THE GARDENERS' CHRONICLE OF AMERICA. 



715 



FERTILITY FROM THE AIR. 



By F. H. Mason. 



While foinierly we had to rely on animal excrement, 

 amniunia l)y-products made in the manufacture of 

 lighting gas, and the vast deposits of sodium nitrate, at 

 Chili, to provide nitrogen fur our crops, to-day \vc are 

 exploiting the practically unlimited supply of nitro- 

 gen in the atmosphere for that purpose. 



Though the existence of this enormous body of nitro- 

 gen has been known since 1772, when it was discov- 

 ered almost simultaneously by Rutherford, Priestle}-, 

 and Scheele, it is only of recent years that man has 

 been able to apply it practically to agricultural pur- 

 poses. Two methods are in use to bring this nitrogen 

 into a condition available for plant life. The one is an 

 electro-chemical method, in which the vast water pow- 

 ers of northern Europe are employed to provide elec- 

 tricity, which, under certain conditions, causes the 

 nitrogen and oxygen of the atmosphere to unite, and 

 the resulting nitric acid is fixed in lime, forming nitrate 

 of lime, in which state the nitrogen is applied to the 

 soil. The second, and perhaps the more interesting 

 method, is that of bringing into service certain bac- 

 teria that exist in the soil, and which have power, under 

 favorable conditions, of conveying nitrogen from the 

 atmosphere to the soil in a form available to plant life. 

 Though this latter method is in its infancy, it already 

 gives considerable promise to be the cheapest effective 

 method of providing plant life with nitrogen. The 

 conditions that have been fuund nxost favorable for the 

 activities of the "Azotobacter" — the chief nitrogen- 

 fixing bacterium — are a soil well charged with decay- 

 ing vegetable matter, one containing about eighteen per 

 cent, of moisture, one that is open and well cultivated, 

 and, last, one containing lime or other alkali, in which 

 the nitrogen from the air can be fixed. Certain crops, 

 loo, particularly the members of the pulse family, fa- 

 cilitate the operations of the bacteria. 



There is, however, by this latter method, a danger 

 of getting too much nitrogen in the soil, and this has 

 actually been done in parts of Colorado. There the 

 soil often contains a large amount of alkali, which 

 seems to have made it particularly suitable for the 

 operations of the "Azotobacter"; the irrigation appears 

 to have provided the required amount of moisture and 

 cultivation — turning under vegetable matter — the 

 needed humus. In jjarts df Colorado so much nitrate 

 of sodium has been formed l)y the "Azotobacter," and 

 so virulent has been the excess of this salt, that 

 orchards which have been in bearing for twenty-five 

 years have been destroyed in a single year. 



We are learning to conirol the ".Azotobacter," how- 

 ever, and there seems to be every reason to hope that 

 by its aid the crops f)f the future will be provided with 

 cheaj) nitrogen. 



A CUNNING HAND AMONG THE 

 BRANCHES. 



The follow ing nntes cm tlu- bifin'catii >n .-ind bi'aiiching 

 of trees, copied from Chambers' Journal, \'(il. \'ll., 

 January to June, 18.S7, ha\e been sent us by a reader: 

 "Did you ever notice thai sometimes two branches of 

 a tree produce a perfect i)ifnrcation ; that is, that they 

 separate from a common pnint? If you examine closelv 

 you will find that such branches took their departure 

 from one and the same hud. In rarer instances, you 

 may see five or si.x branches all starting from a com- 

 mon center, and with a regularity that surprises wlien 

 contrasted with the arrangement of the rest of the tree. 



These eflfccts are now and then produced by gemming 

 or inoculating, and not seldom by the unassisted handi- 

 work of Nature. When the latter is the case, the bifur- 

 cation is caused by the bite of a caterpillar or some 

 other voracious insect. An insect has but to gnaw the 

 point of a bud to make it grow double, triple, quad- 

 ruple, and so forth, to transform itself, indeed, into nu- 

 merous buds, thereafter distinct and separate, each 

 passing singly through all the phases of its vegetation. 

 What is here said applies to buds that produce wood ; 

 it is equally true of those that produce fruit. The in- 

 sect plies its mandibles and quite unconsciously starts 

 a new order of developments. After all, however, a 

 little reflection would lead us to believe that buds might 

 be as fecund as seeds. If one grain of wheat produces 

 many grains, why not one bud many buds, if we can 

 only get it into the right condition? What this condi- 

 tion is we learn from the insect. .\t all events, it has 

 been learned by M. Millot-Brule of Rethel (Ardennes), 

 and turned to good account, for he produces eft'ects at 

 pleasure without waiting for the accident of an insect: 

 With the point of a penknife or a slip of sandpaper he 

 makes buds produce as many branches as he chooses. 

 The notion occurred to him in 1840, and he at once 

 made experiments which were successful ; and, repeat- 

 ing these year by year, he has now produed a new and 

 similarly interesting process of arboriculture. A com- 

 mission appointed by the Minister of Agriculture and 

 Public Works to examine into it reported in the fol- 

 lowing terms of what they had seen in M. Millot-Brule's 

 gardens : Several peach stems present a multitude of 

 branches proceeding from the same center with math- 

 ematical regularity and symmetry. By skilful disbud- 

 ding, by incisions, and nipping of the buds or shoots, 

 he arranges the trees in a way at once the most pic- 

 turesque and fantastic. Under his fingers the obedi- 

 ent branches assume the most varied and elegant 

 forms ; he increases the fructification, and develops the 

 formation of buds according to his wish. Thoroughly 

 to illustrate the results, diagrams would be necessary. 

 We shall, however, endeavor to explain as clearly as 

 the subject will admit of. M. Alillot-Brule's elementary 

 figure consists of a straight branch which from one 

 common center separates into fifteen branches, resem- 

 bling, in fact, a small tree with a regularly formed head. 

 A second represents an espalier peach tree, the 

 branches of which radiate in the form of a wheel, each 

 branch terminating in an oval ring of smaller branches, 

 developed at regular intervals. From these simple 

 forms others of a more coniple.x nature may be pro- 

 duced: A single stem, properly managed, will form a 

 square, a parallelogram, or a series of circles so elegant 

 in design that if copied in ])a]Mer-mache they would l)e 

 prized as graceful ornaments for the drawiiig-room. 

 The buds may bfe multiplied and the branches sent oiT 

 entirely at the pleasiu-e of the cultivator. Hence there 

 is no limit to the forms which may be produced. In 

 the course of his experiments he discovered one of the 

 int^eresting secrets of arboriculture — namely, that little 

 branches must not be developed immediately opposite 

 each other on a horizontal branch trained against a 

 wall, or on stakes: and the reason is that the branches 

 which run upward take up all the sap at the expense of 

 those running downward; the latter, consequently, lan- 

 guish. It therefore becomes absolutely necessary to 

 develop the small liranches alternately — each lower one 

 between two upper ones — on all horizontal branches. 

 It is possible, mureox er, to assist the lower branches by 

 bending the upper ones upon themselves, making them 

 form a sort of knot, but always with the precaution of 

 leaving the extreme jtoints in an upward direction. 



