No. 7. DEPARTMENT OF AGRICULTURE. 459 



it and then plant corn, and they say they have been getting good 

 results from it, but I think where they used it with manure they got 

 better results from it than where they used it without and they are 

 now averaging |S to -flO per year for every |1.28 worth that they put 

 on. In the last five years they have averaged, I think, about |8 for 

 11.28 supply. 



MR. FENSTERMAKER: I would like to inquire of the gentle- 

 man whether the spreading of the manure in floats will help to re- 

 tain the ammonia? 



PROF. HOPKINkS: No, sir; it will not. 



MR. SCHWARZ: In your report you put nitrogen at 15 cents, 

 phosphorus at 12 cents and potassium at G cents; why do you do 

 that? 



PROF. HOPKINS: Because that is what they cost. Not phos- 

 phoric acid, but phosphorus. Now, a lOO-bushel crop of corn re- 

 quires 2.3 pounds of ])hosphorus — of this rock phosphorus. If you 

 will put on 100 pounds of phosphorus with every load of manure, 

 you will get 10 pounds to the acre, that is, 2 pounds to the acre for 

 five years, isn't it? And then, if the land does not wash away, you 

 you will have your 100-bushel crop of corn and your land will be 

 richer at the end of the five years than it was before. 



QUESTION: You mean that it is richer at the end even if the 

 corn crop is taken off? 



PROF. HOPKINS: I do. 



QUESTION: If you plant corn one year, and oats the next, and 

 wheat the next, and then grass for the next three years, what treat- 

 ment does the land need? 



PROF. HOPKINS: That is a six-year rotation. In that case we 

 put on 1,200 pounds of phosphorus, and if yoa had manure on twice, 

 we divide it, and put (300 pounds to the acre each time. You will 

 not need to put on that if the land gets rich, but if the land becomes 

 deficient in phosphorus, we want to put on more than we take off, 

 because we want our land to get rich. When we get the land rich 

 then we put on just what we take off. 



DEPUTY SECRETARY MARTIN: Is acid phosphorus injurious 

 to the land? 



PROF. HOPKINS: I don't think it is as injurious to the land as U 

 is to the pocket-book. It does tend to increase the acidity of the 

 soil, but we can put ground lime on it and lime tends to correct 

 that acidity. I think the largest objection to it is the cost. I would 

 like you to stop just a moment and consider these materials. We 

 take a ton of phosphoric rock, carrying with it 12| per cent, of the 

 actual element phosphorus; that is 250 pounds to the ton. That is 

 the phosphoric element, worth 12 cents per pound, not the phosphoric 

 acid. The phosphoric rock you can get for |8 on cars. Now, you 

 let a manufacturer take this, and he will put it with a ton of sul- 

 phuric acid and for |16 he has two tons, which he will sell for 



