1910.] Composition of Seaweed and Use as Manure. 465 



the rocks. Analysis of the Thanet sample which was thrown 

 up by the tide showed the following constituents : — 



Fucus serratus 



597 per cent. 



Glyceria maritima and Salicornia herbacea ... 



4'3 „ 



Laminaria 





Ulva ... ... ... ... 



1 '4 



Fucus vesiculosus ... 



0:6 



Sea mat 



I '2 



Miscellaneous debris 



3Q'3 



The composition of various mixed samples as gathered is 

 given in Table III. 



Table III. — Percentage Composition of Fresh Seaweed as 



Gathered. 





Thanet. 



Scotland (i). 



Jersey (2). 



United States 

 (average of 



many 

 analyses). 



Canada (two single 

 analyses). 



Water ... 



75-00 



77'4I 



77'5 



81 - 5 



63-49 



79-23 



Organic matter ... 



14*45 



1630 



l8l 





27*93 



15*23 



Nitrogen 



0-48 



0'54 



0"27 



073 



o*47 



017 



Potash 



1 *oo 



1-24 



o-8o 



1-50 



2 -02 



076 



Phosphoric acid ... 



O*02 



C09 



0'12 



0-18 



o-ii 



0*04 



(1.) Mr. Hendrick's results. (2.) Mean of Mr. Toms' results. 



We may summarise all these British results as follows : — 



Wet weed as gathered. 



Average. 



Per Cent. Per Cent. 



Water 70 to 80 75 



Organic matter 13 to 20 18 



Nitrogen... ... .. ... ... 0-3 to o"8 0*5 



Potash o-8 to I '5 1*2 



Phosphoric acid ... ... ... 0*02 to 0-17 0-09 



A considerable amount of water is lost on drying in the 

 air, and if the weed has not been washed by rain in the mean- 

 time, its value is increased four, five, or even six fold. 



It is difficult to form an estimate of the money value of 

 seaweed to the farmer. The fertilising materials present in 

 1 ton of seaweed possessing the average composition would 

 cost 8s. to 10s. if purchased from a dealer. This value is 

 arrived at by allowing 12s. for each per cent, of nitrogen, 4s. 

 for each per cent, of potash, and 3s. for each per cent, of 

 phosphoric acid. No account is taken of the sodium, calcium 

 and magnesium salts, which on most soils, but especially 

 light soils, would be distinctly beneficial; nor is any allow- 



