218 Fertilizers 



desirable line of experimentation, and can be carried out 

 by individual farmers. It is useful not only in showing 

 the deficiencies of the soil for the various crops, but is 

 educative in its character, as it familiarizes the farmer with 

 the materials that are used in making fertilizers, and 

 encourages exact methods of work. Since, as already 

 stated, the need very frequently is not so much for added 

 fertility as it is for better preparation and cultivation of 

 the soil, or for amendments such as lime, it would be a 

 desirable practice to include in the number of plots here 

 indicated one or two in which the cultivation of the soil 

 was made more perfect, in order to determine whether 

 the need is for more fertility elements or whether it is for 

 better tillage, the effect of which is to render more of the 

 soil constituents available to the plant. One or two to 

 which lime is added may be advisable, in order to deter- 

 mine whether this substance is needed either to correct 

 acidity or to make available otherwise unusable com- 

 pounds. This method, while particularly desirable where 

 "extensive" methods of practice prevail, is of less im- 

 portance where the aim is to grow maximum crops, in 

 which case both the crop and its rotation are to be con- 

 sidered, and the needs of the plant rather than the de- 

 ficiencies of the soil require first attention. 



The results of experiments which have been conducted 

 with great care in a number of states show that where 

 "extensive" methods are practiced certain elements 

 need not be added in the fertilizers ; that is, that the soil 

 contains such an abundance of them that the plant is 

 able to obtain a full supply, at least, for a long time. For 

 example, it has been shown that on the chief sugar-pro- 

 ducing soils of Louisiana and Mississippi, and the cotton 

 soils of Georgia and Texas, the addition of potash has been 



