40 BULLETIN 462, U. S. DEPARTMENT OF AGRICULTURE. 
raphy of the grove is flat to gently rolling, the highest elevation 
being not more than 10 or 12 feet above sea level. The surface soil is 
light and sandy in some parts and a good quality of low hammock in 
others, the latter type being very light and porous. The soil is shal- 
low over all the grove, there being a substratum of rock or hardpan 
under nearly the entire grove. The depth of this substratum varies, 
averaging about 20 inches beneath the surface. On account of the 
low character of the ground the trees are grown on ridges to prevent 
flooding out during periods of excessive rains. 
Xotwithstanding the low-lying topography and the frequent need 
of drainage due to excessive rainfall, there often is a very serious 
need for irrigation. This is caused mainly by the long periods of 
drought, but is partly due, also, to the extreme shallowness of the 
soil, since the moisture absorbed by the trees can not be replenished 
from below on account of the layer of impervious rock. 
The water supply for the irrigation of this grove is obtained from 
two 6-inch artesian wells. Each well is about 600 feet in depth, 
and when allowed to flow freely will supply about 400 gallons per 
minute, exerting a pressure of 7 pounds per square inch when capped. 
Several patches of garden vegetables scattered through the grove 
are watered by the wells at their natural pressure. When it is 
necessary to irrigate the grove this pressure is supplemented by a 
2-stage horizontal pump having a capacity of TOO gallons per minute 
and operated b} 7 a 50-horsepower gasoline engine. 
The distribution system consists of about 33 miles of iron pipe, 
varying from 1 inch to 6 inches. A 6-inch main delivers the water 
to laterals varying in size from 4 inches at the main to 1J inches at 
the ends. The laterals, which run parallel to each other, are placed 
along every fourth row of trees, the tree rows being 25 feet apart. 
One-inch pipe uprights are connected to the laterals at intervals of 
100 feet. The hydrants are placed under trees and stand about 2 
feet above the ground on the 1-inch pipe uprights. 
In connection with this system there are 50 pieces of 1-inch 
garden hose, each about 50 feet long, and 50 movable sprinklers, 
each sprinkler being attached to about 6 feet of 1-inch pipe. This 
pipe is sharpened at one end and has the nozzle at the other, with 
a hose connection about 1 foot from the bottom. "When in use the 
sharpened end of the pipe is pushed into the ground and the appa- 
ratus is connected by hose to a convenient hydrant. The pipe thus 
stands upright, delivering a spray of water through the nozzle, and, 
in this position, may be left temporarily while other pipes are being 
set up. 
Fifty of these nozzles are in operation when irrigation is in full 
force. Each nozzle is placed in the center of the square formed by 
four trees, the spray watering one side of each tree when in a single 
