202 ON THE COMPOSITION AND VALUE OF KELP. 



supply of the inorg-anic ing-redients required by our crops, 

 while the larg-e amount of salts of potash and soda which 

 enters into its composition, point it out as i)eculiarly adapted 

 for the nourishment of our potato and turnip crops. The 

 sample examined, from containing- but a small amount of 

 soluble silica, would not be so well adapted for the growth 

 of the corn crops, except in situations where a sufficient sup- 

 ply of soluble silicates were already present in the soil ; biit, in 

 g'eneral, the kelp of our coasts contains a much g'reater 

 amount of silicates, from the common practice of fusing" a 

 quantity of sand with the melted ash — a practice which, for 

 the sake of increasing- the weig-ht, is carried to a shameful 

 extent by the kelp-burners. As kelp affords us, as I have 

 shown, a convenient source of the most important elements 

 of plants, and in a convenient portable form, so that we can 

 readily carry it into the interior of the country, and applj' it 

 in situations where its action would be still more beneficial 

 than in the neig'hbourhood of the sea, it is, I conceive, of 

 importance that some experiments should be instituted with 

 this substance, by such of my hearers as possess the oppor- 

 tunity. From several experiments, with diiferent samples of 

 kelp, I find that a hundredvveig'ht of that manufactured on 

 our coasts usually contains between 50 to 70 lb. of salts 

 soluble in water, which would aftbrd the plant, from its for- 

 mation, a ready prepared supply of nutritious materials, 

 while the alkaline silicates and salts of lime, magnesia, &c., 

 would continue to exercise a beneficial influence upon the 

 fertility of the field, even beyond the present season. 



The averag-e produce of potatoes, in many districts in the 

 north of Ireland, I have ascertained by careful inquir}-, does 

 not exceed 350 bushels, or 10,600 lb. per Irish acre, an 

 amount of tubers which analysis shows us to contain about 

 190 lb. of matter extracted from the soil. The chief consti- 

 tuent of the ])otafco tuber is ])otash, an expensive article with 

 the manure dealer, 92 lb. of which is taken away from our 

 fields with every 350 bushels of potatoes that we send to 

 market. Now, half a ton of kelp, of the same character as 

 the sample examined, contains, as we have seen, about 

 92i lb. of that alkali ; so, by applying- that quantity of it to 

 a portion of g-round in which we have produced 350 bushels 

 of potatoes, we not only maintain its fertility, so fiir as it 

 depends upon the presence of that substance in the soil ; but 

 also g-ive it a supply of other matter which will be useful to 

 the succeeding' crops of the rotation ; for the amount of soda 



