Orgfanic Manures 



into powder, or sometimes after the addition of lime 

 they are passed on into filter presses in which the 

 water is expressed and the solid matter compressed 

 into cakes. This sewage from which the greater 

 part of the soluble constituents has been taken still 

 contains fertilising matter to be employed with 

 success, in triennial applications, on sandy soils 

 where farmyard manure would be needed. Under 

 these conditions the fatty and soapy matters which 

 if used regularly and abundantly would be an 

 obstacle to the aeration and the permeability of the 

 soil will, in the time, be destroyed. The price of one 

 shilling a ton at which it is sold in some places 

 makes its use worth while. 



Seaweed. 



The use of seaweed is confined to the sea coast, 

 more especially the west, but as the English coast 

 line is of great extent, it is nevertheless of some 

 importance. It is derived from two classes of 

 marme plants — the genus Fucus represented by the 

 species which grow in the tract lying between high 

 and low water, which are much the poorer as manure, 

 and the genus Laminaria to which belong the 

 submarine plants which are brought up by the tide 

 and left exposed when it recedes. 



Seaweed, although really a complete manure 

 containing side by side with humus the different 

 fertilising elements necessary for crops, does not, 

 however, contain them in suitable proportions. It 

 is poor in phosphoric acid, and not sufficiently rich 

 in nitrogen, but it is rich in potash, and so rich in 

 chloride of potash (KCl) and soda (NaCl, common 



120 



