326 EXPERIMENT STATION EECOED. 



percentage of nitrogen was 6.79, and the average cost of nitrogen per pound was 

 24.7 cts. These figures, as well as those given for other organic sources of 

 nitrogen, show that the nitrogen of nitrate of soda, which is unquestionably 

 the most quickly and fully available form accessible, is also the cheapest at 

 present prices. 



Beport of analyses of commercial fertilizers and Paris green, J. E. Halli- 

 GAN {Louisiana Bias. Fcrt. Rpt. 1909-10, pp. 76). — This bulletin reports an- 

 alyses and valuations of 6,599 samples of fertilizers and 1 sample of Paris 

 green examined during the year 1909-10. The fertilizers examined included 

 besides complete fertilizers and other standard fertilizing materials, 2.37 sam- 

 ples of bone meal, 829 samples of tankage, and 408 samples of cotton-seed meal. 

 The quality of the different classes of fertilizers is discussed, and it is shown 

 that there is a tendency for the complete fertilizers to be deficient in nitrogen. 



Commercial fertilizers in 1909-10, G. S. Fkaps {Texas Sta. Bui. 133, pp. 

 ff-18, fig. 1). — This bulletin reports analyses and valuations of fertilizers in-, 

 spected under the Texas fertilizer law during the season 1909-10. It is stated 

 that the quantity of commercial fertilizers exclusive of cotton-seed meal sold 

 during the year in Texas was 34,000 tons as compared with 23,800 tons the 

 previous year. 



AGRICULTURAL BOTANY. 



Soil bacteriological investigations, 13. Heinze {Landio. Jahrh., 39 {1910), 

 Erganzimgsb. 3, pp. 31^-343; ahs. in Chcm. Zcntbl, 1910, 11, No. 6, p. 40Jt).— 

 Investigations begun in 1904 on bacteriological conditions in fallow soils, on 

 the assimilation of nitrogen by different kinds of bacteria, and on nodule-forming 

 bacteria as related to the cultivation of leguminous plants, are reported. 



It was found that repeated cultivation of fallow land materially increased 

 the number of organisms, the number being highest in the summer months and 

 lowest during the fall and spring. Phosphoric acid and potash apparently had 

 no effect on the number of bacteria but aided materially in the breaking down 

 of organic matter. The organic substances (straw, sugar, starch), as well as 

 the organic nitrogenous compounds (asparagin, peptone, albumin), materially 

 increased the number of organisms, although the inorganic nitrogenous com- 

 pounds (sodium nitrate and ammonium sulphate) did not exert an ap])reciable 

 Influence in this respect. Among the most important soil organisms found in 

 the fallow were those which ferment pectin compounds, cellulose, and hunuis, 

 ammonifying and nitrifying organisms, and Azotobacter. For the assimilation 

 of nitrogen, Azotobacter and other organisms require the presence of large quan- 

 tities of organic substances (sugar, starch, cellulose, humus, etc.), the neces- 

 sary mineral compounds, and a neutral or weak alkaline reaction of the soil. 



The author describes a method of culture by which the original strength can 

 be restored to Azotobacter which has apparently been greatly reduced in nitro- 

 gen-fixing power. Humus substances and phosphoric acid were especially fa- 

 vorable to the growth and nitrogen-fixing power of Azotobacter. The nitrogen 

 which was assimilated by Azotobacter and fixed in form of protein compounds 

 was quickly broken down again. 



Lupine-sick and clover-sick soils were restored to normal condition by the ap- 

 plication of inoculated serradella soil. 



Hiltner's recent views regarding the two groups of legume organisms were not 

 substantiated by these investigations, although his earlier conclusions regarding 

 the identity of specific legume organisms were confirmed. All of the more re- 

 cent observations show that serradella and lupines do not show any special pref- 

 erence for sandy soils. An important point brought out in these investigations 

 is that utilization of the nitrogen of the soil and of the air goes on simultane- 



