V 



FIELD CULTURE 



159 



given time, and this is determined by the rate at which 

 the leaf primordia are developed around the growing 

 point of the trunk. Dissections of coco-nut trees show 

 from 17 to 23 or 25 distinct leaves which are not yet 

 visible without dissection. Microscopical study would 

 of course increase this number. 



Assuming that there are 24 such leaves, and that 

 the rate of appearance is 16 a year, the youngest of 

 these will require a year and a half before the tip can be 

 detected in the crown of the tree. After a leaf becomes 

 visible, it requires at least six months for the production 

 of flowers in the axil and still another nine months for 

 the production of the fruit. Under the conditions which 

 have been assumed, which are approximately those 

 occurring in nature, it will therefore be two years and 

 nine months before an improvement in the cultural 

 conditions can^ by increasing the rate at which the 

 new leaves are formed, increase the production of a 

 marketable crop. 



It follows most obviously that data as to the 

 effectiveness of the application of any fertilizer are in- 

 complete unless carried on for more than three years 

 after the application. The fertilizer has no direct effect 

 on the size of the nuts, or the tree's ability to mature all 

 which set, or even the rate at which new clusters of 

 nuts are produced. Its first visible effect may be upon 

 the growth of roots or of leaves, both directly and in- 

 directly. Chiefly through its effect upon growth, a 

 fertilizer is expected to increase the rate of formation 

 of organic material by the leaves. And it is only after 

 it begins to make itself felt by an increase in the 

 assimilative activity of the leaves that it can begin to 

 have any influence upon the production of a crop. 

 If the time necessary for this effect upon the general 

 vegetative activity of the tree be added to the two 

 years and nine months, — which is probably already below 

 the time in which the rate at which the new leaves are 

 laid down can begin to influence the production, — it is 

 obvious that rather more than three years must pass 



