21G ON THE RELATIVE 



was exactly douLled. The g-uano in tliis instance contained, 

 according- to analyses, 30 per cent, of phospliate of lime, 

 with mag'nesia, oxalate of lime, and 25 per cent, of ammo- 

 niacal salts. From this he was led to believe that the 

 inactivity of Liebig-'s manure on Carnwinick, was owing- to a 

 deficiency of azotized matters in the soil, as well as the want 

 of a sufficient quantity of phosphate, for when both were 

 added in the g-uano used in Mr. Gilbert's experiment, the 

 crop was equal to that produced by 25 loads of g-ood farm- 

 yard manure, and su])erior to that ])roduced by 24 bushels of 

 bone-dust. In Nos. 7 and 8, in the last-mentioned experi- 

 ment, they had a striking- proof of the utility of combining* 

 nitrog-enized substances with the phosphates when absent in 

 the soil, for the addition of 100 lb. of nitrate of soda in one 

 case, and the same weight of nitrate of potash in another 

 case, produced an increase over No. 1, when the bone-dust 

 was used without these salts, of double the produce. Both. 

 these salts furnish nitrogen to the plant as well as an alkali^ 

 and hence their value in addition to the bone-manure, on 

 a soil previously exhausted of these materials, — 100 lb. of 

 each furnishing- about 19 lb. of nitrog'en. The turnip crop 

 can be cultivated, perhaps, with a smaller supply of nitro- 

 g-enized substances than almost any other, particularly when 

 compared with Avheat, barley, beans, &c. Science now 

 taught them that the atmosphere yields its portion to the 

 growth of plants, as well as the soil. Hence the larger the 

 vegetable surfaces they could present to the atmosphere in 

 the shape of luxui-iant stem and foliage, the more they should 

 absorb from it ; and this was partly eftected by the organic 

 matters in the soil, whether supj)lied in the shape of manure^ 

 or from accumulated vegetable and animal matter in a state 

 of decay. Good farm-yard manure, in a recent state, not 

 too much decayed, will aiford the farmer an abundant sup- 

 ply, and unless these matters are supplied to the soil, the 

 inorganic or mineral elements, such as the alkaline phos- 

 phates and silicates, will not be of much avail to the growth 

 of the crop. Mr. Karkeek then adverted to the doctrine 

 recently introduced by Professor Liebig, which under-esti- 

 mated the influence of organic manures in the soil, and 

 attached the more importance to the inorganic constitu- 

 ents of plants, by keeping a supply of which in the soil 

 lie is of ojunion that the carbon and nitrogen, which are 

 necessary for the growth of the plant, will be supi)lied 

 through the atmosphere. This is a theory altogether op- 



