IQII 



objection to this method is that the 

 checks are too small for orchard tracts 

 in furrow irrigation. 



The best orchardists believe that fre- 

 quent examinations of stems, branches, 

 foliage and fruit are not enough. The 

 roots and soil should likewise be exam- 

 ined. The advice of such men to the 

 inexperienced is: Find out where the 

 bulk of the feeding roots is located, 

 ascertain the nature of the soil around 

 them and make frequent tests as to the 

 moisture which it contains. In a citrus 

 orchard of sandy loam samples are taken 

 at depths of about three feet, and the 

 moisture content determined by exposing 

 the samples to a bright sun for the 

 greater part of a day. It is considered 

 that six per cent by weight of free water 

 is sufficient to keep the trees in a vig- 

 orous condition. 



Doctor Loughridge, of the University 

 of California, in his experiments at Riv- 

 erside, California, in June, 1905, found 

 an average of 3.5 per cent in the upper 

 two feet and an average 6.16 per cent 

 below this level in an orchard which had 

 not been irrigated since October of the 

 preceding year. It had received, how- 

 ever, a winter rainfall of about sixteen 

 inches. On examination it was found 

 that the bulk of the roots lay between 

 the first and fourth foot. In June these 

 trees seemed to be merely holding their 

 own. When irrigated on July 7 they 

 began to make new growth. A few days 

 after the water was applied the per- 

 centage of free water in the upper four 

 feet of soil rose to 9.64 per cent. The 

 results of these tests seem to indicate 

 that the percentage by weight of free 

 moisture should range between five and 

 ten per cent in orchard loams. 



Many fruit growers do not turn on the 

 irrigation stream until the trees begin to 

 show visible signs of suffering, as a 

 slight change in color or a slight curl- 

 ing of the leaves. In thus waiting for 

 these signals of distress both trees and 

 fruit are liable to be injured. On the 

 other hand, the man who ignores these 



BETTER FRUIT 



■BoxA X- 



I 



Oi'er/'/otv 

 Stone/ 



Oi/er/'/oyi/ 

 Stone/. 



'Tumexjt S t anc/ 



Private Latere// 



~7W 



m m 



m(3 m 



Figure 14- 



-EARTHEN HEAD DITCH LINED 

 WITH CONCRETE 



u;vRE 15— USE OF PIPES IN FURROW IRRIGATION 



symptoms and pours on a large quantity 

 of water whenever he can spare it, or 

 when his turn comes, is apt to cause 

 greater damage by an overdose of water. 



For nearly half the entire year the 

 fruit trees of Wyoming and Montana 

 have little active, visible growth, whereas 

 in the citrus districts of California and 

 Arizona the growth is continuous. A 

 tree when dormant gives off moisture, 

 but the amount evaporated from both 

 soil and tree in winter is relatively small, 

 owing to the low temperature, the lack 

 of foliage and feeble growth. A heavy 

 rain which saturates the soil below the 

 usual covering of soil mulch may take 

 the place of one artificial watering, but 

 the light shower frequently does more 

 harm than good. The number of irri- 

 gations likewise depends on the capacity 

 of the soil to hold water. If it readily 

 parts with moisture light but frequent 

 applications will produce the best results, 

 but if it holds water well a heavy appli- 

 cation at longer intervals is best, espe- 

 cially when loss by evaporation from the 

 soil is prevented by the use of a deep 

 soil mulch. 



In the Yakima and Wenatchee fruit 

 growing districts of Washington the first 

 irrigation is usually given in April or 

 early in May. Then follow three to four 

 waterings at intervals of twenty to thirty 

 days. At Montrose, Colorado, water is 

 used three to five times in a season. At 

 Payette, Idaho, the same number of irri- 

 gations is applied, beginning about June 

 1 in ordinary seasons, and repeating the 

 operation at the end of thirty-day inter- 

 vals. As a rule the orchards at Lewis- 

 ton, Idaho, are watered three times, 

 beginning about June 15. From two to 

 four waterings suffice for fruit trees in 

 the vicinity of Boulder, Colorado. The 

 last irrigation is given on or before Sep- 

 tember 5, so that the new wood may 

 have a chance to mature before heavy 

 freezes occur. In the Bitter Root Val- 

 ley, Montana, young trees are irrigated 

 earlier and oftener than mature trees. 

 Trees in bearing are, as a rule, irrigated 

 about July 15, August 10 and August 20 

 of each year. In San Diego County, 

 California, citrus trees are watered six 

 to eight times and deciduous trees three 

 to four times in a season. 



The duty of water for one acre as 

 fixed by water contracts varies all the 

 way from one-fortieth to one four-hun- 

 dredth of a cubic foot per second. In 

 general the most water is applied in dis- 

 tricts that require the least. Wherever 

 water is cheap and abundant the tend- 

 ency seems to be to use large quantities, 

 regardless of the requirements of the 

 fruit trees. In Wyoming the duty of 



Page 25 



water is seldom less than at the rate of a 

 cubic foot per second for seventy acres. 

 In parts of Southern California the same 

 quantity of water not infrequently serves 

 400 acres, yet the amount required by the 

 fruit trees of the latter locality is far in 

 excess of that of the former. 



In recent years the tendency all over 

 the West is toward a more economical 

 use of water, and even in localities where 

 water for irrigation is still reasonably 

 low in price it is rare that more than 

 two and one-half acre feet per acre is 

 applied in a season. This is the duty 

 provided for in the contracts of the Bitter 

 Root Valley Irrigation Company of 

 Montana, which has 40,000 acres of fruit 

 lands under ditch. Since, however, the 

 water user is not entitled to receive more 

 than one-half of an acre foot per acre 

 in any one calendar month it is only 

 when the growing season is long and. 

 dry that he requires the full amount. 



In the vicinity of Boulder, Colorado, 

 the continuous flow of a cubic foot per 

 second for 105 days serves about 112 

 acres of all kinds of crops. This amount 

 of water, if none were lost, would cover 

 each acre to a depth of 1.9 feet. In other 

 words, the duty of water is a trifle less 

 than two acre feet per acre. 



In 1908 the depth of water used on a 

 twenty-one and a half acre apple orchard 

 at Wenatchee, Washington, was meas- 



FiGURE 16— SECTION OF STANDPIPE 

 OUTLINED IN FIGURE 15 



ured and found to be twenty-three inches 

 The trees were seven years old, and pro- 

 duced heavily. This orchard was watered 

 five times, the first on May 13 and the 

 last on September 23. In San Diego 

 County, California, one miner's inch 

 (one-fiftieth of a cubic foot per second) 

 irrigates from six to seven acres near 

 the coast, where the air is cool and 

 evaporation low, but twenty miles or so 

 inland the same amount of water is 

 needed for about four acres. 



On the sandy loam orchards of Orange 

 County, California, it has been demon- 

 strated that two acre inches every sixty 

 days is insufficient to keep bearing trees 

 in good condition. The rainfall of this 

 locality averages somewhat less than 

 twelve inches per annum, but about 



4 



