214 Fertilizers 



frequently pay well for the application of the material, 

 even though the margin of money profit is small. In 

 crops of this sort therefore, and especially when grown 

 on the "extensive" plan, an important point to be 

 determined is whether the land is deficient in all of 

 the constituents for grain and hay growing, or whether 

 only one or two are lacking, in order that in the appli- 

 cations made, only those constituents are supplied that 

 are necessary, and adding to an excess already present 

 is thus avoided, with a consequent saving in the cost 

 of the fertilizer. 



EXPERIMENTS TO DETERMINE THE LACKING ELEMENT 



The lacking element cannot be fully determined, except 

 by direct experiments by the farmer himself. That is, 

 no general principle 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 ones should be 

 applied to the different crops in his rotation. A careful 

 study along this line, too, will show whether it is fertiliza- 

 tion that is required to meet seeming deficiencies, for it fre- 

 quently happens that the needs of the soil are not so much 

 for added plant-food as for better management of the 

 soil in other respects, in order that natural supplies may 

 be made more available. 



It may seem, at first glance, that experimenting should 

 be left to the experiment stations, and that farmers 

 should be advised by them of the needs of their soils in 

 respect to plant-food. This is partly true, but the proper 

 function of experiment stations is to establish principles, 

 the application of which must be left, in large part at 

 least, to the intelligence of those who are to utilize them. 



