306 



THE AGKICULTURAL NEWS. 



October 1, 1910. 



to be done before sufficient is known about its applica- 

 tion and practice to decide upon its economic value. 



Where plants are being grown under glass, on 

 an intensive scale, the plan is feasible of employing 

 radio-culture in conjunction with the means that has 

 just been descibed, namely the induction uf an 

 electric current in the soil. An actual system, known 

 as the Thwaitc System of Electro-Culture is under 

 trial at the Royal Botanic Gardens, Kew. In this, 

 violet light is projected on to the plants from powerful 

 lamps that may be arranged to send their rays in any 

 direction; at the name time, an electric current is sent 

 through the atmosphere and induced in the soil in the 

 way described above. The plants have, naturally, to be 

 provided with the proper amount of carbon dioxide and 

 water, and the stimulus to their growth entails the 

 insurance of a .sufficient quantity of food in the soil by 

 the use of suitable artificial manures. The dynamo pro- 

 ducing the electricity is run by means of a suction gas 

 plant, which also provides the power for driving an elec- 

 tric machine which yields the electricity for the atmos- 

 phere and the soil. Excellent results have been obtain- 

 ed under this system, the ordinary working expenses of 

 which are said to be i-emarkably low 



Other methods employing the more direct applica- 

 tion of electricity to the plant and its environment 

 include the utilization of the electricity present in the 

 atmosphere, and the electrification of seed immediately 

 before it is sown. In the first case, a kind of lightning 

 c<jnductor is erected in the field, and a network of 

 wires running through the soil is connected with this, 

 so that any exchange of electricity between the con- 

 ductor and the atincsphere causes currents to arise in 

 the wires that are in the soil. For the trials that have 

 been made in the electrification of seed intended to be 

 sown, the current used was such as may be obtain- 

 ed &-om an (jrdinary medical battery. In the employ- 

 ment of both (if these methods, increased yields have 

 been obtained; though they have not met with any 

 extended application, as yet. 



The application of electricity for agricultural pur- 

 poses in less direct ways, such as that of the provision of 

 energy for transport and for the carrying out of field 

 operations, is being rapidly extended. The electric 

 railway, the electric plough and the electric motor are 

 bound to take an increasingly greater part in agricul- 

 tural operations, in the future. The last of these is 

 especially useful, as it can be made to provide a source 

 of energy for driving all kinds of stationary machinery 

 on a farm or estate. The efficiency, cleanliness and 

 easy manipulation of such motors cannot fail to bring 



them eventually to a position of the greatest import- 

 ance in relation to agricultural work. 



Among the minor uses of electricity on farms and 

 on estates are its employment in dairies and for driving 

 machines used in the household work. More particul- 

 arly in this relation, the existence of the telephone 

 must not be forgotten; the utility of this instrument is 

 being found especially great in the United States, 

 notably with regard to the transmission of weather 

 forecasts and storm warnings. 



The consideration of the most important indirect 

 applications of electricity to the uses of plants has been 

 left to the last. These consist in the manufacture of 

 nitrogenous manures in which the nitrogen has been 

 obtained from the atmosphere. The most important of 

 such substances as is well known, are nitrate of lime, or 

 nitrogen lime, and calcium cyanamide, ornitrolim. The 

 necessity for the manufacture of such substances was 

 most plainly indicated, first, in a presidential address 

 delivered a few" years ago by Sir William Crookes before 

 the British Association. The circumstances of ihis are 

 familiar. Attention was drawn to the large waste of 

 the nitrogen that was once in the soil, which is taking 

 ])lace through the methods in vogue for the disposal of 

 animal refuse. It was evident that this animal refuse 

 was originally in the form of plants, and that the.se 

 plants had been enabled to grow because they could get 

 nitrogen from the soil. It required little thought, there- 

 fore, to show that, unless some means was found to return 

 this nitrogen to the soil, under conditions in which it 

 would become available as plant food, or at any rate to 

 replace the nitrogen in the soil by some inexpensive 

 means, there was great danger that the supply of this 

 valuable element would eventually decrease to such an 

 extent as to <liminish seriously the general rate of agri- 

 cultural production. The iiiinufacture of the manures 

 mentioned has become a coinuiereial possibility, owing 

 to the recognition of these facts, anfl of the circumstances 

 that such natural stores of available nitrogen as the 

 nitrate beds <jf Chili must eventually become exhausted. 



There is no need, here, to enter into details as 

 to the manufacture of the substances mentioned — - 

 nitrate of lime and calcium cyanamide; it may be 

 stated that the first process is described in the 

 Agricultural News, Vol. VIII, ji. 82.5, while the 

 production of calcium cyanamide is dealt with in 

 Vol. VII, p. 39y. It will be sufficient to indicate the 

 way in which electricity is used in making them. In 

 the first case, it is employed to produce the highly heated 

 space (or 'flame') which ciiuses the oxygen and nitrogen 



