n tile conveys the water.
Beginning at the highest point of the field to be irrigated, a
six-inch (or larger) line of tile should be laid along the highest
ground with a fall of not over one inch to each ten feet. From this
main trunk should be branch lines of "laterals," laid from eight to
twelve feet apart, as they would be laid for draining a field. These
branch lines may be laid at an angle to the main trunk as may be
most convenient; all the joints must be covered so as to keep out
the flirt. The whole system should be laid deep enough in the ground
to be secure from frost; but to be most effective it should not be
over fourteen to sixteen inches below the surface, hence
sub-irrigation cannot be used very successfully in the Northern
states. In a sandy loam soil with a clay subsoil it works best at
sixteen to twenty-four inches.

This is substantially Colonel Waring's method of sewage disposal. To
get the best use of it for plants, the water should be assembled and
kept in the sun for ten to twelve days, then turned into the pipes
until the ground is well soaked, and then shut off and not allowed
in the pipes again for ten to fifteen days, according to the weather
and condition of moisture in the soil. The crop should be cultivated
between each watering.

However, as Bailey says, "Evidently in all regions in which crops
will yield abundantly without irrigation, as in the East, the main
reliance is to be placed on good tillage."

"Most vegetable gardeners in the East do not find it profitable to
irrigate. Now and then a man who has push and the ability to handle
a fine crop to advantage, finds it a very profitable undertaking."
("Principles of Vegetable Gardening," page 174.) Bailey, however,
was not thinking of "overhead irrigation."

The late J. M. Smith, Green Bay, Wisconsin, was one of the expert
market gardeners of his region. "The longer I live," wrote Mr.
Smith, then in the midst of a serious drought, "the more firmly am I
convinced that plenty of manure and then the most complete system of
cultivation make an almost complete protection against ordinary
droughts." (Same, page 330.)

If the soil is cultivated carefully and intensively, it will hold
water within itself and carry a storage reservoir underneath the
growing crop. Finely pulverizing and packing the seed bed, makes it
retain the greatest possible percentage of the moisture that falls,
just as a tumbler full of fine sponge or of birdshot will