1018.] SOILS FERTILIZERS. 725 



" Under aerobic conditions Azotobacter in liquid cultures reduced nitrate to 

 nitrite, but not to ammonia. More atmospheric nitrogen was assimilated in the 

 presence of nitrate than in the absence of this salt. 



"Pigmentation occurred when potassium and sodium nitrates, and especially 

 calcium nitrate, were used with Azotobacter, the coloration increasing with the 

 concentration of the salt. This effect was more marked in Azotobacter strains 

 which produce little or no pigment in the absence of nitrates. 



"All three nitrates studied caused an increase in the number and size of 

 volutin bodies in Azotobacter cells. From all appearances these salts also 

 tended to hasten the development of these bodies. 



" The number of B. radicicola in sterilized soil was increased by the addition 

 of small quantities of potassium, sodium, ammonivun, and calcium nitrates. 

 This increase was not so marked as in the Azotobacter cultures. B. radicicola 

 appeared to be much more resistant to higher concentrations of nitrates than 

 Azotobacter. 



"B. radicicola under aerobic conditions did not reduce nitrates in solution to 

 nitrite, ammonia, or elemental nitrogen. The presence of nitrates did not mate- 

 rially influence the small amount of atmospheric nitrogen fixed under these 

 conditions. When grown on agar films, B. radicicola fixed a small amount of 

 nitrogen, varying from 0.15 to 0.43 mg. of nitrogen in 100 ca of the medium. 

 The addition of various amounts of potassium, sodium, and calcium nitrates in- 

 creased to a slight extent the amount of nitrogen assimilated. In liquid cul- 

 tures all three nitrates caused a large increase in the amount of gum obtained 

 by precipitation with acetone. 



" The presence of large amounts of potassium, sodium, and calcium nitrates 

 proved detrimental to the formation of nodules on alfalfa. B. radicicola did 

 not appear to lose its infecting power when grown on media containing varying 

 amounts of sodium and calcium nitrates. Alfalfa seedlings grown in the pres- 

 ence of large amounts of nitrate did not produce nodules when inoculated with 

 a viable culture of B. radicicola. Nitrates in soil cultures prevented the re- 

 formation of nodules once removed and also caused a decrease in the number 

 of nodules already present." 



A list of 49 references to literature cited is given. 



The addition of tar to calcium cyanamid to facilitate spreading, Schmoe- 

 GER and Lucks {Mitt. Deut. Landw. Gesell., No. 10 {1917), pp. 156, 15T; abs. in 

 Internat. Inst. Agr. [Romel, Internat. Rev. Sci. and Pract. Agr., 8 {1911), No. 

 6, pp. 842-84^). — "In experiments carried out at the agricultural station at 

 Danzig (Pru.ssia) to find, if possible, a method to facilitate the spreading of 

 calcium cyanamid, good results were obtained by mixing the manure with 15 

 per cent of coal tar. 



" The cyanamid is first mixed with the tar and then passed through a minc- 

 ing machine. The material thus obtained is rather similar to superphosphate. 

 It may be easily spread without powdering, a characteristic which it does not 

 lose even when kept for a long time. The addition of tar causes no loss of 

 nitrogen. 



" In order to determine whether the addition of tar is harmful to plants 

 fertilized with cyanamid, pot-manuring experiments were cari-ied out with oats 

 durins the summer of 1915. The plants grew equally well in pots treated with 

 cyanamid and tar as in those treated with pure cyanamid or with ammonium 

 sulphate, and much better than in pots without nitrogenous manure. . . . 



" In April, 1916, a .second experiment was begun. This was carried out with 

 ten pots divided into five equal groups treated respectively with the following 

 manures: (1) No manure, (2) pure calcium cyanamid, (3) cyanamid plus 



