CROPPING SYSTEMS, FERTILIZERS FOR CORN 223 



culture (Bui. 64), one hundred and sixty-eight experiments 

 conducted by experiment stations in this country on the 

 use of lime for corn show an average increase of 3.2 

 bushels an acre at a cost of $8.91 for the lime. While 

 lime is an essential plant-food, most soils are abundantly 

 supplied in so far as the requirements for growth are 

 concerned. A 50-bushel corn crop requires approxi- 

 mately 12 pounds of lime. When lime is required it is 

 usually as a soil amendment rather than a direct food for 

 the crop. 



The soil conditions which would respond profitably 

 to an application of lime in producing corn may be divided 

 into three clases: (1) Low-lying soils that have remained 

 wet for a number of years and, following drainage, remain* 

 sour; (2) upland sandy soils to which large quantities of 

 vegetable matter have been added, the decomposition of 

 which would sour the soil; (3) heavy clay soils in humid 

 regions, where the aeration is poor and consequently the 

 plant-food is in an unavailable form. 



271. Fertilizers for corn. The fertilizer practice 

 in the production of corn in the cotton-belt has been much 

 abused. Two mistakes are most often noticed. (1) The 

 application of complete ready mixed fertilizers regardless 

 of the needs of the particular soil in question; (2) depend- 

 ing upon fertilizers to offset the ill-effects of the one-crop 

 system, poor tillage, and lack of drainage. The most 

 profitable returns from fertilizers are possible only when 

 they are employed to supplement the other essential fea- 

 tures of good soil management. 



272. Plant-food removed by corn. The require- 

 ments of corn for the three plant-food constituents that 

 are recognized as having money values in commercial 

 fertilizers are indicated on page 224: 



