IRRIGATION 



IRRIGATION 



1685 



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, and this essential condition is 

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

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

 any moment whether flat tile or common drain-tile are 

 used, except in the quantity of cement required. The 

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

 fectly flat 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 merely to retain the water. 

 Boards or slate are placed outside the cement wall to 

 retain the soil. The tile-bottom may rest on iron or 

 wood cross-pieces. Wood has been in use for this pur- 

 pose at the Ohio Station for twenty years and shows no 

 signs of decay, because it is out of reach of the water. 



Twenty 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 

 same manner as tile-drains, and lengthwise or cross- 

 wise the bed, as preferred. Better results are usually 

 secured if they are laid crosswise than lengthwise, as it 

 is difficult to secure an even flow from long lines of tile. 

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

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

 but not enough to impede the flow of water from the 

 joints. The first tile where the water is introduced is 

 laid at an angle, one end resting on the edge of the 

 bench side. This leaves a wide opening at the first 

 joint, which is closed with cement. A better plan is to 

 use a curved sewer-pipe for the inlet, but this is not 

 always available. The picture (Fig. 1979) shows how 

 the tile is laid on the bench bottom, being a view of a 

 side bench in a carnation-house. 



Following Goff's suggestion in the use of brick, tiles 

 have been used over the entire bench-bottom with good 

 results, and it seems probable that this will be found 

 to be the best form of construction, as it appears 

 more certainly to insure an even distribution of water. 

 The method of construction is the same as above 

 described, for the two plans differ only in the number 

 of tiles employed to distribute the water. When the 

 bench-bottom is covered with tile, placed near enough 

 together so that the soil will not fall between, it will 

 readily be seen that water introduced at any point will 

 flow to all parts of the bed in and around the tile. It 

 needs simply to be brought up to such a level that it 

 will reach the soil, when capillary attraction will com- 

 plete the distribution. Fig. 1980 shows a bench in a 

 tomato house constructed after this plan. A A are the 

 inlets; B the irrigating tile, from which the soil has been 

 removed; C is the tile bench-bottom, covered with 

 cement. The same size of tile, viz., 2%- or 3-inch, is 

 used both above and below. D is the cement side, which 

 has been broken away to show the method of construc- 

 tion. The outer board has been removed also. 



The cost of construction need not be discussed here, 

 except to state that the only items extra, more than are 

 required in any well-constructed greenhouse, are the 

 cement bottom and the tile in which the water is dis- 

 tributed. 



A plan has been devised for applying water to small 

 plants in flats which may properly be mentioned under 

 this head. The flats are shallow boxes with slatted bot- 

 toms. When the plants require water, the flats are 

 placed in a shallow vat of water and allowed to remain 

 until the surface of the soil appears to be damp, or 

 even wet. 



A watering in this manner is far more efficient than 

 by the ordinary method. Taken in connection with 

 sub-irrigation in the benches, a crop of lettuce can be 

 brought to marketable size nearly two weeks earlier 

 than when surface- watering is practised. Anything like 

 a full discussion of results of experiments in watering 

 plants in the greenhouse by sub-irrigation would be too 

 voluminous for an article in this connection. A brief 

 review of the results obtained at some of the stations, 



1980. Sub-irrigation with several rows of tiles. 



together with a short discussion of some general prin- 

 ciples, will serve the purpose intended. The increase in 

 weight of lettuce from sub-irrigated plats over those 

 watered in the ordinary manner has been reported by 

 Rane, as 25 per cent and by Goff and Cranefield as 26 

 per cent. At the Ohio Station the range has been from 

 25 to 100 per cent. In the latter case the result was 

 obtained by commencing with the plants as soon as 

 taken from the seed-bed, and carrying the two lots 

 through to the termination of the experiment, one by 

 watering altogether on the surface of the soil, the other 

 by subirrigation. Each of the experimenters speaks of 

 a gam in earliness of several days, by sub-irrigation. 

 Rane secured similar results with long-rooted radishes 

 by this method of watering, but not with the turnip- 

 rooted sorts, while Munson doubled the crop by water- 

 ing below. Better results have usually been secured at 

 the Ohio Station with the turnip-rooted than with the 

 long varieties, but in all cases there has been a gain in 

 favor of sub-irrigation, varying from 50 to 100 per cent. 

 Rane found that sub-irrigation increased the yield of 

 tomatoes, but the gain was not large. Essentially the 

 same results have been secured in Ohio. The tomato 

 crop has not been greatly influenced by the manner in 

 which the water was applied, and the same is true of 

 beets, while sub-irrigated cucumbers and parsley have 

 shown a decided gain over surface-watered. Carnations, 

 roses, chrysanthemums, sweet peas, violets and smilax 

 have been under experiment by the two methods of 

 watering, and while no such marked results have been 

 secured as with lettuce and radishes, the sub-irrigated 

 plats have shown superiority over those watered in the 

 ordinary manner, in nearly all cases. With carnations 

 the improvement has been mainly in length and stiff- 

 ness of stem. 



Aside from the increase of crop secured by sub-irri- 

 gation, there are other considerations which may be 

 urged in its favor, and these are embodied in the fol- 

 lowing general propositions: 



1. Watering by sub-irrigation in the greenhouse saves 

 labor. The amount of labor saved depends mostly 

 upon the completeness of the arrangements for water- 

 ing, but there is a saving in the number of applications 

 as well. It is possible to reduce the time employed in 

 watering a house, or series of houses, to one-fifth the 

 time usually required. 



