history of the american menhaden. 265 



53. Summary. 



Fish as manure. 



326. The following is a brief recapitulation of the main points urged in 

 this article : 



1. The value of fish as manure is due mainly to its nitrogen and phos- 

 phoric acid. 



2. Taking into account composition, quality, and price, fish manures 

 furnish these ingredients more cheaply than any other class of fertilizers 

 iu the market except Peruvian guanos. 



3. The crops most benefited by fish manures are those which need 

 considerable nitrogen and pliosphoric acid, but are not especially helped 

 by mineral manures alone. Such are grass, grain, and corn. The same 

 is generally true of potatoes and garden vegetables, and sometimes of 

 roots. Leguminous crops, like clover, beans, and pease, are more bene, 

 filed by mineral manures, and get little good from the nitrogen of the 

 fish. 



4. Fish manures arequick and stimulating in their action. Their force 

 is soon spent and they often leave the soil in worse condition than be- 

 fore they were applied. This is, however, no argument against their 

 value. The remedy for such cases is to apply other materials, as ashes, 

 lime, potash salts, dung, muck, etc., with them. 



5. The proper soils for fish manures are those which are deficient in 

 nitrogen and phosphoric acid, and in which the stimulating effect of the 

 decomposition of fish may render other materials available for plant 

 food. Soils that have been treated repeatedly with fish, guano, phos- 

 phates, and bone are often overstocked with these ingredients and 

 deficient in potash. Many soils are originally poor in potash. To apply 

 fish on such soils and omit the lacking elements is to lose both fertilizer 

 and crop. The deficiencies of a given soil are best told by actual trial, 

 with different manures and crops. 



G. The general usefulness of fish manures will be increased by adding 

 to them phosphoric acid, in the form of bone or superphosphates, and 

 potash iu German potash salts. Fine steamed bone, that can be bought 

 for $32 to $45 per ton, or "plain" superphosphates, made from South 

 Carolina or Canada phosphates, and sold at $30 to $32 per ton, are 

 economical sources of phosphoric acid. The " 50 per cent, muriate," 

 sold at about $40 per ton, is one of the cheapest grades of potash 

 salts. Of the " ammoniated" superphosphates, a very few of the best 

 brands are sold at cheaper rates than it would cost the farmer to make 

 them. But inistead of buying medium and inferior articles, farmers will 

 do better to buy the materials and mix them at home. 



7. The best form of fish manures is the dry-ground fish guano freed from 

 oil. The water and oil add weight and bulk without increat«ing value. 

 The coarse fish-scrap cannot be thoroughly spread, is not easily diffused 

 by the water iu the soil, is reached by few roots, and becomes slowly 



