72 FUNDAMENTALS OF AGRICULTURE. 



EXERCISE. i. How much filler would it be necessary to add to 

 a fertilizer made up of cotton-seed meal, kainit and acid phosphate, 

 of the following composition 8 per cent, available phosphoric acid, 

 1.65 per cent, nitrogen and 2 per cent, potash provided the acid 

 phosphate contains 14.5 per cent, of available phosphoric acid? 2. In 

 the above mixture how much available phosphoric acid and potash 

 does the cotton-seed meal furnish? 3. If kainit sells for $10 a ton 

 and muriate of potash for $40 a ton, which is the cheaper source of 

 potash? Which is the more economical to buy, cotton-seed meal 

 containing 6.5 per cent nitrogen at $25 a ton, or cotton-seed meal 

 carrying 6 per cent, nitrogen at $24 a ton? 



SECTION XV. APPLICATION OF FERTILIZERS. 



Why Fertilizers are Added. In the harvesting of 

 crops a great deal of plant food namely, nitrogen, 

 phosphoric acid and potash is taken away from the 

 soil. In order to furnish the new crops with these 

 necessary ingredients, fertilizers are applied which 

 contain them. 



Amounts of Fertilizer per Acre. The amount of 

 fertilizer used per acre varies a great deal. The con- 

 dition of the soil and the nature of the crop regulate 

 to a certain extent the amount of fertilizer to use. As 

 a general rule the truck crops (lettuce, radish, cab- 

 bage, tomato, etc.) receive a great deal more fertilizer 

 than the general crops. Sometimes 1,000 Ibs. of fer- 

 tilizer are applied per acre for truck crops. The 

 quantities of fertilizer applied for cotton, corn, to- 

 bacco and other general crops are 200-600 Ibs. per 

 acre. 



Kinds of Fertilizers for the Crop. Some crops re- 

 quire different fertilizer ingredients from others. To- 

 bacco requires more potash than phosphoric acid. 

 Leguminous crops, such as cowpeas, alfalfa, soya bean, 

 etc., take nitrogen from the air and so it is unnecessary 

 to apply fertilizers containing nitrogen for these crops. 

 Wheat requires more nitrogen than any other ingredi- 

 ent for its production. 



Kinds of Fertilizers for the Soil. Soils are variable 

 in composition. Some soils contain enough potash for 



