110 Fertilizers 



mussels decay rapidly, and serve as a fairly good source of 

 nitrogen; and since this product is twice as rich in this 

 constituent as average yard manure, it is well worth the 

 expense of handling. 



Lobster shells are also a waste of considerable impor- 

 tance, since they can be obtained at a very low cost, often 

 for the carting. They contain, in their dry state, an aver- 

 age of over 4 per cent of nitrogen, 3 per cent of phosphoric 

 acid and about 20 per cent of lime. 



These products, of course, are not to be depended 

 upon for the entire supply of constituents to crops ; they 

 are mainly useful in improving the natural quality of the 

 soil by building it up in vegetable matter containing 

 nitrogen. Their best use requires the addition of the 

 minerals from other sources. 



Seaweed. 



Seaweed, already referred to in the discussion of potash 

 salts, is held in high esteem in the coast states as a manurial 

 product. In Connecticut, Rhode Island and New Jersey, 

 the use of seaweed as a fertilizer is very general. In 

 Rhode Island the annual value of the manure from this 

 source has been estimated to be as high as $65,000. 



In its fresh state it contains from 70 to over 80 per cent 

 of water, and is thus economically used in that condition 

 only near the shore. It is frequently spread out in thin 

 layers and dried, in which condition it can be profitably 

 transported considerable distances. 



Seaweeds of different kinds differ in their content of 

 the fertilizing constituents. Certain of them show a rela- 

 tively high content of nitrogen, and others of potash, and 

 they furnish more of these constituents than of phosphoric 

 acid. All seaweeds contain considerable salt, though if 



