196 



EXPERIMEXTAL ^FARMS 



2 GEORGE V.,. A. 1912 



pared, Porphyra laciniata is by far the richest in nitrogen and Laminaria longicruris 

 the richest in potash. In phosphoric acid, the percentage of which is always low in 

 sea-weed, the differences are not of the same economic interest. 



The difference in total ferttlizing value of the sea-weeds has been brought" out 

 by assigning to their nitrogen, phosphoric acid and potash the prices given to these 

 elements in commercial fertilizers, and the results of the calculation give figures 

 ranging from $1.27 to $3.86 per ton. 



Sea-Weed — Composition of Dry Matter. 



In the above table, the composition of the dry matter of the sea weeds is given. 

 Nos. 1 and 4 are fairly similar as regards organic matter and ash, and the same may 

 be said respecting Nos. 2 and 3. In the former group the ash constitutes about one- 

 third and in the latter about one-fourth, of the dry matter. 



The nitrogen-content of the dry matter varies greatly, and consequently the air- 

 dried sea weeds would possess widely different values from the standpoint of a nitro- 

 genous fertilizer. Porphyra laciniata is exceptionally high in nitrogen, while Lamin- 

 aria longicruris contains twice as much as Ascophyllum nodosum, which is the poorest 

 of the series. 



In phosphoric acid the first three members of the series are much alike, contain- 

 ing an amount approximately one-fourth that in the Laminaria. Sea weed is not 

 generally regarded as a phosphatic fertilizer, though no doubt its ready decay in the 

 soil makes the small amount of phosphoric acid contained quickly available and hence 

 valuable. 



Sea-weed is essentially a potassic manure, though, as we have seen, it also fur- 

 nishes a notable amount of nitrogen. The percentages of potash in the dry matter of 

 the specimens analysed, it will be observed, vary very considerably, from 2-48 per cent 

 in the Ascophyllum to 13-21 per cent in the Laminaria, the latter apparently being 

 an exceptionally high result. 



The fertilizing value of sea-weed is enhanced by its ready decomposition in the 

 soil; it quickly liberates its constituents in forms available for plant nutrition. 

 Though furnishing a considerable amount of organic matter, its decay does not prob- 

 ably add much to the humus-content of the soil, so complete may be its decomposition. 

 ■ For the reason that its plant food is so readily available, there is no necessity for allow- 

 ing it to rot before application to the soil. Little loss, however, can ensue if compost- 

 ing is resorted to by mixing it. with good manure, muck or other material which would 

 absorb the decomposition products. On the whole, however, its immediate incorpora- 

 tion with the soil would appear to be the best plan. 



