TILSTORY OF THE AMERICAN MENHADEN. 249 



What gives the vahie to these waste products is chiefly their nitrogen 

 compounds. 



Of late the importance of animal wastes, flesh, meal, dried blood, and 

 fish has come to be understood, and a good many accurate experiments 

 have been made to test their digestibility, their nutritive value, and 

 that of the manure produced from them. This will be explained in 

 the following section, paragraphs 314-325. I will here only refer in few 

 words to the results of a late series of experiments by Wildt, at Froskau, 

 and by Kellner, at Hohenheim, with Norwegian fish guano fed to sheep. 

 It appears that sheep digest the most of the nitrogenous material of the 

 flesh, and a large part of that of the bone. What is not stored away 

 in the body of the animal is excreted as urea, one of the most valuable 

 forms of nitrogen for plant food. Only a small part of the phosphoric 

 acid is digested, but the remainder is left in a very finely divided form, 

 and hence much better for a manure. Kellner discusses the various 

 methods employed for making the ingredients of fish more available 

 for manure. Treatment with acid and caustic alkalies is unsatisfactory. 

 Fermentation with urine is much better ; but the most convenient and 

 profitable way he concludes to be that of passing it through the diges- 

 tive organs of domestic animals. 



Practical conclusions. 



313. One very great obstacle to the profit from using fish as manure is 

 the fact that it contains only nitrogen, phosphoric acid, and lime, and 

 does not supply the other soil ingredients of plant-food. Where potash is 

 wanted the fish cannot suffice. Illustrations of this are only too abun- 

 dant. I have only to look out of the window where I write to see in the 

 distance a farm whose proprietor, some time ago, applied fish to one of 

 his fields at the rate of nearly a ton to the acre, hoping to obtain a 

 good crop of hay. In spite of this heavy and costly dressing the grass 

 failed. At my suggestion he tried a series of experiments with differ- 

 ent fertilizers to test the deficiencies of his soil. Wherever potash 

 salts were used the crop was good ; without potash it failed. The best 

 results were obtained with a " complete " fertilizer, containing nitrogen, 

 phosphoric acid, and potash, such as could be made from fish and pot- 

 ash salts. The recognition of facts like this often makes the difference 

 between good profit and ruinous failure in farming. 



The large amount of nitrogen in fish makes it a "stimulating" ma- 

 nure. It helps crops to get more of the food contained in the soil, and 

 thus to "exhaust" the immediately available supply. Farmers often 

 complain that fish, like Peruvian guano, wears out their land. In Maine 

 they talk of laud that has been " herringed to death." In Connecticut 

 we often see grasses leaving and sorrel coming in after such fertilizers 

 are used. Some good farmers say their soil gets hard and "caked" 

 after continuous use of fish. The remedies are, tillage and use of other 

 manures, ashes, lime, potash salts, bone, yard manure, muck, and so on. 



