CHAPTER III 1 



ORCHARD HEATING 



Late spring frosts cause immense losses of fruit in many sec- 

 tions of the country and help to discourage growers until many 

 of them neglect, destroy, or dispose of their orchards. 



Test by individuals and experiment stations that have tried 

 out heat as a means of frost protection has demonstrated the 

 following facts : 



i. That the temperature in an 

 orchard can be raised several de- 

 grees in time of frost. 



2. That orchard heating as a 

 method of insurance against frost 

 is practical in many sections dur- 

 ing most seasons. 



The type of heater to use. The 

 type of heater to be used must 

 be determined by each grower for 

 himself. In a general way it may 

 be said that the larger heaters will 

 give best satisfaction, as they fur- 

 nish a reservoir for the storing of oil for longer periods of firing. 

 It is almost impossible, and at least impracticable, to try to 

 refill the pots during the night. If the refilling equipment is 

 not working well, great loss is apt to result. A gallon of oil 

 will burn only about four hours, and as frost periods are apt to be 

 much longer than this, greater capacity is needed. Even though 

 some heaters may burn a gallon of oil for a longer period than 

 four hours, there must be a loss of heat, as it requires a certain 

 amount of burning oil to raise the temperature a given amount. If 

 a larger number of the smaller heaters are provided, so that a part can 

 be fired in the early part of the night and the remainder at successive 



1 After Iowa State College bulletins. 



27 



Fig. 5. Three different types of or- 

 chard heaters. (Iowa Agricultural 

 Experiment Station) 



