THE MANURING OF THE CANE. 



The experiments made by Watts, described above, had already been 

 conceived as long ago as 1877 by Rouf in Martinique; his experiments and 

 conclusions, than which I have come across none others so complete, are quoted 

 in full from Delteil's Canne d Sucre. Rouf harvested, weighed and analysed 

 month by month a crop of cane planted in March of 1877. His results, which 

 I have translated into Ibs. per acre, are given in the annexed table ; they give 

 the weight of the crop and of the various bodies contained therein : on these 

 results he thus expresses himself : 



1. The absorption of minerals commences as soon as the development of 

 the plant allows, but evidently it is much more active if the plant finds the 

 necessary fertilizing principles at its disposal, and above all if the climatic 

 conditions are favourable. 



2. The progress is moderated from the sixth to the ninth month ; then the 

 march of the elements rises to the tenth and eleventh month, the time of the 

 maximum absorption. At this period the total weight of stalks and leaves is a 

 maximum ; the cane has absorbed all the minerals and nitrogen, and the weight 

 of dry matter also is the maximum. By the tenth month the cane has absorbed 

 a maximum of the following elements : phosphoric and sulphuric acids, potash, 

 soda and silica. At the eleventh month the elements which lagged behind are 

 absorbed up to the maximum ; these are lime, magnesia and nitrogen, and the 

 elements which first reached a maximum have begun to be eliminated. In the 

 twelfth month, the elimination of the last three elements begins and continues 

 for all until the cane is ripe. 



3. The cane should be manured early so as to place at its disposal 

 necessary food, and to accelerate the elaboration of sugar. 



4. The elimination of the excess of potash, chlorides and soda from the 

 stalk and their transport to the top and leaves are ended when the cane is ripe. 

 In the top of the cane are accumulated alkaline chlorides, glucose, albumenoid 

 and pectic bodies. 



The return of plant food to the soil by the plant as it ripens indicates the 

 agricultural economy of harvesting the crop at its period of maximum ripeness 

 as less plant food is then removed ; Rouf's analyses bring out this point very 

 clearly. 



Method of Application of Manures. On general principles 

 the proper form of application of the various artificial manures varies. 



Nitrate of soda and also nitrate of lime, being readily soluble and not 

 being fixed by the soil (i.e., rendered insoluble), are applied as top dressings. 



Ammonia salts are also readily diifusible, and are applied as top dressings. 



Organic forms of nitrogen requiring the action of soil organisms must be- 

 buried in the top two or three inches of the soil. 



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