120 EXPERIMENT STATION RECORD. 



The activity of bacteria in soils, V. Bromberg (Illus. Landrv. Ztg., 21 

 {1907). pp. m, J78; abs. in CJiem. Ah.^.. 1 (1907). No. 10, p. 1309).— The 

 dependence of nitrogen-fixing bacteria upon the organic matter of the soil is 

 discussed. 



Assuming that 1.000 gm. of organic matter is used by Itacteria in fixing 8 gm. 

 nitrogen, it is estimated that on a soil containing 2 per cent humus the organ- 

 isms would produce 42 lbs. nitrogen per acre per year. Increasing the amount 

 of organic material or source of energy' in the soil by the addition of humus- 

 forming substances and by cultivation, or by favoring the grovs^th of algaj, tends 

 to i-aise the nitrogen-accumulating power of the soil. Fallow favors bacterial 

 action most. Plats inoculated with nitrogen-fixing organisms produced 18 to 56 

 per cent more dry matter and 23 to 130 per cent more nitrogen than uuinocu- 

 lated plats in the case of soy beans, lupines, and seradella. 



Further experiments on nitrogen-fixing bacteria, Keding (TF/.ss, Meere- 

 simter.s. AM. Kiel. 9, p. 27J; abs. in Centbl. Bakt. [etc.]. 2. Abt.. 18 (1907). 

 No. 10-12, pp. 351-353). — The author reviews work of other investigators and 

 reports experiments of his own on the nitrogen-fixing bacteria found in sea 

 v,-ater and in soils of various kinds. He confirms the conclusion of Keutner 

 that Azotobacter occurring in sea water is. in all respects, similar to that found 

 in soils. Sodium chlorid was found to favor the growth of this organism. 



The organism was found in all soil saui])les examined except those from moor 

 lauds. Its fixing power was not affected eitlier by the air drying of soil in 

 which it occurred during 11 months or by rapid drying over sulpluiric acid. 

 The organism was capable of assimilating the nitrogen of the air in pure 

 cultures. This power was not increased by associative action of other bacteria 

 and the nitrogen compounds of the air were also without influence. 



The use of nitrobacteria in Mexican agriculture, C. Macias (BoI. Sec. 

 Fomento [.l/c.//co1, 6 (1906), Nos. J,, pp. T-'z-T.-^,"; 6', pp. 2:u-263, ph. 3; 7, pp. 

 267-27-); 8, pp. 291-309). — This is a preliminary report on investigations made 

 under the auspices of a special commission on agricultural parasitology, ap- 

 pointed by the Mexican government to study especially the root tubercle organ- 

 isms of leguminous plants. The report, however, summarizes information 

 regarding all of the more important organisms which are known to fix and 

 transform nitrogen in the soil, as well as those assimilating nitrogen of the air 

 in symbiosis with leguminous plants. 



Informaticni regarding the preparation and use of efficient, nitragin cultures 

 is given with considerable fullness, the general conclusion being reached that 

 inoculation with this material is not applicable to all soils, but that the indi- 

 vidual soil conditions nnist be studied and that in any case only the more viru- 

 lent organisms should be used. 



The inoculation question in soil bacteriology, P. Ehrenberg (Fiihlinr/'s 

 Landiv. Ztg., 56 (1907). Xo. 9. pp. 301-311).— The progress of investigation on 

 this subject is briefly reviewed, special attention being given to the relative 

 merits of soil and seed inoculation. The conclusion is reached that notwith- 

 standing some disadvantages in its present stage of development, seed inocula- 

 tion is a s:itisfac-t.ory, cheap, and convenient method when carried out with 

 proper precautions. 



Fertilizers, E. B. Ferris (Mississippi Sta. Bui. 99, pp. 16. flf/s. 3).— This bul- 

 letin summarizes the results of 5 years' experiments with fertilizers, manures, 

 and restorative crops on fruits, vegetables, and staple farm crops at the McNeill 

 substation, which is situated on sandy and sandy loam soil " similar to those 

 which occur throughout the long leaf pine belt, which occupies an area of some 

 15,000 s(iuare miles, or practically one-third of the entire State." 



