FISH MANURE. Dried and ground fish or fish guano is a valuable fertilizer obtained main ly front two sources: (1) The refuse front fish packing and canning establishments. and (2) the pomace from the extraction of oil from fish— in America, chiefly the menhaden. The product from the latter source is especially rich in fer tilizing constituents, containing from 7 to 8 per cent. of nitrogen and 6 to S per cent. of phosphoric acid. The availability of the nitro gen is nearly as great as that of dried blood and tankage. The phosphoric acid is frequently more available than that in other organic matter. The availability of the fertilizing constituents depends largely upon the proportion of oil pres ent. A considerable proportion of the latter delays decomposition ill the soil. and thus reduces the availability. The oil is removed and the fish prepared for use as a fertilizer on a commercial scale by cooking with water in tanks heated with steam. The oil rises to the surface of the water and the two are drawn off together. The residue is pressed, dried, and ground. In sonic eases, after the first pressing. the material is subjected to the action of steam under pressure and sul phuric acid (5 per cent.) to render the fertilizing constituents more available. The uncooked fish is sometimes treated directly with sulphuric acid to prevent offensive decomposition and to increase the availability of the nitrogen and phosphoric acid.
Fish manures are prepared and used in con siderable quantities, especially along the north eastern coast of America, in Norway, and other regions where the supply of material is abundant. Fish manure is exported in considerable quauti ties from Norway.
In localities where it can be readily obtained from fishermen, fish-scrap is frequently used without preparation of any kind. Naturally, this product is very variable in composition, the nitrogen ranging from 2.5 to 8 per cent. and the phosphoric acid from 2 to 6 per cent. The fertiliz ing constituents of this material are less available than those of the dried and finely ground fish. The whole fish are also sometimes used as a manure, either directly or composted with other materials. It is stated in Bradford, History of Plymouth Plantation (Boston, 1856), that the Indian Squanto first taught the New England colonists to use the menhaden as a fertilizer for corn, instructing them to put the fish under the hills at the time of planting. (See also AND MANURING.) Consult: Voorhees, Fertilizers (New York, 1898) ; Aikman, Manures and the Principles of Manuring (Edinburgh, 1894) ; Storer, Agriculture (7th ed., New York, 1897).