SUGAR-CANE 495 



ficient in plant-food,' than the soils of the sugar-belt of 

 Louisiana. Therefore', on such upland the yield of cane 

 per acre is usually lighter. However, there is partial com- 

 pensation in the fact that cane grown on the pine lands 

 is ordinarily richer in total sugars than cane grown on 

 the alluvial lands in Louisiana, 



477. Fertilizers. — Under the system generally prac- 

 ticed in Louisiana, the tops and leaves are annually burned 

 on the field, thus returning to the soil a part of the phos- 

 phoric acid and potash, but robbing the soil of practically 

 all of the nitrogen contained in the above-ground part 

 of the plant. Therefore, the principal fertilizer constituent 

 needed is nitrogen. Experiments at the Louisiana Sugar 

 Station have indicated that as much as 48 pounds of nitro- 

 gen per acre can be applied with profit in the form of com- 

 mercial fertilizers. This amount is contained in about 340 

 pounds of nitrate of soda or in larger amounts of cotton- 

 seed meal, dried blood, or tankage. An application of 36 

 pounds of phosphoric acid per acre was found to be suffi- 

 cient for Louisiana soils. This amount is contained in 

 about 250 pounds of acid phosphate. Louisiana experi- 

 ments showed that cane grown on the soils of the sugar- 

 belt needed but Httle, if any, potash. No fertilizer was 

 found to influence notably the percentage of sugar in the 

 juice, when the fertilizer was used in moderation on rich 

 alluvial soils. 



Part of the commercial fertilizer is advantageously ap- 

 plied before the planting of the cane, and a part may be 

 reserved for application soon after growth begins. If 

 nitrogenous fertilizer is applied too late in the summer, it 

 delays the ripening of the cane, and hence reduces the yield 



