IRRIGATION IN" FLORIDA. 59 



size and capacity of the pumping unit. The crop to be raised also 

 must be taken into account, as must the methods which will be em- 

 ployed in distributing water. If the water supply is adequate and 

 a 100-acre grove is to be irrigated it is evident that the plant should 

 be of such capacity as to irrigate the whole grove within a reasonable 

 time in order to obtain maximum service from the plant. This is 

 true also for the 10-acre grove or the 1-acre truck patch. For the 

 irrigation of a grove the surface methods probably would prove 

 most satisfactory, and an irrigation equivalent to not less than 

 two inches of rain should be figured on. A truck patch should have 

 about the same amount for furrow irrigation, and about one-half 

 of this if spray methods are employed. Another important factor 

 to be considered in determining the necessary capacity of the plant 

 is the time the farmer desires to consume in watering the grove. If 

 he is willing to irrigate 24 hours a day he can get along on half the 

 amount of water needed per minute in a day half as long. But night 

 irrigation by surface methods seems to be unpopular in Florida and 

 it will be best to figure on a 12-hour irrigation day. The personal 

 element also enters into the number of days of irrigation required 

 to cover the grove, but it is doubtful if a plant can be considered 

 efficient if it will not furnish enough water to cover the grove in 

 10 days. This period is a good standard for use in Florida. 



If 2 inches of water is to be applied to a 100-acre grove in 10 days 

 of 12 hours each, the problem of figuring the gallons per minute is a 

 simple arithmetical one; and this is equally true whether the grove 

 contains 52 acres or 7 acres. There are 27,154 gallons in an acre- 

 inch. "Considering loss in transmitting and other losses while irri- 

 gating, it is better and easier to say that it requires 30,000 gallons of 

 water to cover 1 acre 1 inch deep, or 60,000 gallons 2 inches deep. 

 In the 100-acre grove it is necessary to apply 200 acre-inches, or 

 6,000,000 gallons of water. If this is done in 10 days, or 120 hours, 



„c,™ ■ , • t i -• 6,000,000 „ nn . 



or 7,200 minutes, a pump having a discharge or „ 9 nn — 3 or 833 gal- 

 lons per minute, will meet requirements. For any other acreage, 

 gallons divided by minutes will give the capacity of the pump per 

 minute. 



Two acre-inches of water would answer for the furrow-irrigated 

 patch if diversified truck crops which did not all need water at the 

 same time were grown, but as the truck crops require a more rapid 

 irrigation than the grove, owing to earlier injury from drought, it 

 is well to double this estimate where such crops are to be watered. 

 Irrigation by spray methods brings in other problems which can be 

 solved readily, although they are of a different nature from those 

 just discussed. For the spray plant it is advisable to figure on a 



