22 BULLETIN 462, IT. S. DEPARTMENT OF AGRICULTURE. 
nearer the inlet side of the box, making the chamber on the outlet side large 
enough to admit the hand easily to operate the plugs. For this purpose cypress 
plugs are often used. One of these consists of a large hollow plug fitted to the 
opening and a smaller solid plug which fits the hole in the larger plug. By 
this arrangement different sized streams can be obtained. The plugs often 
become water-soaked, making it difficult to remove them. Sliding galvanized- 
iron gates would be preferable. 
The tools used in excavating and installing the tile are shown in figure 3 of 
Plate II. The mattock and ax are used for cutting the roots in the newly 
cleared land. The wide irrigation shovel is used for removing the topsoil and 
the curved adjustable shovel for cleaning out and forming the bottoms of the 
trenches. 
The cost of the Sanford tile system ranges from $100 to $125 per acre, not 
including the water supply or drainage outlet from the field. 
In the operation of the Sanford system water is turned into the main feed 
pipes and divided among a number of laterals by operating the intake plugs. 
The plugs in each pocket are adjusted so that the water will be backed up in 
certain sections and held there until the moisture meets between the tile lines. 
The water issues from the tile joints into the porous sandy subsoil and follows 
along on top of the impervious substratum until the surface-soil area is under- 
lain with a sheet of water. If irrigation continues after this state has been 
reached the water will soon show on the surface. 
Irrigation is begun when the first winter crops are planted in the fall. The 
ground is completely saturated to the surface to settle the young plants into 
place and give them a start. The common practice is to irrigate every 10 days 
to 2 weeks during the growth of the crop, depending upon the rains which occa- 
sionally occur during the winter season. Celery is irrigated 24 hours before 
cutting. This is thought to swell the plants and make them brighter and 
heavier. 
The length of time required to saturate the Sanford soils varies greatly on 
the different farms. Some farmers use a large head from a number of wells, 
forcing the water into both ends of level laterals, thus causing saturation within 
a few hours. Others use smaller amounts of water and take 12 to 48 hours to 
irrigate. The amount of moisture contained in the soil prior to irrigation and 
the depth to hardpan determine materially the length of time necessary for 
saturation. It also takes longer to subirrigate a field on which a cover crop 
has been turned. Likewise, a soil finely pulverized is slower to irrigate than 
one that has not been cultivated. 
Overirrigation is a common practice, and probably is more expensive than 
is commonly realized. On opening the tile lines to drain off the excess water 
large quantities of the fertilizing constituents applied in commercial fertilizers 
are carried away. This has taught the farmers in this section the need of 
applying fertilizers immediately following a heavy rain. 
There are special cases about Sanford deserving of mention which 
have not been touched upon in the above discussion. Systems for the 
subirrigation of the fields adjacent to the river which have heavy 
grades should be laid out somewhat differently from those described 
above. If the mains were laid on the high side of the field and the 
laterals allowed to run down the slope having a grade of several feet 
per hundred, the water would not have sufficient opportunity to per- 
form its task of irrigating the ground between the lines. In sucl) a 
