AQUATIC PEODUCTS AS FEETILIZEKS. 279 



that could have been said in its favor until very recently. Considered as a manure, 

 it was rejected by the farmers long ago. It has been tried and found wanting by 

 numerous generations of men. Still, on analysis it appears that eelgrass con- 

 tains a considerable proportion of fertilizing matters, and there can be no doubt 

 that it will be found amenable to proper treatment and will eventually be prized 

 as a manure. Besides 1^ per cent of nitrogen, air-dried eelgrass contains 1 per 

 cent of potash and 0.25 per cent of phosphoric acid. The ashes of eelgrass con- 

 tain 7 per cent of potash and 1+ per cent of phosphoric acid, which is about as 

 miTch as is contained in ordinary hoxise ashes from wood fires. The trouble with 

 eelgrass is, as was said before, that it will not rot in the soil. It must be coerced 

 in some way in order to make its fertilizing constituents available for crops. It 

 might be burned, for example, to ashes in order to get the potash and phosphoric 

 acid: or, much better, the organic matter maybe disorganized by composting the 

 grass with lime or with rockweed. That is to say, the eelgrass may either be 

 thrown into heaps, with layers of lime interpolated, in order to reduce the resisting 

 tissue to a manageable form, or it may be built into a heap, layer by layer, with 

 fresh rockweed or sea manure, and so subjected to destructive fermentation. 



It is quite impracticable to form a close estimate of the total quan- 

 tity of aquatic plants used for fertilizer in this country. The latest 

 returns of the United States Fish Commission show an output on the 

 New England coast of 75,000 tons, worth about $1 per ton, but these 

 figures probably do not show the total production. According to the 

 Rhode Island census of 1885, $65,044 worth of seaweeds were used in 

 that State alone during the census year, compared with a total of ^^ 

 $164,133 worth of "commercial" fertilizers. This reiDresents only a 

 small i^ei'centage of the total quantity obtainable, it being possible to 

 collect a thousand or more tons to the mile of that coast. The growth 

 of the plants is rapid, and rocks scraped Ijare may be covered with 

 kelp 5 or 6 feet long the following year. 



