1889.] PUBLIC DOCUMENT — No. 4. 33 



fertilizers should contain at least ten per cent of potash, and 

 I do not care to have more than ten per cent of phosphoric 

 acid. 



Question. What was the crop ? 



Professor Whitcher. Corn , in the cases I have just given. 

 I find the same thing true of grass : more potash, more grass ! 



Question. Will you please explain the diiference be- 

 tween muriate and sulphate of potash ? 



Professor Whitcher. One is potash combined with 

 hydrochloric acid ; the other, with sulphuric. This is the 

 chemical difference. So far as their use is concerned I do 

 not know that I can tell you the difference. I should gener- 

 ally use muriate ; but I believe it is contended that the 

 quality of potatoes is affected by one more than the other. 

 I am not certain which is said to give the best quality, but 

 think it is the muriate. I have looked more to quantity than 

 quality in the matter ; perhaps too much so. 



Benj. p. Ware of Marblehead. I think there is one point 

 that is not quite clear. You have shown that bone, dissolved 

 by sulphuric acid, becomes soluble ; that is, it contains 

 plant food. Now, do I understand by that that ground bone 

 contains no plant food ? I would also like to ask whether 

 there is any plant food available from South Carolina rock or 

 iron slag without previous preparation ? 



Professor Whitcher. I did not intend to give the im- 

 pression that there was no plant food in bone. Phosphoric 

 acid is plant food wherever it is. It may be available, or it 

 may not be. In bone and South Carolina rock it is sparingly 

 soluble ; in the latter perhaps not at all. 



Now, if you apply a large quantity of bone, it is slowly 

 decomposed in the soil, and in this way plants get a partial 

 or full supply according as the amount of bone used was 

 large or small. But I do not believe in this method of fer- 

 tilizing. I would use fertilizer in such a form that I could 

 get the most of it back in a single year. Fertilize for the 

 present crop, not for the next ten years. Fertilizers are the 

 farmer's raw material. From them he manufactures farm 

 products. Get the best raw material, and use it as quickly 

 as possible. Turn fertilizer into crop, crop into money, and 

 do it quickly. 



