96 DEPARTMENT OF AGRICULTURE GEORGIA. [382] 



calculate beforehand, with a moderate degree of certainty, 

 the increase that will result from the application of a spe- 

 cific amount of plant-food, in the proper combination, if 

 other circumstances are favorable. 



To illustrate : If the natural soil will produce 12 bushels 

 of oats per acre, with the necessary amount of straw as- 

 suming that the soil (as is usually the case) contains a suf- 

 cient supply of lime, soda, magnesia, sulphuric acid, and 

 chlorine it may be reasonably expected that the applica- 

 tion of 12 pounds of nitrogen, 4.72 pounds of potash, and 

 2.27 pounds of phosphoric acid, would produce 24 bush- 

 els, with the necessary straw, or 12 bushels more than the 

 natural soil ; but the results depend upon such a variety 

 of circumstances, that many experiments will be required 

 to establish the correctness of the assumption. 



Since all of the mineral food derived from the soil must 

 pass into the plant in solution in water, each element, to 

 be available to the plant, must be either soluble, or 

 promptly rendered so, by natural agencies, during the pe- 

 riod of active growth of the plant. 



The influence of climate must be considered in the treat- 

 ment of soils. This is too often neglected by farmers in 

 the South, whose agricultural literature is principally 

 adapted to more northern climates, where most of such 

 literature has originated. 



While the general principles of agricultural science are 

 the same everywhere, their application to practice varies ac- 

 cording to a multiplicity of circumstances, the influence of 

 which, each individual must decide for himself, according 

 to his surroundings. 



Soils in a warm climate are more rapidly exhausted 

 under tillage than those of cold climates, for the following 

 reasons : 



1. Vegetation has a longer period of growth in warm 

 climates, in which to extract plant-food from the soil., 



2. There is a less rapid and thorough decomposition of 



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