34 BULLETIN 150, U. S. DEPARTMENT OF AGRICULTURE. 



The salmon scrap has a lighter color and more pleasant odor 

 than the menhaden scrap. This, again, possibly does not concern 

 its fertilizing value, though there is a remote possibility that it 

 may affect its demand in the trade. It is said that some agricul- 

 turists appraise the value of fertilizer materials by the disagree- 

 ableness and strength of their odor. On the contrary, it is a better 

 established fact that considerable prejudice exists against fish scrap 

 on the part of common carriers and the public in general because 

 of its odor. Since nothing is to be lost and something is to be gained 

 by reducing the disagreeable odors of fish fertilizer, the point men- 

 tioned is favorable to the salmon scrap. The better smell of the 

 latter is due most probably in greatest measure to the fact that it 

 is dried at moderate temperatures and is not scorched, as inevitably 

 must happen in the hot-air driers as now operated on the Atlantic 

 coast. It also is true that the menhaden scrap is dried in a stream 

 of hot gases generated in a soft-coal fire; the soot from this doubt- 

 less contributes likewise to the dark color of the product. 



Another point of difference between the salmon and menhaden 

 scrap is introduced by the occasional acidulation of the latter. The 

 addition of sulphuric acid to the scrap is practiced most generally 

 to disinfect the undried but freshly cooked and warm "pomace," 

 and to render it unfit as a breeding place for flies. This is resorted 

 to, as a rule, only when the scrap is being produced at a rate greater 

 than that at which it can be dried. The acidulation frequently is 

 followed by drying. The addition of sulphuric acid to the scrap 

 is supposed to be beneficial in that it " fixes the ammonia " and 

 renders soluble the phosphoric acid of the calcium phosphate con- 

 stituting the bones. While it induces a disintegration and pulveri- 

 zation of the scrap, and enables the producer to sell the bone phos- 

 phate present as soluble phosphoric acid, at the same time it acts 

 as a diluent of slight, if any, fertilizer value, with no rating on a 

 fertilizer basis. 



In the foregoing comparison of scrap from salmon and menhaden, 

 respectively, it is not intended to convey the idea that the menhaden 

 scrap for fertilizer purposes is inferior to that from the salmon. 

 It is believed that the ammonia and phosphate of the one is as 

 valuable as that of the other. 



FISH SCRAP AS CATTLE AND POULTRY FEED. 



To discuss fish scrap from any point of view other than that of 

 fertilizer, perhaps, is beyond the province of this report. It should 

 be pointed out here, however, that with such fertilizer materials as 

 dried blood, abattoir tankage of high grade, cottonseed meal, and 

 fish scrap, it is better agricultural practice to feed these to stock, 

 provided, of course, that all barnyard manures be conserved care- 



