566 FIBRES 



If less efficient methods of cultivation are employed, 

 e.g., " wild cultivation," which will be described later on, 

 replanting is carried out on totally different lines. 



Harvesting, 



As to the time of ripening of the leaves no definite 

 statements can be made, since it depends upon various 

 circumstances. Differences are seen between cultures 

 derived from bulbils and those grown from suckers. 

 Furthermore, the growth of the plants, and therefore the 

 term of their harvest, is greatly influenced by the quality 

 of the soil. In fact, it will be well to mention especially 

 that the quality of the soil exerts a greater influence than 

 climatic conditions. For example, one may note that after 

 several months' drought the plants may do quite well and 

 produce particularly firm leaves, an observation which 

 recalls the intensive growth of our indigenous plants 

 after their winter's rest. 



The right time for cutting the leaves will be discussed 

 subsequently. At present it will suffice to mention a sign 

 of the ripeness of the leaves; in young leaves the tips are 

 purplish-brown and glossy, but when the leaf matures it 

 has a silver-grey hue. 



In German East Africa cultivation is at present carried 

 out chiefly in two ways. One is that of " methodical 

 cultivation," already dealt with, the other is that of 

 " wild cultivation." If the soil is not too rich and does 

 not contain too much humus it is considered typically 

 suitable for sisal culture in most tropical countries. 

 Under such " normal " conditions the first leaves can 

 usually be cut three years after planting. One may then 

 continue harvesting the leaves for about five to seven 

 years. In general, a sisal plant produces about 200 

 leaves suitable for fibre production during its entire life- 

 time. Normally, therefore, one whole period of sisal 

 cultivation lasts for about ten years. 



With regard to the influence of the soil on the ripening 

 of the leaves one should distinguish (i) very rich virgin 

 soils, (2) medium soils with a certain amount of nutritive 

 material and humus, and (3) poor soil, e.g., rocky or 

 chalky soil near the sea coast. The medium soils we 



