IKRIGATION 



joints. The first tile wbere 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. 1182) 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 



IRRIGATION 



835 



1183. Sub-irrieation with two tiers of tile. 



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 de- 

 scribed, 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 be 

 readily 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 complete the dis- 

 tribution. Fig. 1183 shows a bench in a tomato house 

 constructed after this plan. AA 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 construction. 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 practiced. 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, 

 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. of West Virginia, as 25 per cent and by Goff and 

 Cranefleld as 26 per cent. At the Ohio Station the 

 range has been from 2.5 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 experi- 

 ment, one by watering altogether on the surface of the 

 soil, the other by sub-irrigation. Each of the experi- 

 menters speaks of a gain in earliuess 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, of 

 Maine, doubled the crop by watering below. Better re- 

 sults 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-irriga- 

 tion, 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 suh- 

 irrigated cucumbers and parsley have shown a decided 

 gain over surface-watered. Carnations, roses, chrysan- 

 themums, sweet peas, violets and smilax have been un- 

 der experiment by the two methods of watering, and 

 while no such marked results have been secured as with 

 lettuce and radishes, the sub-irrigated plots have shown 

 superiority over those watered in the ordinary manner, 

 m nearly all cases. With carnations the improvement 

 has been mainly in length and stiffness 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 follow- 

 ing general propositions: 



(1) Watering by sub-irrigation in the greenhouse 

 saves labor. The amount of labor saved depends 

 mostly on tht completeness of the arrangements for 

 watering, but there is a saving in the number of appli- 

 cations as well. It is possible to reduce the time em- 

 ployed in watering a house, or series of houses, to one- 

 fifth the time usually required. 



(2) Watering by sub-irrigation assures an abundant 

 and uniform supply of wafer to alt parts of the bed. 

 Perfect construction of the benches is assumed in thi.s 

 case, but with such construction watering becomes al- 

 most automatic, the only care necessary being to look 

 after such portions of the beds as may, by position, be 

 subject to unusual conditions of air or sunlight. 



(3) Where sub-irrigation is practiced in the green- 

 house, the surface of the soil does not become compacted, 

 but retains its original loose, friable condition. It is 

 true that where frequent syringing is practiced the sur- 

 face of the soil becomes more or less hardened, but not 

 to the extent that occurs in surface-watering, and the 

 condition is easily remedied, whereas in the other case 

 it is not. It follows that a heavier soil may he used fcir 

 sub-irrigation than with surface-watering. 



Still other considerations might be urged in favor of 

 this method of watering, but many of them would apply 

 to special cases only. Regarding the effect of the 

 method upon insects and diseases, but little can be 

 said. Lettuce rot is less prevalent upon sub-irrigated 

 plots than upon those which are surface-watered, but in 

 extreme cases plants succumb to the disease, whichever 

 method of watering is practiced. Munson found that 

 radishes suffered more from the attacks of millipedes 

 upon sub-irrigated plots than upon plots watered in the 

 usual manner. Nematodes work upon the roots of 

 roses, whichever way the plants are watered. The man- 

 ner of watering has no apparent effect upon the red 

 spider. Even in houses watered wholly by sub-irriga- 

 tion this pest is no worse than in houses "in which the wa- 

 ter is applied to the surface of the soil. It may be said, 

 however, that nearly all classes of plants are more easily 

 kept in a healthy growing condition, and are thus better 

 able to resist enemies of all sorts, when sub-irrigated 

 than when supplied with water in the ordinary way. 



This method of applying water to plants in green- 

 house benches has now been sufficiently tested to de- 

 termine its value. All that now remains is to devise 

 ways and means to utilize what is known concerning it. 

 The adaptation to suit particular cases must be made by 

 individuals, but this will be far easier in the future 

 than in the past, because better methods of construction 

 prevail than formerly. The success of sub-irrigation in 

 the greenhouse is now simply a question of mechanics. 

 W. J. Green. 



