FOOD REQUIREMENTS OF CROPS 263 



matter or humic acid where wheat would be destroyed. 

 In a rotation, oats usually occupy a position less fa- 

 vored by manures ; they are, however, greatly benefited 

 by fertilizers, particularly those of a nitrogenous 

 nature. The oat crop responds liberally to manuring. 

 Light dressings of farm manure can be applied directly 

 to oat land when well worked into the soil before 

 seeding. 



313. Corn. Experiments with corn indicate that 

 under ordinary conditions it requires most help in 

 obtaining phosphoric acid. Corn removes a large 

 amount of gross fertility, and if its production is long- 

 continued without the use of manures it impoverishes 

 the soil. Its habits of growth, however, are such that it 

 generally leaves an average prairie soil in better me- 

 chanical condition for succeeding crops. Corn is not 

 injured as are many grain crops by heavy applications 

 of stable manure, and does not, like flax, produce waste 

 products which are destructive to itself. The conditions 

 are better for wheat culture after one or two corn crops 

 have been removed from rich, newly broken prairie soil. 

 The food requirements of corn are satisfied by applica- 

 tions of stable manure, occasionally reenforced with 

 a little nitrogen and phosphoric acid, and in the case of 

 some soil potash. After clover, corn gives excellent 

 returns, and when corn is the chief market crop it 

 should be favored by having the best position in the 

 rotation. 



