COMMERCIAL FERTILIZERS 69 



The amount of fertilizer which may be profitably used varies widely 

 with the season, nature of soil and other circumstances. On an average 

 the maximum amounts indicated for Georgia are nitrogen 20 pounds, 

 potash 20 pounds, phosphoric acid 70 pounds; those for South Carolina, 

 nitrogen 20 pounds, potash 15 pounds, phosphoric acid 50 pounds. 



Miscellaneous Fertilizer Facts. Wheat, to which a moderate 

 amount of manure has been applied, will not need additional nitrogen. 

 In most cases the manure can be profitably supplemented with phos- 

 phoric acid, and on some soils a small amount of potash may be included. 

 When the wheat field is seeded to clover and grass which is to be left 

 down for hay, the phosphoric acid and potash in the fertilizer should be 

 increased somewhat. 



Oats as a rule receive no commercial fertilizer. On soils low in fertil- 

 ity small applications of readily soluble nitrogen and phosphoric acid 

 applied at seeding time are advisable. Winter oats, grown mostly in the 

 South, are generally fertilized with light applications of phosphorus and 

 potash when seeded in the fall, and are top dressed with nitrate of soda 

 in the spring. 



For tobacco, barnyard manure occupies a leading position as a fer- 

 tilizer, both because of its cheapness and effectiveness. When manure 

 is not available in sufficient quantities commercial fertilizers are frequently 

 resorted to. In fact, the manure is often supplemented with commercial 

 fertilizers. This crop generally requires a complete fertilizer. Cotton- 

 seed meal is frequently used as a source of nitrogen for tobacco. How- 

 ever, manure is not used for bright tobacco and only very small amounts 

 of cottonseed meal are used. 



When nitrogen is required by a crop having a long growing season 

 it is generally advisable to combine it in two forms, one readily available 

 as nitrate of soda or sulphate of ammonia, the other in an organic form, 

 as dried blood or cottonseed meal. Where nitrate of soda is depended 

 upon entirely, two or more applications may be given during the growing 

 season. This is applicable to open, leachy soils, but is not essential on 

 heavy soils. 



Effect of Fertilizers on Proportion of Straw to Grain. The pro- 

 portion of straw to grain is influenced by season, soil and character of 

 fertilizer. At the Pennsylvania Experiment Station, in a test extending 

 through many years, it was found that for twenty-four different fertilizers 

 applied there were produced 52 pounds of stover for each 70 pounds of 

 ear corn. The average proportion for seven complete fertilizers was 55.4 

 pounds stover to 70 pounds corn. Barnyard manure gave 47.6 pounds 

 stover to 70 pounds corn, while a complete fertilizer containing dried 

 blood gave 58 pounds stover to 70 pounds corn. In case of oats, the 

 largest relative yield of straw was from barnyard manure. The average 

 for twenty-four different fertilizers was 45 pounds straw per bushel of 

 oats. The average for seven complete fertilizers was 42 pounds straw 



