SOILS AND FERTILIZERS 401 



added are already in abundance in the soil, or so little of the fer- 

 tilizer is used as to preclude any profit. 



The lacking element can not be fully determined, except by 

 direct experiments by the farmer himself. That is, no general prin- 

 ciple can be depended on as an absolute guide. He should learn 

 whether his soil is deficient in any of the elements, and, if so, which 

 one should be applied to the different crops in his rotation. A care* 

 ful study along this line, too, will show whether it is fertilization 

 that is required to meet seeming deficiencies, for it frequently hap- 

 pens that the needs of the soil are not so much for added plant food 

 as for better management of the soil in other respects. 



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-producing soils 

 of Louisiana and Mississippi, and the cotton soils of Georgia and 

 Texas, the addition of potash has been of less importance in the past 

 than the other elements, and it frequently does not need to be in- 

 cluded in the fertilizer, while phosphoric acid is always needed. 



The results of field experiments on this plan in New Jersey, on 

 reasonably good, loamy soils, indicate that phosphoric acid and 

 potash are of much more importance in fertilizers for corn than 

 nitrogen, whereas upon sandy soils nitrogen and potash are of rela- 

 tively more importance than phosphoric acid; that is, even where 

 extensive practice is used there are conditions where one or more of 

 the elements are not required in order to secure maximum crops, 

 which eliminates the necessity for an immediate outlay for those 

 constituents that are not lacking. Where experiments of this sort 

 have not been carried out and the specific needs determined, it 

 becomes necessary to assume that all of the constituents are required, 

 and to apply the amounts and proportions of those which the gen- 

 eral considerations of the soil, season, climate and crop would seem 

 to demand. 



The methods of fertilization here suggested, though in many 

 instances apparently positive, are not to be interpreted as absolute 

 rules, but rather used as guides, based upon the best information 

 that it has been possible to obtain, both as a result of scientific in- 

 quiry and of practical experience. 



The main point in this whole matter of fertilization is to under- 

 stand that a fertilizer is a fertilizer because of the kind and form of 

 i plant food contained in it; and that its best a,ction, other things 

 being equal, is accomplished when the soil possesses good physical 

 \ qualities, when the management is also good, and when systematic 

 methods are planned and adopted. Hit or miss fertilization, even 

 for these crops, may pay, and doubtless on the average does pay as 

 well as some other things that farmers do, but does not pay as well 

 as it might if better methods were used. 



