34 BULLETIN 355, U. S. DEPARTMENT OF AGRICULTURE. 
Surface drainage (Ref. No. 8, pp. 7-9). — In the removal of surface 
water it is ordinarily necessary to use open ditches of sufficient size 
to carry the water coming to the drained land from adjacent terri- 
tory. The size of the ditch necessary in such a case can be approxi- 
mately estimated by observing the flow of water following a severe 
freshet. When the surface water from large areas is to be carried 
away it is best to secure the services of an engineer who, after mak- 
ing the necessary survey of the area to be drained, can compute the 
size of the ditch necessary. 
In the case of comparatively level land, where it is impossible to 
establish an outlet for subsurface drainage, surface drainage should 
be made as effective as possible. This is especially necessary where 
the land is underlain by an impervious clay subsoil. It is often 
practical to use the common plow in ditching such level areas. The 
plowing should be done in long narrow lands, and the dead furrows 
should be carefully cleaned out to serve as drainage ditches. It is 
frequently necessary to cut ditches across from one dead furrow to 
another in order to drain a slight depression which would otherwise 
be filled with water. These narrow plow lands should usually be 
kept in the same position for two or three years in order to round up 
the back furrow somewhat and deepen the dead furrow, but they 
can not be kept longer than three years ordinarily without widening 
the dead furrow to an undesirable extent. After this the plowing 
must be reversed, and the first two furrows of the lands turned into 
the dead furrows. This method of surface drainage has its greatest 
objection, perhaps, in the difficulty which comes from working over 
the open-furrow ditches. 
The timely use of a shovel or large hoe in the spring will greatly 
aid in removing the surface water coming from rain and melting snow. 
Subsurface or under drainage (Ref. No. 8, pp. 27-34). — Practically 
all underdrainage is now accomplished through the use of common 
porous clay tile or glazed tile, laid loose jointed so that the water 
may pass into the drains through the joints or where the tile meet. 
The glazed tile are usually more expensive than the porous, but they 
are also more durable. Factors of greatest importance to be deter- 
mined in planning an underdrainage system are (1) depth at which 
the tile should be placed, (2) the available fall or grade of the tile, 
(3) the system to be used, (4) the distance apart of tile lines or laterals, 
and (5) the size of tile to be used. 
Depth. — The depth for placing tile is dependent upon several 
things. First of all, tile must always be placed below the depth of 
tillage and also below the frost line. Freezing will crumble porous 
tile, and it causes heaving of the ground and displacement of the tile 
in any case. The depth to which tile should be placed varies also 
with the type of soil and the desired depth of water table. The 
