UTILIZATION OF THE FISH WASTE OF THE PACIFIC OCEAN. 59 



From the results of analyses recorded above the following gen- 

 eralizations have been made : 



(1) No definite quantitative relations exist between the different constituents 

 of kelp. 



(2) The potassium content of Nereocystis is greater than that of Microcystis. 



(3) The potassium content of northern kelp is higher than that of southern 

 kelp. 



(4) There is no positive difference in iodine content between northern and 

 southern kelps. 



The following conclusions also seem justified: 



(5) The proximity of the mouth of a fresh-water stream has no appreciable 

 effect on the potash and nitrogen content of kelp. 



(6) There are no essential differences between the potash and nitrogen con- 

 tent of fronds and stipes. 1 



KELP AS A FERTILIZER. 



In the British Isles kelp has been used as a fertilizer for centuries. 

 So highly was it valued that lands carrying kelp -harvesting privi- 

 leges were especially valuable. In Xew England, also, kelp or sea- 

 weed has found favorable use as a soil amendment. In Alaska, espe- 

 cially on Kodiak Island, near the village of Kodiak, and in the 

 neighborhood of Skagway, it is used in like manner, on the former 

 island particularly in fertilizing potatoes and in the latter region 

 on truck gardens. 



The Pacific kelps are markedly different from the seaweeds of the 

 Atlantic coast, especially in their very much greater size and their 

 relatively large content of potassium chloride. It is these two quali- 

 ties that give them especial importance as a possible source of fer- 

 tilizer materials. 



In the regions mentioned kelp has been applied to the soil as a 

 mulch in its green state, or, better, after it has been cured by drying 

 in the sun, or rotted by being allowed to stand in heaps. 



For several years past kelp has been harvested mechanically near 

 San Pedro, Cal., and shipped in the crude, undried condition to the 

 ranches and orchards of that part of the State. As the green kelp, 

 after draining, contains about 85 per cent water, its content of potash 

 and nitrogen are about 2.6 per cent and 0.3 per cent, respectively. 

 These values are obtained by calculating back from the values estab- 

 lished on the dry basis to that of a content of 85 per cent water. 



The manurial value of green kelp, as compared with a number of 

 other materials commonly used as fertilizers, is brought out in the 

 following table : 2 



1 Cameron, Kelp and Other Sources of Potash, J. Frank. Inst., October, 1913, p. 363. 



2 Cameron, loc. cit., p. 377. 



