SOILS FERTILIZERS. 949 



source of nitrogen. At least, the action of the firsl is in no way inferiorto thai of 

 the second. Beets are much more responsive to applications of nitrate than ammonia 

 nitrogen, and their growth is especially promoted by applications of nitrate. 



It appears from these facts thai the inferior action of ammonia nitrogen sometimes 

 observed in practice may no1 be due to inherenl superiority of nitrate, bul to unlike 

 physiological and other conditions which interfere with the biological processes in 

 the soil, fn almost all of the Bterilized pots the application of soluble forms of nitro- 

 gen gave smaller yields or no increase of yield as compared with pots receiving no 

 nitrogen. Tins resull is also attributed to interference with biological procet 

 Cultivated plants not only utilize ammonia nitrogen but generally assimilate it to the 

 same extent as nitrate nitrogen. Nitrification is therefore nol ry for the 



growth of cultivated plant.- as is generally supposed. Beets and potatoes represenl 

 extremes in this respect among the plants experimented with. The results in 

 general do not warrant the changing of recommendations based on the importance 

 of nitrification, since this process is useful in rendering insoluble soil nitrogen avail- 

 able for plants. 



The influence of fertilizing- and of plant growth on soil properties and 

 soil exhaustion, \V. Krugeb I Landw. Jahrb., 84 I 1905), No. 5, pp. 783-804, pi. /, 

 dgms. J: abs. in <'h>m. Centbl., 1906, I. No. /, /,. 72). In connection with the Btudy 

 of nitrification noted above, it was observed that the soils receiving different treat- 

 ments were very variable with reference to their behavior when shaken up with 

 water an allowed to settle, and that their contenl of soluble lime and magnesia, 

 as well as the proportions of these constituents which were precipitated when 

 sodium carbonate and hydrate were added in the tests for ammonia, varied within 

 wide limits. 



Tin- experiments here reported were designed to further study the nature and 

 cause of these variations. They were made in pots each containing 'i kg. of the 

 same soil mixture used in the nitrification experiments, to which there were added 

 in different cases, in addition to the basal fertilizer of phosphoric acid ami lime. 

 ammonium sulphate furnishing 2 gin. of nitrogen), potassium nitrate I 14.4 gin.), 

 and sodium nitrate (12.1 gm. i, eh lorid (8.4 gm. i. sulphate ! in. 1 gm., water-free), 

 carbonate (7.6 gm.), and hydrate (5.7gm.). 



Series of experiments were made with potatoes, mustard, oats, barley, and fodder 

 beets. It was observed in all cases, though more marked with some crops than 

 with others, that the application of nitrate of soda reduced the porosity of the soil, 

 increased the tendency to puddle, and interfered with settling when the soil was 

 shaken with water and allowed to stand, it also increased the tendency to form 

 crusts and clods. These results are attributed to the accumulation of soda in the 

 soil, with consequent fori nation of sodium carbonate. The application of ammonium 

 sulphate resulted in an increase in solubility of lime and magnesia compounds in 



the soil. Sodium salts, especially sodium carbonate, reduce the solubility of these 



substances. 



Fixation of atmospheric nitrogen by plants, Trabut (Bid. Agr. Algerit et 

 Tunisie, II (1905), Nos. ?S, pp. 518-516; 94, pp. 587-547, fig. 1).— This is a general 

 discussion of the subject, summarizing the more practical results of investigations on 

 the fixation of nitrogen by leguminous plants and the various methods of soil inocu- 

 lation to promote such fixation which have been proposed. 



The utilization of atmospheric nitrogen by means of micro-organisms, R. 

 Thiele (Landw. Vers. Slat, 63 (1905), No. 8-4, pp. 161-888, figs. 5; abs. in Jour. 

 Chem.Soc. [London],90\ 1906), No.580, TI t p. 114).— This article reviews the present 

 knowledge relating to Azotobacter, and reports a series of studies of the behavior ol 

 the organism in various liquid and solid media; the occurrence of Azotobacter in dif- 

 ferent sods and its culture in sterile soil; the variation in the nitrogen content of held 



