496 SOUTHERN FIELD CROPS 



of sugar, or injures the quality of sirup. Phosphates tend 

 to hasten the ripening of cane, as also of other plants. 



478. Source of nitrogen. The demands for a large 

 amount of nitrogen are met by the planters of Louisiana by 

 plowing under, every third or fourth year, a luxuriant 

 growth of cowpeas, usually grown in the corn in rotation 

 with sugar-cane. In the pine-belt east of the Mississippi 

 River, nitrogen should be supplied by plowing under, 

 the year before planting cane, a luxuriant growth of vel- 

 vet beans or of the Iron variety of cowpeas. 



479. Fertilizer experiments with cane in the pine-belt. 

 An extensive series of fertilizer experiments was conducted 

 for two years by the United States Department of Agri- 

 culture on sandy pine land in the southern part of Georgia. 



This field had been in cultivation for a number of years. 

 When cane was not preceded by a soil-improving crop, the 

 results were as follows : 



(1) The fertilizer formula that can be recommended as the 

 result of these tests consists of 



600 pounds high-grade acid phosphate, 

 100 pounds cotton-seed meal, 

 300 pounds nitrate of soda, 

 100 pounds sulfate or muriate of potash, 

 1100 pounds, total per acre. 



Such a fertilizer would contain about 86 pounds of available 

 phosphoric acid, 50 pounds of nitrogen, and 50 pounds of potash, 

 and would analyze approximately as follows : 



8.0 per cent of available phosphoric acid, 

 4.5 per cent of nitrogen, 

 4.5 per cent of potash. 



In these tests 1200 pounds, and even 2000 pounds, of a com- 

 plete fertilizer was more profitable than 800 pounds on sandy 



