908 
6. Laying out and supermiending, 5 
per cent. 
Tile required per acre if laid parallel 
and 50 feet apart will be 872 feet. Cal- 
culate the cost of such thorough drain- 
age per acre of 4-inch tile. 
Benefits 
1. Cause Firmness and Fineness of the 
Sowl.—The excess of water recedes from 
the surface and takes its place lower in 
the soil, soon leaving a firm surface, 
which can be passed over by teams or 
live stock without injuring the texture. 
The fineness of the soil is increased by 
percolation. 
2. Permits Earlier and More Timely 
Cultivation.—The water from rains and 
thawing ice passes down through the 
soil, admitting warm air and rains, so 
that the surface is ready for early plants 
much sooner than wet soils. 
3. Produces Aeration of Soil.—The 
interspaces of soil becoming relieved of 
water are filled with air which carries 
fertilizing gases and furnishes oxygen to 
the roots of the plants and for the sup- 
port of soil bacteria. 
4, Increases the Temperature of the 
Soil.—This is explained in King’s book 
on “The Soil.” If we allow the surplus 
water to drain away from the field rapid- 
ly, rather than to hold it there until it 
has time to evaporate, it will greatly 
favor the warming of the soil. 
5. Prevents a large waste of fertility 
by surface washing. 
6. Increases the depth of the soil. 
Approximate Prices and Weights of Tile 
Weight Average 
Price per car- No. of 
Sizein per1,000  footin loadin feet 
inches feet pounds feet per ton 
3 $ 16 VY, 7,500 400 
4 614 6,50 334 
5 30 9 :000 250 
6 40 11% 4,000 182 
T 50 14 000 1438 
8 60 18 2,400 111 
10 90 25 ,600 80 
12 120 33 ,000 60 
14, 150 43 800 56 
16 190-220 62 500 BR 
18 265-300 80 400 27 
24. 450-526 120 300 18 
EF. E. Jones, 
New Westminster, B C 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
DRAINAGE OF IRRIGATED LANDS 
WALTER W. WEIR 
Drainage Engineer 
The drainage of irrigated lands has 
become a problem whose magnitude al- 
most equals that of irrigation itself. 
Fully 30 per cent of the irrigated land 
of the United States could be benefited 
by drainage or by some of the preventive 
measures which are used to stop seepage 
from canals and laterals. 
Probably the most important reason 
why irrigated land needs drainage is that 
irrigation is an unnatural condition for 
most of the irrigated soils. These soils 
have no natural drainage, the capillary 
drainage channels that are found in the 
soils of humid sections are often entirely 
lacking because there has been no water 
to form them. The soil does not adjust 
itself to these conditions readily and con- 
sequently artificial drainage is necessary. 
Another reason for irrigated lands 
needing drainage is that often very large 
amounts of water are used in a compara- 
tively short time. It is not at all un- 
usual to learn that 5 to 10 or even 15 
acre feet of water are being used during a 
single season. Only a very small part 
of this is actually used in the growing of 
plants and the remainder either is lost 
by evaporation or seeps into the ground 
probably to appear at some lower level. 
A. third cause for damage is the pres- 
ence of hard-pan streaks in the soil which 
prevents the percolation of water in the 
directions it would naturally take. These 
impervious strata may hold the water 
table so close to the surface that damage 
is done or it may form pockets which col- 
lect water, or again it may form a pas- 
sage for the excessive seepage of a canal 
or lateral. 
All soils in arid regions contain alkali 
to a greater or less degree depending on 
the degree of natural drainage which the 
soil has. Gravelly soils which have bet- 
ter drainage than the deep volcanic ash 
soils seldom develop bad alkaline condi- 
tions such as are often found in the deep- 
er soils. Alkali is a broad term used to 
cover all of the injurious salts, the most 
common of which are the sulphates, chlor- 
