Vol. XIi. Xo. 282 



THE AGRICULTURAL XI-.W?. 



A New Method of So:l Analysis. 



It has already been shown by Dumont in France 

 that sindy particles extracted in thr course of an 

 ordinary mechanical analysis of the soil are coated with 

 M layer of clay-humus, and in compact soils, where 

 colloidal elements abound, the presence of these coat- 

 ings may falsify analytical results. In the Bulktin 

 of the Bureau of Agricultural Intelligence and of 

 Plant Diseases for January 1912, an account is given 

 of Dumoni's ingenious method of breaking up these 

 clay-hiuiiiis coatings with oxalic acid and of his method 

 of separating silt and clay by centrifugalization. 



The operations may be brieriy described as follows: 

 II 1 ) treatment of the fine earth with oxalic acid, deter- 

 mining at the same time the peicentage of carbonates 

 from the carbon dioxide evolved: (2) dissolution of the 

 humus substances with ammonia, and separation of 

 the sands by the ordinary method of sedimentation; 

 ; -S) separation of silt and rine silt by centrifugalization, 

 ! 1,000 revolutions per minute for a (piarter of an hour): 

 (4.) coagulation of the clayey and colloidal elements by 

 amniDniiim carbonate separated together from the 

 Jiquid by centrifugalization; (-5) determination of the 

 humus by evaporation of the remaining liquid in which 

 the ash is also determined by igniting the residue. 



Apart from its extreme accnrac}', a great advan- 

 tage of the method described above lies in the fact that 

 the entire analysis can be completed in half a day. 



Nitrogen-fixing Bacteria in Leaves. 



An abstract of a preliminary report of investi- 

 gations b}' F. C. von Faber on bacteria in the 

 leaves of Rubiaceae (a family of plants containing, 

 nmong others, coffee, Ixora, Gardenia and Cinchona), 

 is contained in the Ex'periment Station Record, 

 Vol. XXVII, No. 3. It is stated that plants of 

 this group bearing these bacteria may be detected 

 hj peculiar knotty thickenings of the leaves. Garden 

 plants so affected are several species of Pavetta and 

 I'sycliutria liacteriophila. Bacteria are found in the 

 growing points and from there supposeilly extend with 

 the growth of the plant. The chief mode of infection 

 however appears to be by means of the stomata in the 

 young bud leaves, resulting in the formation of a char- 

 acteristic bacterial tissue which manifests itself to the 

 naked eye as knotty thickenings. Starch grains have 

 been found in this tissue and are supposed ti^' serve 

 initritive purposes for the bacteria. Already pure 

 cultures have been obtained from Paretta indica and 

 Psycliotria hactcriopldla. They appear to be biological 

 strains of the same species. The author states that 

 experimental evidence has been obtained which sup- 

 ports his hypothesis that these bacteria are symbiotic 

 nitrogen-tixing organisms. 



It will be rembered that a few years ago Professor 

 Bottomley discovered bacteria in the cortical cells of 

 the tomato plant; and although they were not appar- 

 ently pathogenic, it was never established that they 

 ivere able to fix atmospheric nitrogen. 



Agriculture in Southern Nigeria. 



Excluding products of the oil palm, which is no% 

 systematically cultivated, the most important crtps' 

 grown for export in Southern Nigeria are cacao, cot to u, 

 ground nut.benniswd (or sesame) and maize. Para rubber 

 is being extensively cultivated in certain districts. This 

 information is taken fr^m Colonial Reports — Annual, 

 No. 735, for Southern Nigeria (1911), in which statLs- 

 tics are also given showing the amount of cacao ai. J 

 cotton exported during the past five years. In 1907, 

 2,089,225 H). of cacao valued at £47,840 was shipped. 

 This has steadily increased until 1911, when 

 9,858,774 ft. of cacao were exported from the Protec-- 

 torate, valued at £iG4,6(J4. The quantity of cotton 

 products exported has been subject to considerable-'' 

 fluctuation, but the average annual output for the lasb 

 iive years has been 28,810 cwt. of cotton lint valued 

 at £79,808, and 3,207 tons of cotton seed, valued at" 

 £7,(i90. 



Reference should be made to the tapping expeil- 

 ments on rubber trees; and in this connexion, as well as 

 in the exploitation of cotton, palm oil, tanning materials 

 and minerals, work conducted at the Imperial Institute 

 has greatly aided in general development and progress. 

 ^^^^^►-♦-^^— 



A New Weed Exterminator. 



Wild garlic {Allium vinale) has for many ycare 

 been a serious pest in that belt of territory which 

 extends from Maryland to Missouri. Besides having the 

 usual competitive action of a, perennating weed, the 

 plant is harmful in tbgi the bulbils on the stern 

 frequently get intermixed with wheat grain and create 

 an objectionable flavour in the Hour. As a weed with 

 fodder crops, this plant may have an effect in causing 

 the tainting of milk. 



Considerable attention, therefore, has been directed 

 by the Botanical Department of the Indiana Hx])oriment 

 Station, towanls methods for eradicating this noxious 

 weed. A letter in Science, for January 8, 19 1-'!, states 

 that remarkable results have been obtained by the use 

 of orchard-heating oil as supplied by the Standard Oil 

 Company. It was found that when the oil was 

 distributed over the field in a fine spray by a sufficiently 

 powerful spraying machine, practically all vegetatioa 

 was killed, not only above ground but below ground as 

 well. It destroyed the bulbs of the wild garlic below 

 ground and the bulbils at the top of the stalks. ()jie 

 or two plants with very large horizontal rootst(io):s 

 survived, since these required a rather larger dose of 

 oil than was generall}' applied. 



The application of the oil appeared to have iia 

 lasting effects on the soil: the new growth from sicfe 

 already present in the soil and from subsequently sowa 

 cereals possessed the usual vigour. 



In considering the trial of this method in the 

 West Indies for exterminating perennial weeds like 

 Devil's grass {Cipiodon Dactylon) and Nut grass 

 (Gi/perus sp.) the following questions arise: (1) Will the 

 oil actually kill the hardy rhizomes and tubers of these 

 weeds? (2) Does the oil possess any injurious ert'ecS 

 regarding the ))hysical and biological characters of the. 

 soil' And: (3) What would be the cost per .acre.' 



