158 VEGETABLE FORCING 
be considered: First, the tile lines must be laid level, and, 
second, there must be water-tight walls around the beds, 
which may be of any convenient size. Beds need not be 
more than 6 inches deep, though 8 to 10 inches will give 
better results, and some growers prefer them even deeper 
than 10 inches. 
Pipes of various sizes may be used, but tile are more 
satisfactory as well as more economical. Tile 2% inches 
in diameter are preferred if they must be laid near the 
surface of the beds, and 38-inch size is best if they are to 
be placed 4 or 5 inches or more below the surface of the 
ground. In shallow beds the tile need not be covered with 
more than an inch or two of soil. If the soil is light, open 
and porous, it is better to place the tile near the surface 
of the beds rather than at a depth of 10 inches or more, 
because less water will be required. In shallow beds of 
light soil, the first line of tile should be 10 inches from 
the wall of the bed, and the interior lines should be about 
214 feet apart, though 3 feet is permissible. In the 
deeper beds it is customary to place tile 18 inches to 2 
feet apart.. The concrete walls, if well made, need not be 
more than 2% inches thick. 
A little mud mortar placed at each joint will hold the 
tile in place while they are being laid and until the beds 
have been filled with soil. Deep beds require more water 
than shallow ones, but applications need not be so fre- 
quent. There does not seem to be any uniform practice 
in regard to the length of the lines of tile. If they are 
carefully placed, with the joints as close together as 
possible, and there is an abundant flow of water, the lines 
may be 50 feet long. At the ends of such lines, elbows 
are used to provide outlets above the surface of the 
ground, and pipe headers may be used to connect with 
several lines of tile. It is then possible to water a 9 x 50 
bed in five hours or less, the time depending upon the 
