

[355] SCIENTIFIC MANUAL. 69 



are supposed to be necessary to the production of the 

 maximum crop. These constituents are varied in kind, 

 quantity and ratio, to suit the requirements of different 

 plants, and are also modified by circumstances of soil, tem- 

 perature and supply of moisture. 



To illustrate : the tobacco planter requires a fertilizer 

 richer in potash than in phosphoric acid, with a liberal 

 percentage of ammonia, lime, magnesia, chlorine, and soda, 

 unless these ingredients already exist in abundance in the 

 soil. The cotton planter requires more phosphoric acid 

 than potash, which together, with ammonia, are the princi- 

 paHingredients of the fertilizers usually applied to cotton. 



Plant fertilization is generally practiced in Georgia, 

 and in all other States where land is cheap, and large sur- 

 faces cultivated. It is a temporary resort for immediate 

 results ; and though securing profitable crops, seldom per- 

 manently improves the quality of the soil, unless combined 

 with judicious and systematic rotation of crops, involving 

 b,)th protection from summer suns, and a return to the soil 

 of a large part of the vegetable matter produced. It is the 

 most economical method of fertilization, where immediate 

 returns are sought, since the plant-food is applied in such 

 mechanical and chemical condition, and in such proximity 

 to the roots of the plant, as to be promptly available, and 

 thus returning principal and interest in the first crop, 

 under favorable meteorological conditions both as to tem- 

 perature and moisture. In plant fertilization the manure 

 is applied in the hill or drill, the method usually employed 

 in Georgia, so that the first roots put forth reach the ma- 

 nure, and thus give the plant an early, vigorous start. 

 This effect has been particularly marked in North Georgia, 

 in pushing forward the cotton plant and hastening its ma- 

 turity, in advance of early frosts. Indeed, this system of 

 plant fertilization has extended the area of profitable cot- 

 ton culture about fifty miles north of the original limit, 

 since its effect is to practically lengthen the season of 



