THE MANURING OF THE CANE. 



7. The demand of the sugar cane for lime as a plant food is low, and if 

 a soil gives up more than '006 per cent, to the 1 per cent, citric acid solution, 

 it probably will yield sufficient for plant food for ordinary crops of sugar cane. 



Barbados. Harrison and Bovell 4 in a series of experiments, carried out 

 between 1885 and 1889 at Dodd's Reformatory in Barbados, came to the 

 general conclusions detailed below : 



1. The addition of readily available nitrogen to mineral manures produces 

 a large increase in the weights of cane grown, but excessive dressing (over 3 

 cwts. sulphate of ammonia per acre) may cause a marked decrease in the rich- 

 ness and purity of the juice. 



2. Under certain climatic conditions, manuring with nitrogen in form of 

 slowly decomposing organic matter may, if applied before or soon after the 

 planting of the canes, produce excellent results. Applications of such slow 

 acting manures in June or July at the period of the sugar cane's most active 

 growth are unadvisable, and may result in considerable loss. 



3. Upon the soil, and under the climatic conditions existing at Dodds' 

 during the years 1885 to 1889, both inclusive, nitrate of soda was markedly 

 inferior to sulphate of ammonia as a source of nitrogen for sugar cane. 



4. The profitable employment of purely nitrogenous manures depends 

 largely upon the state of the soil. If the soil is in good heart, such applications 

 may realize heavy returns, if poor such manurings will result in heavy loss. 



5. For the maximum return of sugar cane by manuring, phosphates must 

 be present in the manures used. 



6. If such phosphates are applied in the form of superphosphate of lime, 

 great care must be exercised in their use and application, as whilst light dress- 

 ings of superphosphate capable of supplying 75lbs. or SOlbs. per acre of "soluble 

 phosphate" (equivalent to from 16 to 18 per cent, of ''soluble phosphates" in 

 commerical sugar cane manures when applied at the rate of one ton to five acres), 

 may produce large increases in the weights of canes, &c. , heavier dressings do 

 not produce corresponding increases, and excessive ones may even reduce the 

 produce below that obtained when manuring with nitrogen and potash only. 



7. The use of insoluble phosphates such as precipitated and mineral 

 phosphates is not advisable during the period of the cane's active growth, but 

 may produce excellent results when applied to the soil at an early period, in a 

 very fine state of sub-division in large quantities, and uniformly mixed with it. 

 To obtain, however, equally profitable results with these phosphates, as with 

 moderate applications of superphosphates, it is absolutely necessary that they be 

 purchasable at far lower prices than they can be at present obtained in 

 Barbados. 



8. The addition of potash to manurings of phosphates and nitrogen pro- 

 duces in all soils at all deficient in available potash large increases in the yield 

 of cane and of available sugar in the juice per acre. 



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