114 SEA BAMBOO AS A SOURCE OF POTASH. 



Cattle are declared to thrive excellently upon the grass resulting from 

 sea-manure and in Jersey particularly this fact is turned to account while 

 parsnips and turnips are cultivated hy its aid, sup'emented by cow manure; 

 for mangolds it is also largely used; to potatoes, however, it is said to 

 impart a disagreeal)le flavour. The practice is to plough the fresh seaweed 

 two or three inches into the soil in autumn (ir winter, following it up 

 in the spring by trench ploughing with 20 to 30 tons per acre of farm- 

 yard manure." 



On the other hand, it is a matter open to grave doubt 

 whether it would be |>ossible to profitably apply the dried kelp 

 at any place necessitating transport for any great distance, which 

 would mean that the scope of its utility as a green manure would 

 be limited to those cultivated areas which are adjacent to the 

 coast where the kelp is obtained. The alternative method would 

 be to burn the weed at a low temperature, and either use it as 

 the ash or after leaching out and evaporation of the salts. It 

 is of interest to note that the trunk portion of the thallus dries 

 rapidly in warm weather to a hard brittle condition which would 

 lend itself to rapid incineration. During the process otf drying 

 a salt effloresces from the tnmk, which is apparently very much 

 simpler in composition than the salt obtained after ashing and 

 leadiing. I am indebted to Mr. E. V. Flack for having analysed 

 a small i>ortion of this efflorescence, which ga\'e the following 

 figures : — 



Total soluble salts 82.56 per cent. 



Chlorine 39-73 per cent. 



Carbon dioxide Trace. 



Sulphuric oxide Nil. 



Potash 50.48 per cent. 



Soda (calculated) 1.40 per cent. 



Equivalent to 80 per cent, potassium chlor- 

 ide and 2.6 per cent, sodium chloride. 



It will be obvious that if a method of ashing after drying 

 were adopted, it would be necessary to take precautions not to 

 exix)se the kelp to rain, and thus lose the valuable constituents. 

 Probably the best results in fertilization would be obtained by 

 admixture of the ash with superphosphate ; the immediate efifect 

 of this mixing with the superphosi)hate would be to cause a 

 reversion of a portion of the water-soluble jihosphoric oxide in 

 the latter, but this would not be very serious ; on the other hand, 

 the mixing w^ould prove beneficial in the end by neutralising sottie 

 of the free acid invariably found in superphosphate, which is 

 one of the chief reasons, if not the chief reason, for opposition 

 to the use of that fertilizer .alone on sour or acid soils. It 

 must be remembered, too, that the chief constituents of the ash 

 are the chlorides of potassium and sodium, which are regarded 

 as injurious for some crops, such as tobacco; generally speaking, 

 however. I do not anticipate that there will be any very great 

 objection to their use, as extended use has already been made 

 in this country of kainit, a fertilizer which contains similar salts, 

 though not nearly so rich in potash. 



