20 DRY-LAND OLIVE CULTURE IN NORTHERN AFRICA. 



Opinions differ as to whether the high stearin content of the Sfax 

 olive oils is a peculiarity of the Chemlaly variety or is due to the 

 character of the soils of Sfax. That it is not attributable to the 

 climate seems certain, for oils made from olives grown in still hotter 

 and drier parts of Tunis are said not to congeal more readily than 

 do those from the northern part of the country. M. Bertainchand, 

 the chief chemist of the Tunis government, holds the character of 

 the soil to be responsible, the soils in which olives are grown in 

 northern Tunis being generally heavier than those of Sfax. It should 

 be noted, however, that oils produced in the oases on the northern 

 edge of the Sahara, where the soils are sandier than at Sfax, resemble 

 the oils of northern Tunis rather than those of Sfax in their per- 

 centages of fluid and fixed acids. Perhaps the low water content 

 of the soil contributes to this peculiarity in the composition of Sfax 

 oils, northern Tunis having a much higher rainfall and the oases 

 being abundantly irrigated. The latest authority who has investi- 

 gated this subject holds, however, that the percentage of stearin is 

 essentially a characteristic of the variety rather than a direct result 

 of the physical conditions.* 



Whether the large yields of fruit obtained at Sfax from the 

 Chemlaly olive are an inherent characteristic of the variety or are 

 due to the climate or the soil or the superior cultural methods used 

 seems not to be known. All authorities agree, however, that 

 this variety is exceptionally well adapted to growing without irri- 

 gation in a hot, dry climate. It has been suggested by Dr. L. Trabut, 

 government botanist of Algeria, that the Chemlaly will probably 

 be useful as a drought-resistant stock upon which to graft larger 

 fruited varieties. It is, in fact, thus employed to some extent at 

 Sfax, but its value for this purpose will probably be limited, since 

 olives that are large enough to be commercially valuable for pick- 

 ling can in all likelihood be produced only where abundant water 

 is available. 



PROPAGATION. 



The Chemlaly olive is never grafted at Sfax but is grown on its 

 own roots. It is always propagated by means of large truncheons — 

 pieces of wood taken from the base of the trunk or of the largest 

 roots — a method that seems to be peculiar to Tunis. 6 These cuttings 



a See Marcille, in Bui. Dir. Agric. et Com., Tunis, 1906, p. 516. 



6 Dr. L. Trabut, the government botanist of Algeria, states that it is not 

 practiced in Algeria. Prof. S. C. Mason, arboriculturist of the Bureau of Plant 

 Industry, reports that the Cottonwood (Populus deltoides) is sometimes propa- 

 gated in western Kansas by means of " snags," or truncheons, pieces of wood 

 with several buds obtained by cutting up the branches of this tree. They are 

 of the thickness of a piece of stove wood and 1 or 2 feet long. They are some- 

 times set in deep furrows and the soil is then firmed in around them. 

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