Vol. VIII. Xo. 196. 



THE AGEICULTUKAL NEWS. 



343 



USEFUL BACTERIA IN JAMAICA SOILS. 



The bacteria which possess iinporfcarce in connex- 

 ion with their relation to the nitrogen in the soil are, 

 broadly speaking, of five kinds: those which change 

 ammonium salts inr,i) nitrites ; those which convert the 

 nitrites thus (brmed into nitrates; those which take 

 nitrogen from the air and actnally enrich the soil with 

 chat element by adding it in a fixed condition ; those 

 which live in the nodules of leguminous plants and 

 .supply them with nitrcjgen from the air; and finally 

 those wliich break down nitrogen compounds in the 

 soil and return the nitrogen that they contained to the 

 air. The first two are called nitrifying organisms ; they 

 do not add nitrogen to the sod, but render more 

 available that whi(:h it already contains. The third 

 are termed nitrogen-fixing bicteria; the reason for 

 this is evident from whit has been stated. Of the last 

 two, little need be sai<l here except that the former 

 are, of course, beneficial, while the latter are responsible 

 lor the loss of nitrogen from badly kept soils. 



In the Ballcfin of (lie Bi/piirlment of Aijricidtwre, 

 Jamaica, Vol. I, No. 2, the results of an investigation 

 of the nitrifying and nitrogen-fixing bacteria in the 

 soils of Jamaica, which was carried out at the Govern- 

 ment Laboratory there, are given. The following are 

 extracts from the paper: — 



The preceding issue of the Bullutin contained an article 

 describing broadly the relations between the biochemical 

 activity of the more important soil bacteria and the fertility of 

 the land. Special attention was drawn to the ' nitrifying ' and 

 the ' nitrogen-fixing ' bacteria. The writer has recently 

 examined some Jamaican soils for the presence of those two 

 groups of organisms. To test for the ' nitrifying ' bacteria 

 two mineral .solutions were employed, one containing sulphate 

 of ammonia, nutritive salts and carbonate of lime, and the 

 other nitrite of sodium together with nutritive salts. 



To prove the presence of ' nitrogen-fixing ' bacteria, 

 a solution of sugar (or the closely allied mannite) was used, 

 together with nutritive salts and carbonate of lime, but no 

 combined nitrcigen in any form. These liquids were rendered 

 sterile by heating in steam. The moist samples of the 

 different soils were partly dried, broken down into a fine 

 condition, well mixed, and 1 gramme (about 15 grains) of each 

 introduced into the three culture solutions, which were then 

 put in a dark place at air temperature. 



The three soils tested were ; — 



1. A soil at Hope Gardens cleared of bush during the 

 last year and planted with Guinea grass. 



2. A rather stiff soil from a citrus fruit plantation at 

 Hartlands. 



3. A Westmoreland .sugar-cane soil at the foot of 

 a range of limestone hills. 



These soils had all a neutral reaction to litmus. The 

 Hope soil set up ' nitrification ' of the ammonia and the 

 nitrite, only after a long interval, and the characteristic 

 ' nitvogen-Hxing' A -.otoliacter appeared in the sugar solution 

 also at a late date. 



The phenomena were brought about by the Hartlands 

 soil much sooner, while the Westmoreland .soil acted still 

 more promptly. 



The earlier ' nitrification ' and ' nitrogen-fixation ' begin, 

 the more numerous and the more artive are the respective 

 bacteria in the soil. In the Hope soil, the bacteria were 

 scanty in numbers and sluggish in action, whereas in the 



other two soils they wore numerous and active, especially ia 

 the Westmoreland .soil. The differences shown stand in clear 

 connexion with the amount of calcium carbonate present in 

 the respective soils. The Hope soil was very deficient in the 

 base carbonate of lime, whereas the relatively small amount 

 present in the Hartlands soils was eaough to secure a healthy 

 multiplicatitni and activity of both groups of bacteria. 

 Ghemical analysis of the Aiotobacter cultures from the 

 Hartlands and Westmoreland soils, after the .sugar had all 

 been oxidized by the bacterium, showed in both cases that 

 9 parts of nitrogen had been gathered from the air for 

 every 1,000 parts of sugar destroyed. Some of the sugar 

 solutions (containing glucose) inoculated with the Hope soil 

 yieUed no A zofo/Micter, hat gSLve rise to a long continued 

 butyric fermentation due to spores forming sjiecies of 

 Clostridia. Analyses of these showed that only g-part of 

 nitrogen had been gathered from the air for every 1,U00 parts 

 of sugar decomposed. Where, therefore, soil conditions are 

 unfavourable for the abundant growth of the A-otobacter, 

 owing to the deficiency of carbonate of lime, the nitrogen- 

 gatherhig power of the soil is greatly weakened, since the 

 Clostridia are only (nie-third as efficient workers as the 

 Azotohacter. 



JAMAICA RUM. 



A piper in the Iriternational Sugar Journal, 

 Vol. II, No. 129, gives the results of an investigation of 

 Jamaica rum which w.as conducted by Dr. Karl Micko, 

 Director of the Public Research Institute for Food- 

 stuffs, Graz. The conclusions reached are as follows: — 



1. Jamaica rum contains an aromatic constituent 

 peculiar to it alone, which is the basis of its characteristic 

 flavour. This constituent is found neither in high class 

 European spirits nor in artificial rum. 



2. This typical flavouring body of .Jamaica rum is a col- 

 ourless, notdiflicultly volatile, fluidof a delicate aromatic smell, 

 and its boiling point lies higher than that of ethyl alcohol. 



3. This typical body belongs neither to the esters, 

 ketones, or aldehydes. It has the general cliaracteristics of 

 an ethereal oil, and it is not improbable that it stands in 

 nearer relation to the terpenes. 



i. The typical flavouring body does not dissolve in 

 caustic soda ; but on prolonged contact with it, it assumes 

 an aromatic, but more resinous, smell. 



5. In Jamaica rum, as in other high class spirits, is 

 a body possessing a terpene-like aroma which is entirely 

 absent from artificial rum. But it is less characteristically 

 a proof of .Tamaica rum, as in other high class spirits similar 

 bodies, rich in terpenes, are found. 



6. In Jamaica rum, there occurs in the last distillation 

 fraction an aromatic-smelliug, resinous substance, which 

 dissolves in caustic soda and is precipitated by the addition 

 of acids. It is questionable whether this substance is 

 a primary fermentation product, for we can produce such 

 substances easily from aldehydes. 



7. The analyst with sensitive nose and palate can easily 

 distinguish artificial, from Jamaica, rum. He is also in the 

 position to be able to detect mixtures of Jamaica with 

 artificial rum. 



8. From chemical analysis alone, however, no thorough 

 conclusion is possible, but when used in conjunction with the 

 smelling test, it is extremely valuable. The ester number is 

 of especial value for determining whether the given sample is 

 of a concentrated or a diluted rum. 



