the most 

 convenient tools to use in mak- 

 ing test wells to keep track of 

 the behavior of the ground 

 water. Before the deepest roots 

 of the fruit trees are submerged, 

 artificial drainage ought to be 

 provided. Otherwise the ground 

 water will at first lessen the 

 yield and finally destroy the 

 trees. 



The drainage of orchard 

 tracts usually progresses in 

 more or less distinct and sep- 

 arate stages. When the ground 

 water begins to be a menace, 

 the natural ravines in the vicin- 

 ity are cleared of weeds and 

 other rubbish and deepened. If 

 the ground water continues to 

 Fig. 29. Soil Auger Used to rise, the open drains are deep- 

 Locate Ground Water Level. ened an( j extende d or else the 

 excess water i s withdrawn 

 through covered drains. Open drains in orchards occupy 



\aluable land, obstruct field work, and are expensive to 

 maintain. Some of these objections can be lessened if 

 not removed by locating such drains along the lower 

 boundary of the tract. When this plan is followed, cov- 

 ered drains are frequently laid among the trees and dis- 

 charge into the open drains. Sometimes the source and 



Fig. S7. Tank Experiments at Reno, Nev., to Determine Effects of 

 Soil Mulches in Checking Evaporation. 



direction of the waste water which is waterlogging an 

 orchard can be traced beneath the surface. In this event 

 it is well to try to intercept its passage before it reaches 

 the trees. This can be done by an open drain, but a cov- 

 ered pipe drain of the required size is preferable. Where 

 durable lumber is cheap, box drain - similar to that 

 the rate of interest low, but sooner or later the trees will 



3 * 5 6 78 9 10 II /2 t3 M /S 16 17 /8 



eo 21 ze 23 



zs 26 27 ee 29 30 31 32 33 34 35 36 37 36 39 



Ft. 

 "1 



f/ 4Z f3 tf tS #6 V7 #B f9 SO SI 52 S3 SU SS 56 S7 SO Sff 60, V 62 63 64 6S 66 67 68 69 70 71 7i 73 Tf- 7S 76 T7 78 79 39 



FIG. 2. Outlines of percolation under sixteen furrows in orchard 53 under the Gage Canal Company, Riverside, Cal. 



