Scientific Agriculture. 



154 



[August, 1909. 



evident, and the existence of a prac- 

 tically unlimited amount of nitrogen in 

 the atmosphere has fired the imagination 

 of scientific men and stimulated per- 

 sistent research into the question of the 

 conversion of the free nitrogen of the 

 air from its inert gaseous condition to a 

 combined state suited to the needs of 

 all crops, 



The efforts to utilise this constituent 

 of the atmosphere for the production of 

 a nitrogenous plant-food on an econo- 

 mical scale have been crowned with 

 success during the last three or four 

 years, and at the present moment two 

 new fertilizers are being placed on the 

 market. One of them, calcium cyana- 

 mide, introduced under the trade name 

 of "Nitroliu" is obtained by heating the 

 pure nitrogen of the air with calcium 

 carbide (the well-known material used 

 in bicycle lamps) in an electric furnace ; 

 the nitrogen is absorbed by the carbide, 

 and calcium cyanamide is produced. It 

 is a fine powder, somewhat like basic 

 slag, containing 20 percent, of combined 

 nitrogen, an amount equal to that in the 

 best samples of sulphate of ammonia. 

 It contains also a certain amount of lime, 

 which is of benefit upon soils deficient 

 in that material. In comparative trials 

 with sulphate of ammonia and nitrate of 

 soda upon Potatoes, Cabbages, Wheat, 

 Mangels, as well as many garden crops, 

 it has proved itself an excellent substi- 

 tute for these manures. Since it is 

 liable to check germination and damage 

 seedling plants, it is best applied to 

 the land 10 to 14 days before sowing 

 9eeds. The application may be made 

 at the rate of 1 cwt, to 2 cwt. per 

 acre, and when intended for use as 

 a top-dressing it should be mixed 

 10 to 14 days before application with one 

 to four times its weight of finely-divided 

 soil- Like sulphate of ammonia, it does 

 not act immediately upon crops, but 

 must first be nutrofied or changed into a 

 nitrate in the soil. It is adapted for use 

 in all kinds of land, with the exception 

 of those of an acid character or on light 

 sands where the nitrifying bacteria are 

 are not abundant. 



The other product whose nitrogen is 

 obtained from the air is calcium nitrate, 

 a compound which is certain to become 

 a formidable rival of all nitrogenous 

 fertilizers, and, with "Nitrolin," is 

 destined to have a far-reaching effect on 

 the production of the world's crops. As 

 far back as 1786 Cavendish discovered 

 that the combination of the nitrogen and 

 oxygen of the air can be brought about 

 by the passage through it of an electric 

 spark. This fact has never been lost 

 sight of by chemists and engineers, but 



its practical and ecouomic application 

 have not been attained until recently. 

 Several methods of bringing about this 

 chemical combination on a large scale 

 are now known, but the process which 

 is apparently giving the best results is 

 that devised by Birkeland and Eyde 

 in Norway. The union of the gases 

 occurs in a specially-constructed electric 

 furnace, the oxides of nitrogen being 

 afterwards passed into water, and the 

 nitric acid formed subsequently com- 

 bined with limestone. The nitrate of 

 lime pioduced is sent into commerce 

 75-77 per cent, pure and containing 13 

 per cent, of nitrogen — about 2 per cent, 

 less than in nitrate of soda. It is a 

 brownish substance without smell, very 

 soluble in water and as active as nitrate 

 of soda upon plant growth. Experi- 

 ments both in this country and abroad 

 have shown that its nitrogen is quite 

 as efficient, unit for unit, as that in the 

 latter manure, and on soils deficient in 

 lime it is likely to be more effective. 



The prophetic statement by Sir 

 William Crookes that starvation may be 

 averted through the laboratory, and his 

 suggestion, that the production of elec- 

 tricity at a cost sufficiently low to make 

 the manufacture of nitrates from the 

 air a commercial success may be attained 

 through the utilisation of water power, 

 are now being realised. Thedangerofa 

 nitrogen famine and its consequent 

 bearing upon the growth of human 

 food cereals has been removed by these 

 new achievements of the chemist and 

 engineer. 



The first factory for the manufacture 

 of calcium cyanamide was erected at 

 Piano d'Orte in Italy, but others have 

 been established in Austria, Germany 

 and France. The North- Western Cyana- 

 mide Co.'s works are situated at Odda, 

 near the southern end of the Hardauger 

 Fjord in Norway, and from this centre 

 the new fertiliser will be supplied to the 

 United Kingdom and its colonies and the 

 greater part of north-western Europe. 



Nitrate of lime is manufactured by 

 the Norwegian Hydro-Electric Co. at 

 Notodden, in Telemarken, the energy 

 for the electrical power being obtained 

 from a neighbouring waterfall. The 

 output of the factory is at present about 

 20,000 tons per annum, but in less than 

 two years, when a new factory will be 

 in working order, with power derived 

 from the Rjukan Falls — the largest in 

 the country— the production will be 

 increased to 100,000 tons per annum. 



The question of cost will largely deter- 

 mine the use to which the new ferti- 

 lisers will be put. The unit of nitrogen 



