110 OF FERTILIZERS. 



its cohesion ; it becomes more friable and more readily 

 pulverized than by the most careful ploughing. In a 

 sandy soil, coherence may be given. Each stem, of the 

 green plants ploughed in, opens, by its decay, a road by 

 which the delicate rootlets of the future plant may ramify 

 in all directions to seek their food. 



308. Kelp and rock-weed are very valuable as a ma 

 nure. They contain a good deal of nitrogen and a 

 large proportion of alkaline and earthy salts, and, as 

 they undergo decomposition more rapidly than other 

 green manures, so their effect upon vegetation is, propor 

 tionally, much more powerful, but it is also much less 

 lasting. The slender, grass-like sea-weed, also called eel- 

 grass, has very little value as a manure, as it has little 

 substance, and yields very slowly to decay, but is still 

 valuable for its mechanical effects upon heavy soils. 



Kelp and rock-weed may be ploughed in, like other 

 green manures, but this should be done as soon as possi 

 ble, or, if this is not practicable, they should be stratified 

 with earth and lime, in order to convert them into a com 

 post, or they may be mixed with ordinary manure. 



These sea-weeds act beneficially on all ordinary crops. 

 If spread upon grass in spring or early summer, they 

 promote its growth ; and a crop of grain subsequently 

 obtained from such a soil, is said to be much improved, 

 at least in quantity, for the quality is thought to be dete 

 riorated. In the north of Scotland, farmers prefer kelp 

 and rock-weed to any other manure for cabbages. They 

 form an excellent manure for fiax and hemp, the flax 

 obtained being improved thereby, both in quantity and 

 quality. Rye, oats, turnips and clover are benefited by 

 that manure. Their action upon vegetables is immediate 



