HISTORY OF THE AMERICAN MENHADEN. 245 



This leads us to consider tbe values of nitrogen and phosphoric acid 

 in different forms of combination. In general, it may be said that nitro- 

 gen is in its most readily available forms in sulphate of ammonia and ni- 

 trate of soda ; that it becomes quickly useful to the plant in Peruvian 

 guano, more slowly so in fish, dried blood, and meat scraps, and is very 

 long in becoming available in leather scraps, hoof and horn shavings, 

 hair, and the like. Soluble phosphoric acid is ready for use at once. 

 The insoluble phosphoric acid of fish guano, meat, and finely steamed 

 bones, acts more or less quickly, but in coarse pieces of bone and in 

 bone black its action is very slow. In the South Carolina, Nevassa, 

 Canada, and other mineral and fossil phosphates, it is of comparatively 

 little value. 



The nitrogen and phosphoric acid in coarse fish scraps are less valua- 

 ble than in tine dry fish, for two reasons : they are more bulky to trans- 

 port and apply, and are less available to plants when applied. 



In 100 pounds of dry guano, there will be say, 10-15 pounds of water, 

 while 100 pounds of half-dry scrap will contain 40-50 pounds of water. 

 To get 100 pounds of dry matter will require on the average, say, 112 

 pounds of guano and 180 pounds of the half-dry scrap. 



Again, the finely ground fish distributed evenly and thoroughly 

 through the soil, is readily decomposed, and thus conveyed where the 

 largest number of roots may have access to it and its materials will be 

 available to the roots when they find it. But the coarse scrap cannot 

 be as well distributed either when it is applied or by natural agencies 

 afterward, less roots will get at it, and when they do find it they will not 

 be able to use it as well as they could the more finely ground and better 

 decomposed guano. Less of the coarse scrap will enure to the benefit of 

 the first crop; and of that which is left over, the phosphoric acid will 

 remain in the soil for subsequent crops, but more or less of the nitro- 

 gen will in the process of decomposition be set free and escape into the 

 air, or be leached away by soil- waters beyond the reach of plants, or fixed 

 in unavailable combinations in the soil and thus lost to vegetation. 



A great deal has been said about the relative values of fish and Peru- 

 vian guano. The following table gives the results of experiments bearing 

 upon this point. The experiments were made upon twenty different beet- 

 sugar farms in and about Germany. The general plan and the details 

 were the same for all. They were carried on by intelligent farmers, 

 under the guidance of Dr. Grouven, director of the experiment station 

 at Salzmiinde in Prussia. The figures represent the value in German 

 thalers of the increase in yield over unmanured plots, taking into 

 account not only the increase of the manured crop, but the after effect 

 during two succeeding years. The fish guano was the Norwegian, 



