834 



IRRIGIATION 



IRRIGATION 



throwing up slight ridges, with a plow or other imple- 

 meut, and the water turned into these basins in succes- 

 sion and allowed to accumulate to a suBicieiit extent. 

 This method is particularly applicable to fruit trees, 

 although it is occasionally used in other crops. In very 

 sandy soils the water is occasionally carried through 

 the field in wooden troughs, which admit of sufflcient 

 seepage to water the land. This prevents the undue 

 seepage which might occur in such soils if the water was 

 tiowed over the surface. Another method is to dis- 

 tribute the water through the field in iron pipes, with 

 openings at frequent intervals, in which nozzles can be 

 attached to deliver a fine spray over a small area. With 

 four or five such nozzles an attendant can water a con- 

 siderable area of ground in the course of a day. Such 

 an irrigating outfit in Florida was supplied 'with a 

 power equivalent to about one horse-power per acre. 

 The mains and laterals were of 1-inch or l.S-inch iron 

 pipes laid near the surface of the ground, the laterals 

 about 100 feet apart, with hydrants every 50 feet. 

 Tanks were originally used, but it was found desirable 

 to pump directly into the mains to insure a sufficient 

 pressure. 



Care should be exercised in applying water to the 

 land. Where water is plentiful there is a common prac- 

 tice of using such an excess as to injure the Havor of 

 fruit, increase the liability of disease, and eventually in- 

 jure the land bj'the accumtilation of seepage waters and 

 of alkali. As a rule, there has been very much more 

 damage from over- irrigation than from the use of too 

 little water. The first two or three years a soil usually 

 requires a considerable amount of water, but after be- 

 coming well moistened to a considerable depth it should 

 require comparatively little water thereafter to maintain 

 its fertility. As it is not easy to apply just the proper 

 amount, the excess should be provided for. If there is 

 any reason to fear lack of drainage, the land should be 

 thoroughly underdrained before Irrigation is started, or 

 at any subsequent time when the need of it becomes 

 apparent. 



Irrigation always should be supplemented by the 

 ■most thorough cultivation. After going to the expense 

 of watering the soil in this way, it is poor economy to 

 allow the water to escape by evaporation or otherwise; 

 therefore every precaution should be used in thorough, 

 subsequent cultivation and in the exclusion of weeds, 

 to conserve the moisture so applied. The intelligent 

 horticulturist will find that in the use of this expensive 

 method of maintaining a proper water supply in the 

 soil, it is incumbent upon him, even more than if the 

 method were not used, to give careful attention to all 

 the ordinary methods of preparation and cultivation in 

 oriler to maintain the advantages he has established by 

 the Irrigation plant. Milton Whitney. 



Sub-irrigation in the Greenhouse. — The term sub- 

 irrigation is used to describe a method of supplying 

 water to the roots of plants by means of some form of 

 conduit placed below the surface of the soil. In green- 

 house operations, the essential features of the plan are 

 a level, water-tight bench-bottom, and tile or pipes to 

 serve as conduits for the water. The tile, or pipes, are 

 laid directly on the bench bottom, and over these the 

 soil is spread, usually to the depth of about 6 inches. 

 When water is introduced in suflicient quantities 

 through the tile or pipes, it passes out at the joints or 

 perforations into the soil. 



When applied to greenhouse operations, the term sub- 

 watering has been proposed by Goff ami Cranefield for 

 the reason that Irrigation is used to denote watering on a 

 large scale out-of doors. It may be said, however, th.at 

 the words watering and Irrigation do not indicate the 

 scale of operations with any degree of accuracy, hence 

 it seems as well to use an old word as to coin one, es- 

 pecially when the familiar word expresses the meaning 

 intended. 



Experiments in watering plants by this method were 

 begun in the winter of 1890 and 1891, at the Ohio Ex- 

 periment Station. The suggestion came from the re- 

 sult obtained in an effort to cheek the lettuce rot. Water 

 was introduced to the soil in boxes by means of a pipe, 

 in a similar manner to the method often employed in 

 watering hills of melons and cucumbers. When the 

 plants were watered in this manner, the lettuce showed 



so much more vigor than that watered in the ordinal y 

 way that operations were begun at once on a larger scale . 

 first in a bed on the ground having a clay bottom, i^en 

 on a water-tight bench, made of Imnber, and finally on 

 tile benches, covered with cement. 



In all of the earlier experiments the water was intro- 

 duced through pipes, or drain-tile, laid about 2 feet apart 

 on the bottom of the benches. Goff and Cranefield have 

 used brick instead of tile, placing them near enough to- 

 gether to touch. They were set on edge in a galvanized- 

 iron pan, made for the purpose. J. C Arthur clipped off 

 the corners of the bricks, so as to facilitate the flow of 

 water. The Ohio Station has modified this plan by using 

 common drain-tile, laid so as to touch, thus covering 

 the entire bench bottom, instead of a line of tile evei'y 



2 feet, as at first. 



Benches made of lumber have proved unsatisfactory 

 because of the swelling and warpin;: df tin* boards. 

 Solid beds on the ground have lu-t li. en vmrrssful, ex- 

 cept where an impervious clay b"ttiiiii i xi^i. .1. Galva- 

 nized-iron adds greatly to the cost uf cuu.st ruction, and 

 lasts only a short time. The only suitable bench for 

 greenhouse sub-irrigation is one made of materials 

 which are not acted upon by water. 



A well-made tile- and cement-bench seems to be the 

 only form of construction that will meet the require- 

 ments. Such a bench does not cost so much as to pre- 

 clude its use, and will last as long as any other part of 

 the greenhouse. In describing such a bench, it will not 

 be necessary to enter into details, except such as relate 

 to the method of watering under discussion. The bench 

 must be water-tight, or nearly so, and this condition is 

 secured by spreading a layer of cement, an inch or more 

 in thickness, over the tile bottom. It is not a matter oi; 

 any moment whether flat tile or common drairf-tile are 

 used, except in the quantity of cement required. The 

 cement must be spread with care, so as to secure a per- 

 fectly fiat, level bottom, otherwise the water will not 

 flow uniformly in all directions. The sides of the 

 benches are made of cement also, but need be only 2 or 



3 inches high, or of sufficient height to merely retain 

 the water. Boards or slate are placed outside the ce- 

 ment wall to retain the soil. The tile-bottom may rest 

 on iron or wood cross-pieces. Wood has been in use 

 for this purpose at the Ohio Station for seven years and 

 shows no signs of decay, because it is out of reach of 

 the water. 



Nine years' experience shows that a perfectly con- 

 structed bench bottom, with the tile laid 2 feet apart, 

 will serve satisfactorily in distributing the water to all 

 parts of the bed, provided the tile are straight, so as not 

 to impede the flow of water. The tile are laid in the 



■igat 



of tile. 



same manner as tile-drains, and lengthwise or crosswise 

 the bed, as preferred. Better results are usually se- 

 cured if they are laid crosswise than lengthwise, as it is 

 difficult to secure an even flow through long lines of tile. 

 A little cement or mortar is used at each joint merely to 

 hold the tile in place when the soil is put in the bench, 

 but not enough to impede the flow of tvater from the 



