32 



DRY-LAND OLIVE CULTURE IN NORTHERN AFRICA. 



weight increase rapidly with the age of the tree. When 25 years 

 old, the average yield of oil per tree is about 6 gallons. Some 

 individual trees attain a production of over 50 gallons of fruit, 

 but such heavy bearers are said to constitute not more than 1 or 2 

 per cent of the Sfax orchards. 



After the trees have come into full bearing their yields are said 

 to remain stationary until they are 50 years old, when their pro- 

 ductiveness begins to decline. When 80 years old the yields are said 

 to diminish and become very irregular, dwindling to almost nothing 

 in trees a hundred 3 r ears old. If thoroughly pruned, cultivated 

 deeply enough to lay bare the roots, and well manured, however, old 

 trees can again be brought into bearing. 



The crop at Sfax from trees over 20 years old is said to be worth 

 on an average about $2, although sometimes attaining from $3 to $4 

 per tree. It must be remembered, however, that there are only seven 

 to ten trees to the acre. 



It is instructive to compare the yields given in Table IY with 

 those obtained in other olive-growing countries. Thus, in Provence, 

 in southern France, well cared for trees in full bearing are said to 

 produce an average of only 3.9 to 5.3 gallons of fruit, which, if 

 we take the percentage of oil to be about half what it is at Sfax, 

 would give about 0.6 gallon of oil. Hence, although in Provence 

 the trees are planted only 33 feet apart, which allows about 60 to the 

 acre when in squares and 70 when in quincunx, the yield of oil to the 

 acre from well-tended orchards would still fall short of that at Sfax. 



The olive is markedly periodic in its bearing and will not produce 

 two heavy crops in succession, no matter how favorable the climatic 

 conditions may be. At Sfax the rule is said to be that if a tree 

 yields heavily one season it will give a medium crop the second and 

 a light crop the third season following. Different trees yield heavily 

 in different years, so that every year some trees are giving their 

 maximum crop. 



In January, 1900, there were in operation at Sfax 28 oil mills 

 operated by steam power and 48 native mills operated by animal 

 power. There were 15 mills controlled by Europeans and equipped 

 with modern machinery. The total number of presses was 155, of 

 which 56 were run by steam and 99 by animal traction. 



RELATION OF RAINFALL TO YIELDS. 



It is interesting to compare the amount of rainfall with the char- 

 acter of the olive crop at Sfax during each of a series of years, such 

 a comparison being given in Table V and being shown also in 

 figure 10. 



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