No. 4.] CO.MMKRCIAL FKRTJLIZERS. 139 



of stem and leaf. I have found in a luimb'er of experiments, 

 not only in Amlicrst but also over the State, that abundant 

 potash means a better ear of ensilage corn ; potash increases 

 not only tlie grain and the stalk, but it increases the stalk 

 and leaf relatively more than it increases the corn. I would 

 emphasize, I believe, adajMing the fertilizer to the crop a 

 little more strongly than Dr. Voorhees has done; for ex- 

 ]XM'i mental woi'k of the past twenty years has inii)ressed upon 

 my mind more and more strongly the fact that, in the case 

 of each of our important products, there seems to be one of 

 the three important elements which will increase that crop 

 to a nuich greater extent than the others. So that I am in- 

 clined somewhat to emphasize in my advice to farmers, most 

 of whom are using manure as well as fertilizers, keep in 

 niiiul the dominant element for your crop, and make sure 

 that the fertilizer which you use in general farming in con- 

 junction with manures shall be strong in the dominant ele- 

 ment feu- the particular crop which you want to grow. 



(^UESTiois". IIow about using phosphate rock in connec- 

 tion with manure ? 



Dr. VooKiiEES. I should use these insoluble phosphates 

 on soils rich in vegetable matter, or with manures, to get 

 results on soils not naturally I'ieh. You apply them on soils 

 where there is little activity and the chances are the acids 

 will not attack them very strongly. Apply them on manures, 

 and the natural tendency of manure is to decay ; and as the 

 decay i)roceeds, acids are formed and the insoluble com- 

 pounds are made available. Experiments nuide in Ohio show 

 that ground i)hosphates when used with manures will give a 

 return equal to that of superphosphates for the same dollars 

 and cents expended. AVhile they use very much less phos- 

 phoric acid, the cost is relatively greater. 



]Mr. Henri D. Haskins (of Amherst). Referring to the 

 basic slag question, have any samples come to your attention 

 that showed a low percentage of lime ? In other words, some 

 modera writers on basic slag claim that material made with 

 silica makes the phosphoric acid more available. In Massa- 

 chusetts we have not run across any of that product. 



Dr. Voorhees. AVe have not. 



