140 BOARD OF AGRICULTURE. [Pub. Doc. 



should be called distinctly to the fact that, in taking up 

 worn-out land, it would not be wise to depend entirely at 

 the outstart upon these forms of phosphoric acid. In such 

 instances, particularly if crops are grown which mature 

 early, superphosphate should be used. Upon land leased 

 for two or three years, if one considers the question only 

 from the stand-point of the one hiring the farm, the same 

 advice would apply. It seems probable, however, that, in 

 renovating land upon one's own farm, the soil may be profit- 

 ably stocked to a certain extent, preferably before seeding 

 to grass, with bone or floats, depending upon their relative 

 prices. As has already been stated, in the Rhode Island 

 experiments a given amount of bone gave a greater yield 

 of hay in a series of years than the same quantity of phos- 

 phoric acid as floats, this being due perhaps to some extent 

 to the nitrogen of the bone. This is not enough, however, 

 to warrant the use of bone instead of floats without first 

 taking a look at the financial side of the question. 



Let us assume that fine-ground steamed bone costs $23 

 per ton, and that it contains 23 per cent of phosphoric acid 

 and 3 per cent of nitrogen. If we reckon the value of the 

 60 pounds of nitrogen in a ton of bone at 12|- cents per 

 pound, the price of nitrogen in nitrate of soda, it would 

 amount to $7.50, leaving $15.50 as the cost of 460 pounds 

 of phosphoric acid. Assuming, again, that floats may be 

 bought at $10 per ton, and that they contain 28 per cent of 

 phosphoric acid, we find that in this case 560 pounds of 

 phosphoric acid costs but $10, or at the rate of 1.78 cents 

 per pound. At this rate, the $15.50 spent in buying the 

 460 pounds of phosphoric acid as bone would have bought 

 870.8 pounds of phosphoric acid in the form of floats, or 

 311 pounds more. The question cannot be dismissed here. 



At the Connecticut station Johnson and Jenkins find that 

 the immediate assimilability of the nitrogen of finely ground 

 bone is less than 20, calling that of nitrate of soda 100. 

 This is certainly a poor showing for the nitrogen of bone, 

 and without doubt the cumulative action of a series of 

 years would make a far better record, time being thus given 

 for the bone to more completely decompose. In fact, other 

 experimenters give it a value not far from 50, placing the 



