IRRIGATION 



IRRIGATION 



1687 



the plan. On the muck lands of the North, the object 

 is accomplished by closing the drainage outlets and so 

 raising the water-table that the surface soil is moist- 

 ened. It is not good practice to keep the water-table 

 high, because it inhibits the proper root-development 

 of the plants. 



Growers of vegetables in the eastern half of the 

 United States are using various types of overhead 

 irrigation far more than other methods. These sys- 

 tems usually. involve the establishment of lines of pipe 

 mounted on posts and carrying either sprinklers or 

 small nozzles. These lines are so spaced that the 

 ground may be evenly covered by the spray. Some 

 types of sprinklers are so constructed as to revolve 

 and cover an area of perhaps 25 feet radius. These are 

 objectionable because they cannot cover the ground 

 as evenly as other types. 



More commonly employed are small nozzles which 

 consist merely of a threaded plug of brass through 

 which a straight hole is accurately drilled. These are 

 set in holes in the pipe-line. Recently various modifica- 

 tions and improvements in these nozzles have been 

 made. The nozzle line is screwed together and mounted 

 on the posts, and a special machine equipped with a 

 small level is used for tapping and threading the holes. 

 The nozzle line is mounted with a union in which is 

 set a handle for turning to cast water far to each side or 

 to cover the near gound by throwing vertically. The 

 nozzles are usually spaced about 3 feet apart and throw 

 a fine solid stream which breaks at some distance from 

 the opening. When the water reaches the ground, it is 

 a fine mist similar to a light rain. Twenty-five to forty 

 pounds of pressure is sufficient to cover a belt ranging 

 from 20 to 30 feet on either side of the line. 



A long line, of say 300 feet, would consist of 100 feet 

 of l}4- m ch pipe, 100 feet of 1-inch pipe, and 100 feet 

 of %-inch pipe. 



Nozzle lines are supported in many different ways. 

 The consensus of opinion at present is that they should 

 be about 7 feet above the ground to avoid interference 

 with work that is being done. These posts must be set 

 15 feet apart to carry %-inch pipe and a little farther 

 apart for larger sizes. Posts of pipe or wood are most 

 commonly used, but suspension from a cable supported 

 by posts 100 feet or so apart is gaining in favor with 

 vegetable-gardeners. 



Occasionally, for temporary purposes, as for a single 

 watering of young strawberry plants, the pipes are 

 simply laid on the ground and turned by the handles 

 in the usual way. Other growers have small horses 

 which may be placed on the ground to carry the line 

 temporarily. Mechanism has been devised by which a 

 large number of lines may be automatically controlled 

 from a single point, turning the spray constantly from 

 one side to the other. 



The main at the end of a field may be buried and the 

 lines supplied through risers, or it may be carried on the 

 first post of each of the rows which support the nozzle 

 lines. 



Comparatively few gardens are so located that a 

 suitable supply of water is not available at reasonable 

 cost. There are several possible sources. Some gar- 

 deners pump directly from streams or ponds, ordinarily 

 using a gasolene engine and the triplex type of pump. 

 In other sections, where the water-table is relatively 

 near the surface, and where the ground-water is abun- 

 dant, wells are sunk. Some employ a number of driven 

 wells and gather water simultaneously from all of them. 

 At Rochester, New York, many wells of large diameter 

 with concrete walls are to be found. The method 

 of sinking them is ingenious. A circular ditch of the 

 desired diameter, say 15 to 25 feet, and about 2 feet 

 wide and 4 feet deep is dug. In this is built by means of 

 wooden forms a concrete ring. The lower edge of this 

 ring is beveled outward at an angle of perhaps 30. 

 The ring is strongly reinforced and short bits of pipe 



are inserted radially. After the concrete in this ring 

 has set and the forms have been removed, the work of 

 digging is begun within. The earth is removed, one 

 man seeing that it is taken evenly from the sides of the 

 well under the sharpened edge. As the work progresses 

 the ring sinks into the ground and radial concrete 

 blocks are built upon it to serve as a wall. The well 

 may be sunk to a depth of 20 or even 25 feet. The large 

 diameter offers great gathering surface, and an abun- 

 dance of water may be secured from a stratum that 

 would not yield a sufficient amount by means of small 

 wells. 



Many gardeners in the neighborhood of cities are 

 able to utilize the municipal water-supply, taking advan- 

 tage of the low rates which are granted to large users. 

 Some are able to procure water at a cost as low as 6 

 cents a thousand gallons. This is about as cheap as 

 pumping. 



Many questions arise as to the handling of irrigation- 

 water. The practices have not been worked out nearly 

 so fully in the East as in the West. Almost no well- 

 planned experimental work has been conducted, and 

 opinions among users vary greatly. Although a few 

 prefer to apply water in small amounts and frequently, 

 most seem to think that thorough irrigation is prefera- 

 ble. Most men water at night or when it is cloudy, but 

 some do not hesitate to apply even in midday, thinking 

 that the plants are benefited by the cooling. It is well 

 so to plan the work that the ground will not be muddy 

 at harvesting-time. With tomatoes, precautions must be 

 taken against cracking. This is usually occasioned by 

 heavy watering after the plants have been kept quite 

 dry. Lettuce requires special care to avoid the develop- 

 ment of rots of various sorts. 



The use of irrigation-water does not relieve the 

 grower of the necessity for good drainage or careful 

 conservation of moisture. The former guards against 

 overwatering or heavy rains which may come just 

 after a thorough irrigation. The latter saves water, 

 which is costly and keeps the soil in better physical 

 condition. 



Overhead irrigation systems are used to some extent 

 for spraying, for the application of fertilizers, and for 

 frost protection. In some cases the water is heated 

 before it passes to the nozzle lines. 



It makes little difference how perfect a system of 

 irrigation equipment one may have installed, or how 

 smoothly the pump works, or what a beautiful spray 

 the nozzles throw on the crop if the returns are not 

 sufficient to justify the outlay. This suggestion raises 

 the questions of .cost and of gain in market value of 

 the crop. The first cost for equipping an acre is stated 

 by manufacturers to be in the neighborhhood of 

 $125 to $150, making use of new pipe. Some men have 

 economized in various ways and have achieved the 

 desired result at lower cost, although many figures 

 that are given are misleading because the very impor- 

 tant labor of the owner in installing the system has 

 been neglected. 



It requires 27,152 gallons of water to cover an acre 

 1 inch deep. This amount of water is applied through 

 ^j-inch nozzles at the usual spacings in eight and one- 

 half hours. Water may be pumped ordinarily at 2 to 

 6 cents a thousand gallons. 



Many growers can give very inspiring figures as to 

 the results that they have secured by means of irriga- 

 tion equipment. One well-known New Jersey grower 

 is reported on first-rate authority to have secured 

 twenty-five tons of beets to the acre and 620 bushels 

 of potatoes from the same area. A crop of onions worth 

 $1,500 has been taken off a 5-acre piece early enough 

 to permit a later crop of Golden Self-blanching celery 

 to be matured. Another grower reports that an outlay 

 of $300 to $400 saved several thousand dollars worth 

 of celery, whereas an unwatered acre and a half was a 

 complete failure. 



