PLANT NUTRITION. 43 



materials cost something loss than $70 per ton. Sulpliate of 

 ammonia is about $100, potash from $30 to $10, and phosphoric 

 acid from $40 to $60 per ton. The material is dear, and yet after 

 the supply of barn-yard niannre and compost made on the farm is 

 exhausted, I consider this the cheapest manure that can be 

 bougiit. A ton of the material is enough to manure four or five 

 acres in a way which is equivalent to the use of six or seven cords 

 of barn-yard manure to the acre. I have said it was the cheapest 

 manure. Let us see. Last year it cost us $21 to make 50 bushels 

 of corn with the natural proportion of stalks. It may cost a little 

 more or a little less this year. You say at once that is 42 cents 

 per bushel. But when I harvested my 50 bushels more than the 

 natural yield, I harvested 94 bushels of shelled corn from the acre, 

 and the stalks are worth $8 per ton. I can make money at that 

 rate with corn at present prices, and stalks at $8 to $10 per ton. 

 The soil will produce something of itself, and it ought to produce 

 enough to pay for the cost of cultivation, the taxes, and the 

 interest on the land. If it won't do this the farmer has no busi- 

 ness to own it. The amount produced by the fertilizer is the 

 amount above this natural production. In our experiments the 

 natural production was ascertained in each case by planting a 

 piece of unmanured land of like size and quality. 



Mr. Lyman II. Winslow of Nobloboro'. Suppose you had a 

 piece of land that j'ou intended to plant with corn, and had manure 

 carted on it which you regarded as sufficient dressing, would you 

 apply this fertilizer to that land ? 



Prof. Stockbridge. I would do this : Plant the land as you 

 have proposed, getting if you like a little sulphate of ammonia to 

 start 3'our crop ; then plow up some of your worn-out land that 

 won't bear anything and raise from seventy-five to one hundred 

 bushels of corn to the acre, by the use of chemicals. 



Prof. Stockbridge's Formulas. 

 The following are the formulas of Prof. Stockbridge for the 

 preparation of his various special fertilizers : Column 1 gives the 

 quantity of the crop, including the natural proportion of roots, 

 stalks, leaves, pods, &c., to be produced in excess of the natural 

 production of the soil. Column 2 gives the quantity of nitrogen 

 necessary to produce this given quantity, and 3 the form in which 

 it may be obtained ; 4 of the second element, potash, and either 

 5 or 6 the form in which it may be obtained ; 1 of the third ele- 



