IRRIGATION IN FLORIDA. 37 
ting young plants. This advantage is of more consequence in Florida 
than in the more northern States on account of the exceedingly sandy 
nature of most of the surface soils. The rapidity with which these 
soils dry out makes frequent irrigation necessary in dry weather, and 
this can be done easily with the overhead system without wasting 
water below the root area. It is necessary to fertilize most of the 
truck crops in Florida very often in order to assure rapid growth, 
but fertilizer is of little effect if the surface soil is dry. The over- 
head system dissolves this plant food and makes it effective in a short 
time. As has been pointed out already its value as a protection 
against frost has not been thoroughly demonstrated in all parts 
of the State but there are many overhead systems which are used 
successfully for frost protection, especially in the southern section. 
The use of spray systems for washing off dust and certain lice from 
plants is advocated by some, and the application of certain insecti- 
cides through the pipe lines has been suggested, but so far as the 
writer is aware this has not been attempted in Florida. 
The disadvantage of this system lies primarily in its high cost of 
construction. An outlay of $200 to $500 per acre is heavy and means 
that the application of the water must bring in additional income 
above the cost of maintenance and yearly interest on the first outlay. 
The cost of operation is very light in most cases, averaging not more 
than $3 to $5 per acre per year for fuel. Labor cost of irrigation 
may be neglected for the small plant, and most of them are small. 
Depreciation of engine and pipes may be estimated at 7 to 10 per 
cent, and if repairs are considered, the higher figure should be taken. 
Interest charges are high in Florida, and should not be put under 7 
per cent. Thus, if a plant cost $300 per acre, including entire sys- 
tem and well, the annual interest charges would be $21, depreciation 
about $30, and operating expenses, not including labor, about $5, or 
a total of $56 per acre. Thus it is seen that in order to come out even 
on his investment the farmer must make $56 per acre more on his 
irrigated crop than he would if the crop were unirrigated; and 
he must do this every year, as it will cost nearly as much to keep the 
plant during a rainy season as during a dry one, since only oper- 
ating expenses are low in a rainy season. 
It was shown under the discussion of the Sanford subirrigation 
systems that the cost of growing some of the truck crops is very 
heavy, even though no irrigation is considered. This is true through- 
out the State. Sometimes large profits are made without irrigation, 
but, again, heavy losses are sustained in times of drought. This pos- 
sibility of loss is what should determine the permissible cost of an 
irrigation plant, and most of the owners of overhead irrigation 
plants claim that the plants pay; some say they do not, while a 
large number admit that they do not know. It is easy to see, 
