THE MANURING OF THE CANE 99 



casted by manure distributors and incorporated in the soil by harrows 

 in the operations previous to planting. 



The experiments with pen manure in the British West Indies point to 

 the conclusion that applications to plant canes followed by the use of readily 

 available nitrogen on ratoon crops give the best financial returns. 



With the general increase in the size of estates and consequent necessity 

 for mechanical traction, pen manure is losing its importance, and its place 

 is being taken by artificial fertilizers. The fertility of soils in districts 

 such as Barbados and Mauritius over many generations is, the writer 

 believes, to be largely attributed to the extensive and well-ordered use of 

 the pen manure manufactured on the estates. The modern tendency is 

 to grow crops with the aid of irrigation and of the more concentrated artificial 

 manures, and it largely becomes a question of the cost of the labour required 

 to make and to apply the pen manure compared with that required for the 

 purchase and application of the artificial manure. It is not yet known 

 what will be the final effect on the soil in several generations of the modern 

 practice. 



The Return of Plant Residues. Considered as a principle in agriculture, 

 everything produced from the soil, except that portion which forms the 

 commodity which is marketed, should be returned to the soil. Generations 

 of experience have established this principle in the older civilization, and to 

 its observance is to be attributed the long-continued productivity of the soils 

 of Europe and of Asia. To its neglect is to be assigned the continued march 

 westward of American farming. The very many analyses which have been 

 made of the cane afford means to construct a balance sheet of the demands 

 made by the cane on the soil., and of the distribution of the plant food re- 

 moved. The analyses quoted in Chapter II, however, show that from 

 -analysis to analysis very great difference results. Reviewing, however, 

 a great mass of data the following balance sheet can be presented, as giving 

 an average of the essential features, with the proviso attached that individual 

 analyses can be found showing very different results : 



AGRICULTURAL BALANCE SHEET OF A CANE CROP. 



. PER 1,000 TONS OF STALKS. 



Phosphoric 



Lime. Potash. acid. Nitrogen. 



Leaves, Tops, Roots 2000 75 noo 2500 



Stalks . . . 500 3000 1000 1000 



5 550 15 5 



Sugars . . 

 Molasses 

 Bagasse 

 Press cake 



250 2150 95 250 



50 300 100 100 



750 790 600 



In the construction of this balance sheet the manufacture of 96 test 

 sugar is assumed together with a high extraction at the mill. It is at once 

 apparent that the distribution of the elements brought to the factory with 

 the stalks will vary with the " extraction " and by the distribution of the 

 output between sugar and molasses. This in turn will be controlled by the 

 purity of the juice. In constructing the table, allowance is made for the 

 quantity of lime used in defecation. 



Inspection of the tabulated statement shows that the greater proportion 

 of the material removed from the soil by the crop is contained in the residue 



