- 6 - 



Equipment - To irrigate efficiently, the grower should have 

 sufficient pipe to cover 2 to 3 acres, depending on the dis- 

 tance from water supply, and a pump to deliver a minimum of 

 one-half inch per hour to this acreage. Less pipe or less 

 power greatly increases the cost per acre inch and reduces 

 the acreage that can be covered. 



Water supply - If irrigation is to be undertaken seriously, 

 there should be enough water to apply 12 inches to 30 acres, 

 or more, in even the driest years . This requires 7.5 million 

 gallons. 



Varieties - The increase in yieJ.d that can be expected is not 

 enough to support this expensive operation. Sales value of the 

 fruit must also be increased. This requires more of a price 

 differential between sizes than $2.00 appJes will provide. 



Assuming that all of the above conditions are satisfactorily 

 met, the response to supplemental irrigation will then be dependent 

 upon rainfall. That the practice might be highly profitable in very 

 dry years like 1962 is generally conceded. The practical question 

 that arises is, what happens to this profit when it is spread over 

 the intervening years when irrigation is unnecessary or unprofitable? 



In computing the cost of irrigation, interest and depreciation 

 were charged on the basis of the average number of hours the equip- 

 ment might be operated per year. Using the number of days during 

 the growing season that soil moisture was below the critical level, 

 and assuming that an alert grower would want to irrigate almost every 

 day that such conditions prevailed, it appears that the equipment 

 might be used more than 600 hours in years like 1957 and 1962, or it 

 might not be needed at all, as was the case in 1956, 1959, and 1960. 

 But the annual average for the 9 years 1955 - 1963 was approximately 

 200 hours. 



The response of Delicious apples to irrigation in 1962 is pre- 

 sented in Table 1. 



Table 1. - The Effect of Irrigation on Size and Yield of 

 Delicious Apples - 1962 



Fruit size - percent of total 



Less than Yield - field 



Treatment 2h in. 2% - 3 in. 3 in. and up boxes per tree 



Unirrigated 33.4 66.6 16.1 



Irrigated 17.8 76.9 5^^3 18.3 



The response to irrigation obtained with Delicious in 1962 

 showed a net return per acre of $162. The added income was derived 

 from two sources; more bushels of apples and larger-sized apples. 

 After allowing for utilities and wastage, the volume of apples har- 

 vested and sold from the irrigated orchard increased 14- percent 

 compared with the unirrigated block. Irrigation resulted in 40 per- 



