898 
a thick, close, nearly impervious clay 
subsoil. 
5. Lands like rice lands, water mead- 
ows and cranberry marshes, where water 
is applied excessively and must be remov- 
ed again. 
In general, all low-lying fine-grained 
soils with fine, heavy subsoil will need 
drainage. 
Benefits of Drainage 
1. Removes excessive water. 2. I[n- 
creases the capillary supply of moisture. 
38. Improves the texture. 4, Increases 
the root pasturage. 5. Affords better air 
circulation. 6. Makes the soil warmer. 
7 Lengthens the growing season; firms 
the soil. 8. Assists decay and nitrifica- 
tion. 9. Prevents erosion. 10. Dimin- 
ishes the effect of drought. 11. Prevents 
heaving. 12. Prevents the rise of alkali. 
Drainage does this and more. It pays in 
increased yields and land values. Road 
drainage aids in transportation. Sani- 
tary drainage improves healthfulness. To 
what extent drainage is warranted de- 
pends on the crops to be grown. 
Kinds of Drainage 
1. Natural drainage. (a) Through gravel 
subsoil (b) Through surface run-off. 
2. Artificial, (a) Open drains. (b) 
Underdrains (brush, stone, box for alkali 
and tile). 
The object of underdrains is to assist 
the action of gravity. Both surface and 
underdrains have their field for useful- 
ness. 
A. Open drains or surface drains are 
essential auxiliaries to tile for drainage 
of large areas. They remove water from 
the surface and also from the subsoil. 
The amount removed from the subsoil 
depends upon their depth and fall and the 
amount of water in the channel. Surface 
they are adapted to: 1. Where the volume 
to be removed is large. 2. Where the water 
table is near the surface. 3. Where the 
drainage is designed to be only for a 
short time. 4. As a supplement to tile 
drainage for large areas of flat land. 
The efficiency of open drains depends 
on the surface flow of water into the 
channel. A double plow should be used 
to make dead furrows that will serve as 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
surface drains and as temporary stor- 
age for excessive water. In order to 
drain the subsoil the ditch must be deep 
enough to permit percolation from the 
adjacent subsoil and the efficiency will 
depend on the texture and structure of 
the subsoil 
To be effective, an open drain must be 
evenly graded and have a smooth bottom 
and sides, and these side walls must be 
staple. A semi-circular form will give 
the greatest carrying capacity per cross- 
sectional area, and will have the least 
surface friction. Usually the bottom will 
be made flat, however, and will be about 
one-half the width of the top. The slope 
of the wall will vary with the soil. One 
to one slope is commonly used with clay, 
and one and a half to one for loam soils. 
Lighter soils will stand a deeper grade. 
The fall should be uniform and just suf- 
ficient to afford scouring without erosion 
or silting. Silt or sand is more sus- 
ceptible to erosion than clay. Sedimenta- 
tion will be less where growth of vegeta- 
tion in the bottom is prevented. 
When it is desired to reclaim and im- 
prove large areas of level land such 
tracts must be cut up into sections or 
districts by large open ditches, in order 
that tile drains may be laid in every part 
without necessitating the use of mains 
too large and costly to be profitable. 
While these open ditches are not desir- 
able in themselves, since they occupy the 
land and divide the field into irregular 
shapes, yet they are necessary to every 
large system of drainage. They should 
be located with care, following the course 
of natural drainage as far as possible, 
with due regard to straight courses. 
Construction of Ditches 
A common method of making small 
open ditches is to use a team and scrap- 
er. This is a good method to use where 
the earth is dry enough to afford a foot- 
ing. Contractors have done such work 
for as low as ten cents per cubic yard, 
where conditions were favorable. A. 
large part of the open ditch work must 
be done in swamps, and where it is too 
wet to use a team and scraper. 
For the construction of small and shal- 
