THE BEET-SUGAR INDUSTRY IN 1920. 25 
Seepage from ditches. — It is sometimes necessary to construct 
irrigating ditches higher than the surrounding area, to carry the 
water across low places or to carry it long distances. It is very 
common for the water to seep through the ditch bank in such cases 
and to saturate the surrounding fields, especially if the soil in those 
fields has a high water-holding capacity. Ditches constructed of 
clay or other close-textured material allow less seepage than ditches 
constructed of sandy or other porous material. In the case of 
sandy ditches the holding capacity may be increased very greatly 
by oiling the surface of the ditch with crude oil ; this can be applied 
economically only in those localities not far removed from the source 
of oil supply. Where the oil is available it may be spread over 
the inner surface of the ditch when the ditch is empty and should 
be allowed to soak into the soil before the water is turned into the 
ditch. A second or even a third application of the oil will improve 
the condition of the ditch. Ditches treated in this manner will 
carry water with almost no seepage, and when the work is done 
properly the oiled surface will frequently last for several years. 
If the oil is spread over the ditch bank, weed growth will be pre- 
vented, or at least decidedly retarded. There is always some seep- 
age from the ordinary untreated earth ditch, and the amount of 
damage done by this seepage will depend upon the nature of the 
ditch and the soil of the adjacent fields. The seeped areas may 
sometimes be rendered tillable by drainage. 
Seepage from earth reservoirs. — The area of land damaged by 
seepage from earth reservoirs is less than that from ditches, but 
the total is considerable and is usually progressive; that is, a small 
area first appears to be water-logged and this gradually increases 
from year to year until large areas involving fields and sometimes 
entire farms are destroyed. Seepage from reservoirs depends upon 
the construction of the reservoir and upon the nature of the sur- 
rounding country. Reservoirs are sometimes constructed in moun- 
tainous areas for the purpose of catching and storing flood waters 
due to -melting snows. Generally the location of these reservoirs is 
such that no tillable soil is injured through seepage; the only loss 
in such cases is caused by the quantity of water which seeps away 
and becomes unavailable for irrigation purposes. In other instances 
reservoirs are constructed of cement, which is nearly impervious to 
water, and consequently little or no loss from seepage results. The 
serious injury due to seepage from reservoirs takes place in those 
localities in which the reservoirs are constructed entirely or in part 
of earth and in which the surrounding country is composed of tillable 
land; in such cases the loss due to seepage is sometimes of con- 
siderable importance. 
Alkali. — As already indicated, one of the serious results of seepage 
is the accumulation of alkali in the surface soil. In such cases 
