6o ALGERIA 



been proved more advantageous to concentrate the yield peri- 

 odically; and 3 years, a multiple of either 9 or 12, the usual 

 minimum and maximum period for the maturity of any one 

 bark crop, is the interval between harvests. 



Cultural Rules. — It is considered more profitable not to 

 peel trees when too young; in the past there has been a tend- 

 ency to commence with trees 50 m. to 60 m. (20 to 24 inches) 

 in circumference (30 to 40 years old), whereas it is essential on 

 average soil to wait until a tree reaches 70 m. (27 inches) or 

 even 80 m. (31 inches). Under favorable conditions 5 or 6 

 collections may be expected, since trees continue to bear until 

 80 to 100 years of age. If collection is allowed to begin when 

 a tree is too young the growth is retarded, the tree yields a 

 furrowed cork of such poor quaHty as hardly to pay for the 

 cost of collecting, and often results in the death of the tree. 



When a tree has once attained merchantable size it is marked 

 for peeling. The bark which results from this first operation 

 has Httle or no commercial value (Hege male). Dating from 

 the time this rough primary back crop is removed, it takes on 

 an average a minimum of i year and a maximum of 12 years 

 for the merchantable cork to reach 0.025 m. (0.975 inch) 

 (0.028 (i inch) with epidermis) in thickness — which is the 

 merchantable size. This would indicate an average increase of 

 about 0.0029 (o.ii inch) per year, but in reality the growth 

 in thickness diminishes as the age of maturity approaches. 



At the end of 9 years the cork on one-half the trees should 

 reach merchantable size, and the rest by the end of the 12-year 

 period, with a mathematical average maturity of 11 years, 

 although it must be admitted that some trees are ripe after 7 

 or 8 years where the growth is vigorous. As a rule, however, 

 the more rapid the growth the lower the quaHty of the cork. 



A simple gauge (Uke a shoemaker's awl) is used to measure 

 the thickness of the cork when marking trees to be cropped. 

 The incision is commenced (usually sawed just to the cambium) 

 at the root collar and vigorous trees can be barked to a height 

 equal to 2.5 times the circumference; in other words, a tree 

 70 m. (27 inches) in circumference would be peeled to a height 



