26 BULLETIN" 462, U. S. DEPARTMENT OF AGRICULTURE. 



is considered that the maintenance and operation are at an absolute 

 minimum, it may be seen that the Sanford system of irrigation is 

 satisfactoiy where conditions discussed above are favorable. 



OTHER FORMS OF SUBIRRIGATION IX FLORIDA. 



Several other localities use the tile systems for irrigation and 

 drainage. Several hundred acres in the Manatee trucking sections 

 are irrigated by this method, as are about 200 acres along the shores 

 of Lake Apopka in Orange County. 



Most of the tiling in these localities is similar to the systems 

 described for Sanford, although there are exceptions. Some of the 

 Manatee farmers use boards nailed in V-f orm instead of tiling. This 

 is done in soft, springy lands where it is hard to keep tiling in align- 

 ment. It is doubtful if boards should be used even in such soft 

 ground, and a common practice among drainage men is to lay ordi- 

 nary clay tiling upon a single board placed in the bottom of the 

 trench where the soil conditions are not favorable for tiling alone. 

 The boards will rot out in about 10 years, while good tiling will last 

 much longer, although it needs to be cleaned out occasionally. 



The contour methods of subirrigation are practiced mostly along 

 Lake Apopka, where the grades are too steep for the ordinary 

 methods. Much of the trucking section here is in a narrow strip 

 along the lake and some of the grades are quite steep, the land 

 having a fall of several feet per hundred. Flowing wells are ob- 

 tained at the lower levels on most of the farms, but they will not 

 force the water to the top of the main, consequently it is common to 

 install a small engine and low-pressure pump to act as a booster. 



There are also isolated cases where there is no impervious sub- 

 stratum of hardpan to permit successful subirrigation. Such farms 

 have a water plane standing within 3 or 4 feet of the ground surface 

 and this saturated soil seems to act as a hardpan, preventing the loss 

 of irrigation water. These instances prove conclusively, in the 

 writer's opinion, that capillary attraction does not play an all- 

 important part in the subirrigation of the sandy soils of Florida, for 

 were this the case it would not be necessary to irrigate garden prod- 

 ucts when the soil 3 feet below the surface is saturated. 



OPEN-DITCH SX'BIREIGATION AT HASTINGS. 



Another method of subirrigation is that practiced in the potato 

 district near Hastings. This is the largest irrigated area in the 

 State, consisting of about 10,000 acres, of which 7,000 acres are in 

 St. Johns County and 3,000 in Putnam County, all within the 

 so-called Hastings district. Probably two-thirds of the potato crop 

 in this territory is irrigated, practically all by the open-ditch method. 



