THE IERIGATION AGE. 



247 



The water, after it leaves the lateral, is directed into 

 the small channels made by the marker and flows rap- 

 idly over the surface. However, the water is not en- 

 tirely confined to the furrows, but is allowed to over- 

 flow. They simply serve as guides to carry the water 

 to all parts of the field, thus insuring a thorough wet- 

 ting of the surface. Where the small furrows are made 

 across the slope they aid in distributing the water trans- 

 versely, and a larger stream may be taken from the 

 main lateral. Where the marks run with the slope, 

 more attention is required of the irrigator to prevent 

 them washing into large channels and becoming col- 

 lectors rather than distributers of the water. In some 

 instances the marker is handled so as to place the chan- 

 nels on a slight grade. This method gives perhaps the 

 best results. During the first irrigation close atten- 

 tion must be given to the distribution, and dirt must 

 be put here and there in the small channels to make 

 sure thai the water spreads evenly. Each time the 

 field is irrigated the small channels become more fixed, 

 and toward the end of the season hut little attention 

 is required to thoroughly irrigate the tract. 



The main distributary laterals in the field should 

 be placed from five to eight rods apart, depending upon 

 the slope of the land and the nature of the soil, and 

 may be given grades of from one-half inch to an inch 

 per rod. Each lateral should carry from two to three 

 cubic feet of water per second, as one man can usually 

 handle this volume with ease after getting his stream 

 set. 



Alfalfa is irrigated in much the same manner as 

 that just described. It is usually sown with a nurse 

 crop, either wheat or oats, which protects the young 

 alfalfa and is ready for harvest before the alfalfa gets 

 to such height as to interfere with its growth. 



Such crops as potatoes, sugar beets, and other veg- 

 etables which are grown in rows are irrigated by the 

 furrow method. These furrows are made with ordinary 

 walking plows after the crop has come up, and the 

 water reaches the roots from the furrows. During the 

 early period of growth water is turned into each fur- 

 row. When the crop is approaching maturity, or when 

 the water supply becomes short, water is turned into 

 alternate furrows only. 



METHODS IN USE IN COLORADO AND WYOMING. 



A mistake often made by the inexperienced irri- 

 gator when laying out his field laterals is in placing 

 them too far apart. In old-established colonies, like 

 Grceley and vicinity, in irrigating alfalfa, oats, wheat, 

 and other grains by the flooding system the distance 

 between laterals varies from twenty-five to thirty steps 

 seventy-five to ninety feet. In the grain and alfalfa 

 fields with varying slopes, in the vicinity of Greeley, 

 the field laterals were rarely found to be under seventy- 

 five feet to over 100 feet apart. Old irrigators have 

 learned from experience how unwise it is to attempt 

 to force a sheet of water over am intervening space of 

 200 or 300 feet, especially where the head of water is 

 small and the slope of the ground moderate. The es- 

 sential thing in applying water to crops by the flooding 

 system is to advance the sheet of water uniformly over 

 the area irrigated so that all parts of that section of the 

 field to which water is being applied may receive, as 

 nearly as possible, the same amount of water. Near 

 Greeley one of the most economically managed farms, 

 as far as water is concerned, comprising 160 acres, 



is entitled to a head of water consisting of two ditch 

 rights and two reservoir rights. A ditch right, as men- 

 tioned here, entitles the possessor to fifty-two Colorado 

 miner's inches for a period extending from May 1 to 

 August 1. A reservoir right entitles the owner to thirty- 

 two Colorado miner's inches for a period of ten days. 

 Converting these figures into cubic feet per second, from 

 May 1 to August 1 the farm receives 2,708 cubic feet 

 per second from the two ditch rights and for ten days 

 after August 1 not necessarily consecutive the farm 

 receives 1.67 cubic feet per second from the two reser- 

 voir rights. 



The main lateral on this farm has a top width of 

 three feet, a bottom width of two feet, and side slopes of 

 one to one. The field laterals are placed from seventy- 

 five to ninety feet apart in the grain and alfalfa fields. 

 Canvas dams are placed in the laterals so as to back up 

 the water for a distance of seventy-five feet, when it is 

 allowed to flow either over the lower bank or through 

 cuts made in the bank at intervals of ten or fifteen feet. 

 The owner of this farm, with a head of one and one-half 

 ditch rights, 2.03 cubic feet per second, can spread water 

 over the surface of his fields between laterals placed at 

 thirty steps apart with ease and effectiveness. 



The furrow system of irrigation is practiced on this 

 farm for root crops, such as sugar beets and potatoes, 

 which are planted in long rows, the beets about three 

 feet apart and the potatoes about five feet. The soil is 

 a sandy loam and the slopes are such that the irrigator 

 can flow water down the furrows for a distance of 800 

 feet from the main lateral. The distance which a stream 

 of water can be successfully run in furrows depends 

 upon the texture of the soil through which they extend. 

 Where the soil is coarse and absorbs water quickly the 

 distance for the same head of water must be shorter 

 than where the texture of the soil is finer and absorbs 

 water more slowly. The stream in the furrows must 

 be made to flow with a velocity sufficient to carry it 

 to the lowest extremity of the field or the next lateral 

 below, but at the same time must not flow with such 

 swiftness as to cause scouring of the banks of the fur- 

 row or cutting deep into the furrow. The implement 

 most generally used for ditching potatoes and sugar 

 beets is the wood-beam wing-shovel plow. 



One of the best examples of high-class irrigation 

 which has been observed is the watering of a field of 

 potatoes on a hillside. It cost the owner and irrigator of 

 this piece of ground three years of hard labor and bitter 

 experience to learn to run his furrows between rows in 

 such a way as to prevent scouring. At first he attempted 

 to run his furrows diagonally across the hillside, but 

 the grade wa-s too steep and the water scoured the fur- 

 rows, while his crop of potatoes was a failure owing to 

 the lack of water at the head of his rows and the over- 

 abundance at the lower ends. The next year he ran his 

 furrows around the hill, but they did not conform to 

 the contour of the ground sufficiently to altogether pre- 

 vent scouring, and his crop was poor. Finally, he has 

 fitted the curve of his furrows to the contour of the hill 

 in such a way as to prevent all scouring, and now his 

 crop of potatoes from this hillside is as good as any crop 

 he raises on comparatively level ground. 



CAKE OF LATERALS. 



Laterals, like machinery, need more or less constant 

 attention when in use. If they are neglected, breaks, 

 leaks, and blocking of the channel may occur, and prob- 



