Vol. VII. Xo. 157. 



THE AGIUCULTURAL NEWS. 



1.35 



ATMOSPHERIC NITROGEN AND ITS 



FIXATION BY ELECTRICAL METHODS. 



The question of how to provide a continuous and 

 avaiUible supply ot nitrogen to growing crops at the 

 least cost is discussed in an article, ' The Present Status 

 of the Nitrogen Problem,' that appears in the latest 

 issue (190(3) of the Yearhool- of the United States 

 Department of Agriculture. The writer concludes that 

 in the case of the greater propoition of the available 

 land of the world this question will become a problem 

 of bacteriology, with the soil as a culture medium. 

 But while much can be accomplished through the 

 agency of soil bacteria in conserving and increasing the 

 supply of combined nitrogen, it is obvious that there 

 will always be a demand for an immediately available 

 supply of nitrates, or other form in which nitrogen can 

 be supplied for the use of growing crops. Since the 

 Chile deposits of nitrate of soda, which for 3'ears past 

 have formed the chief source of supply of this valuable 

 nitrogenous manure, must sooner or later be e.xhausted, 

 it is satisfactory to note that considerable progress has 

 been made of late years in ele<'trical processes designed 

 to effect the fi.xation of atmospheric nitrogen in a suit- 

 able form, so as to make it available for inanurin.l 

 purposes. The following mention of these processes is 

 made in the article in (piestion: — 



It has long been known that Htnios|.)heiic nitrogen can 

 be oxidizeil under the influence of electricity, proihu-ing nitric 

 oxide funle^s, wliich are then combined with water, to t'oini 

 nitric acid, or with quicklime, forming calcium nitrate. Other 

 bases may also be used. Variou.s attempts have been made 

 from tiirie to time to develop a proces.s by which nitrogen can 

 be combined conuiiercially. The most piomising results ha\c 

 thus far been secured w'ith Franck's process of making calcium 

 cyanamidc and with the Kiikland and Kydc process of 

 producing nitrates. The former process consi.sts in combining 

 nitrogen with the rarbides of alkalis, producing cyanides, 

 or, in the case of calcium, producing calcium cyanamidc, 

 containing -35 per cent, of nitrogen — more than twice the 

 amount ^jresont in nitrate of soda The calcium cyanamide, 

 when jjropcrly used, has proved to bean excellent nitrogenous 



fertilizer for many crops, and quite equal to am ia 



compounds, into which it can he readily converted, 'flie 

 ammonia thus produced can be oxidized hy conductin'< 

 ■it over highly heated metallic oxides, producing nitric acid. 



Tne Birkland and Eyde process, liowever, appeals to be 

 the most promising as a means of producing nitrates. 

 A special electric furnace is used, in whjeh an alternating 

 electric are of between 3,000 and 4,000 volts, is produced 

 in connexion with a large electro-magnet, which forces it to 

 take the form of a roaring disc of flame. Air is forced throngli 

 this furnace at the rate of about 3,000 cubic feet per min- 

 ute, the niti'ogen being oxidized in the furnace to nitric oxide. 

 The.se fumes are then collected, and after further oxidation 

 are absorbed i\i water lowers, forming nitric acid, oi- by 

 powdered (piicklime, forming calcium nitrate, ■ Of C(jurse, the 

 nitric acid can be combined with almost anj^' desirable base, 

 .such as soda or potash. 



These direct processes of securing nitrogen will certaiuh 

 be rapidly imiiroved, and what has been acconqilished already 

 in this diiection .should remove the last vestige of doubt that 

 we shall be able to secure at a reasonable, cost all of the 

 inunediately available nitrogen we may need, in addition to 

 the great siqiply that may be .secured thiough bacterial action 



POTASH AS A PLANT FOOD. 



The following notes on the importance of jjotassium 

 as a plant food are taken from an article, 'The Relation 

 oi Nutrition to the Health of Plants,' which appeared 

 in the Yearbook oi the United States Department of 

 Agriculture for 1901 : — 



Potassium, the es.sential ingredient of potash, is well 

 known to be one of the most important and indispensable of 

 all plant foo<ls. Large ijuantities of it are recpiired by all 

 crops. A considerable part of the ash of most plants 

 consists of this material, and though clo.sely related to 

 sodium in its chemical projicrtics, the latter cannot replace 

 it in the plant. Plants growing in .soil which contains more 

 sodium than potassium will nevertheless absorb much 

 more of the potash. One of the first .signs of a lack 

 of potash is a decided cessation- in growth without other 

 apparent cause of trouble. The plants often have their 

 normal green colour, but make very little starch or .sugar, and 

 almost no [a-otein or nitrogenous matter. Pota.sh plays an 

 important part in the formation of starches and sugars, but 

 its greatest importance is in connexion with protein forma- 

 tion, in which it is ajiparently indispensable. When it is 

 remembci-ed that proteins or the related nitrogenous com- 

 pounds arc the main .source of food for the young growing 

 cells, the importance of potassium will be appreciated. 



A ready supply of potassium al.so hastens and perfects 

 the maturing of plants, especially the ripening of the wood of 

 fruit and other trees. A lack of potash is said by Webber to 

 cause in the orange an excessive growth of weak, immature 

 wood. The same writer also calls attention to the fact that 

 many growers believe that potash,acleastintheformofsulphate, 

 causes the production of excessively sour fruit. It would be 

 inqiortant to determine if this is really true. There are good 

 jihysiological reasons which lead us to expect such a result, 

 not only in the orange, but in ]jlants in general. However, 

 an increase of starch (ir sugar would also be expected at the 

 same time. The acid juices of plants are, as a rule, di.sliked 

 by insects and fungi. This may explain why muriate of 

 p(jtash prevents, to some extent, the ravages of the rust mite 

 on the oi-ange, and the injurious action of the rust mite on 

 cottrm. 



C'laj- soils, especially clay loam.s, usually contain from 

 Oo to 0-8 per cent, of potash, lighter loams about 0-3 per 

 cent., and dee[i .sandy soils less than O'l per cent.; but even 

 this small auKaint is equivalent to 3,500 lb. to the acre, 

 a.ssuming that an acre of lanil 1 foot deep weighs 3,500,000 lb. 

 As a rule, therefore, it is only upon the lighter sandy 

 soils that a lack of potash may be expected. In the use 

 of potassic fertilizers careful attention should be given to 

 their comiiosition. iluriate, or chloride of potash, and the 

 sulphate are examples of common potash fertilizers in use. 

 The former is as a rule cheaper, and, for some crops, just as 

 good as the sulphate, and should therefore in these cases be 

 used. The sulphate is preferable for certain crops, and when 

 donbt exist.s, is much .safer and more satisfactory. This is 

 especially true in the case of tobacco, which requires a pro- 

 portion in the leaf of about 6 parts of jiotash to 1 part of 

 chha-ine to be of good burning (piality. Night soil, kainit, 

 and other manures rich in chlorine should not be used for 

 tobacco. 



Wood ashes contain a great deal of potash, but 

 practically the whole amount used for raanurial 

 purposes is obtained from the mines at Stassfurt, 

 Germany, which appear to be almost inexhaustible. 

 The priee of this fertilizing constituent has remained 

 practically constant during the past fifty years. 



