II VANILLA 35 
formerly subterranean roots bare and also taking away 
their nutriment. 
Then when the weather is hot and dry, the ground 
cracks under the blazing sun, breaking across any young 
roots which may be in the line of the crack, and the 
surface soil loses its moisture and the roots beneath, even 
if not broken, are dried up. 
In spite of these obvious objections, there are many 
planters who insist on having a perfectly bare, dried-up, 
sun-cracked soil for whatever plant they are cultivating, 
in fact, what is known as a clean estate. Plants, how- 
ever, are not accustomed to this condition, and it is 
quite an unnatural state for any form of tropical 
cultivation. 
Draining . — Whether draining is necessary or not 
on the estate depends entirely upon the position and lie 
of the land. Where hill slopes are used there will, of 
course, be no necessity for any drainage system. In 
low-lying ground where the soil is at all water-logged, 
the ground must be drained, but such soil is not good 
for vanilla, however it is treated, and should be avoided. 
Much of the injury caused by the fungus disease in 
Mauritius was attributed to bad or insufficient drainage. 
Manuring . — Where the soil is rich in humus of 
sufficient depth it is unnecessary to add anything in 
the way of manure, but the ground should be dug over 
and broken up before planting. If the soil is poor in 
humus, leaf-mould or decaying leaves may be spread on 
the ground, and burnt earth may be liberally used. 
As burnt earth is widely used in the tropics for 
many different crops, and will be mentioned again, I 
will here describe the method of making it. Low scrub, 
bushes, boughs of trees and other such vegetation are 
cut, and partly dried by being left in the sun. A 
quantity is laid on the ground and covered with soil, 
adding alternately more branches and more soil, until 
a good-sized pile is made. This is then ignited and 
allowed to smoulder for some days or even weeks, until 
the vegetable matter is charred. After being allowed 
