IRRIGATION IN FLORIDA. 27 
This section is very similar to the Sanford trucking district, both 
as to its soil conditions and its water supply. The ground surface in 
general is very level and the soil is of the flatwoods variety, inter- 
spersed with patches of low hammock lands. The highest elevation 
is about 17 feet above sea level, the average being about 10 feet. 
The potato lands are underlain with an impervious stratum or hard- 
pan at depths varying from 20 inches to 5 feet. 
The water supply is from flowing artesian wells (PL III, fig. 1), 
the average depth of which is about 200 feet. Some of the wells give 
a good flow at 110 feet, while others are nearly 400 feet deep. Most 
of them are 4 inches in diameter ; the diameter of the average San- 
ford well is 2 inches. A good 4-inch well will supply about 300 
gallons per minute. The cost of the wells increases with the depth, 
the average cost being about $200 to $300, or $1.50 to $2 per foot, 
complete. 
In most cases water is applied to the crops through open field 
ditches placed in parallel rows 30 to 40 feet apart. (PL III, fig. 2.) 
These ditches are fed by a main ditch which runs at right angles 
to them. The dimensions of this vary somewhat, but it usually is 
about 2 feet on the bottom, 1J to 2 feet deep, and 7 to 10 feet wide 
on the top. The slope often is gradual enough to accommodate a 
row of potatoes along the banks. The head ditch in the average farm 
is a partnership affair running along the road, and is used as a 
general drainage ditch when necessary. 
The water runs from flowing wells into the main head ditch, from 
which it is led into the field ditch. The water is controlled from the 
main to the laterals by simple wooden gates, or, in some cases, by 
temporary dirt embankments thrown up with a shovel. As at San- 
ford, the grades are very slight and the head of water often is relied 
upon to force a flow. The process of irrigation consists of filling the 
field ditches and keeping them so until the soil between them has 
become subirrigated. The action is essentially the same as that 
at Sanford, the open ditches merely taking the place of the under- 
ground tile. 
The amount of water needed per irrigation by this system and the 
time required depend upon the amount of moisture in the soil. Gen- 
erally a 4-inch well flowing 300 gallons per minute will irrigate 40 
acres. In times of protracted drought the well is run continuously, 
one well taking care of 40 acres. The need for one 4-inch well on 
every 40- a ere piece is accepted generally. If the flow is 300 gallons 
per minute, this means a duty of water of 1\ gallons per minute per 
acre. This is not far from the amount allowed for some of the 
irrigation systems of the West. The time of irrigation depends upon 
the rainfall. No irrigation is needed in some years, while in others 
water is required during a large part of the growing season. 
