252 FISHERY INDUSTRIAL PRODUCTS 



Liquid Fish Fertilizer 



Before the value of fish meal for poultry feed was fully appreciated, 

 most fish meal was used as a fertilizer. Today the value of fish meal for 

 feed is so much greater than for fertilizer that it is all used as a feed. In 

 recent years, however, a small quantity of fish solubles or ''liquid fish" 

 has been diverted to use as a fertilizer where for some special reason an 

 organic-type fertilizer in liquid form is desired. This usage has, for ex- 

 ample, appealed to the home gardener as providing an easily used mate- 

 rial which can readily be sprayed or poured on flowers or other home 

 plants. These liquid fish fertilizers are considerably more expensive than 

 comparable liquid chemical fertilizers which are made from inorganic 

 sources of nitrogen, phosphorous, potassium, and trace metals. The only 

 advantage to the liquid fish fertilizers lies in the slower absorption by the 

 plants and slower leaching by rain or other water of the organic material 

 than is the case with the inorganic liquid fertilizers. 



For preparation of liquid fertilizers, ordinary fish solubles, possibly 

 centrifuged to remove some of the loosely suspended particles which 

 otherwise settle in time to the bottom of the container, are treated with 

 some odor-masking agent such as oil of citronella and bottled. Such a 

 liquid fish fertilizer has a poor balance of components for most garden 

 use because the ratio of nitrogen to other important elements (phos- 

 phorous and potassium) is much too high. Such liquid fish fertilizer may 

 be fortified by addition of inorganic phosphorous and potassium. In other 

 cases a liquid fish is prepared by digestion of the solid fish material with 

 potassium hydroxide, neutralizing the excess alkali with phosphoric acid. 

 Such a process results in boosting the deficient phosphorous and potassium 

 to a more satisfactory level. 



LITERATURE CITED 



1. Anon., Pacific Fisherman 47, No. 3, 57(1949). 



2. Bethe, Z. Physiol. Chem. 20, 472(1895). 



3. Decker, W. E., Org. Finishing 14, No. 7, 11(1953). 



4. Gordon, Bernard L., Maine Coast Fisherman 12, 10(1958). 



5. Smith, Paul, "Glue and Gelatin," New York, Chemical Publishing Co., 1943. 



6. Taylor, Hardin, "Pearl Essence: Its History, Chemistry and Technology," Docu- 



ment 989, Washington. U.S. Bureau of Fisheries, Report of the Commissioner of 

 Fisheries, 1925. 



7. Trcssler, Donald, and Lemon, J. M., "Marine Products of Commerce," New York, 



Reinhold Publishing Corp., 1951. 



