THE MANURING OF THE CANE 87 



with the cane this feature should be of importance when the intimate con- 

 nection between the leaves and stem is considered. 



It is often asked if one or two applications of the same amount of nitrogen 

 are the more beneficial. Watts' experiments in the Leeward Islands 14 point 

 to the one-application system being the better, and he reasons on the following 

 lines : 



" These results lead us to make the suggestion that manures applied to sugar 

 canes will probably be found to be more efficient, both physiologically and pecuni- 

 arily, if given in quick-acting forms at a very early stage of the cane's growth, and 

 we are led to speculate if this may not be accounted for, on botanical grounds, by 

 the structure and manner of growth of the cane. We have perhaps been too prone, 

 when thinking of manuring crops, to have in our mind dicotyledenous-branching 

 trees, with many growing points, instead of the sugar cane, with its one growing 

 point, or ' top ' to each stem. The cane having lost its habit of seeding may be 

 regarded as a growing top and a stem. When the former has arrived at its full 

 development it may be taken roughly to be a fixed quantity ; old leaves fall away 

 and are replaced by new ones, so that the top remains fairly constant. The stem 

 constantly receives additions, and gradually ripens to form a dormant sugar house 

 chiefly filled with sugar, doubtless originally destined to provide for the growth 

 of flowers and the production of the seed, but now developed to a greater extent 

 than the feebly fertile flowers demand. 



The elements of plant food, including nitrogen, potash and phosphate, are 

 found in greater abundance in the ' top ' and leaves than in the stem ; hence it 

 is reasonable to suppose that in the early development of the cane plant, with its 

 system of top and stem, greater demand is made upon the plant food supply of the 

 soil in order to build up this top rich in plant food than occurs later on when 

 the top, a comparatively fixed quantity, has been developed, and additions are being 

 made to the stem, which additions demand relatively large amounts of carbo- 

 hydrates, with comparatively small amounts of nitrogen, potash and phosphates. 

 Transference of plant material from point to point takes place freely, and it is 

 reasonable to suppose that the cells of the stem, as they pass into the dormant 

 condition, may pass on some of their nitrogen, potash and phosphate to be used in 

 building up newer structures. We are aware of this transference of plant food in 

 the case of the leaves, where the faded and falling cane leaves contain much less 

 plant food than the actively growing ones. 



In order to have fresh information on this point analyses have been made 

 of fresh cane leaves, and of dry cane leaves just as they were about to fall from the 

 plant but not actually fallen. 



The results are as follows, and show in a striking manner the nature of the 

 transference of plant food material from the leaf back to the stem as it ripens 

 and as its lower portion becomes dormant : 



Nitrogen .. 



101-41 . . ioi 13 



0-777 on dried 0-36 on dried 

 leaves. trash. 



