feOILS FERTILIZERS. 723 



The results with crimson clover and vetch were vitiated by injury by nema- 

 todes, which also injured adzuki beans to some extent but caused no damage lo 

 cowpeas and soy beans. 



It was found that the approximate gain in nitrogen during 5 years with 

 cowpeas and soy beans and with vetch, which was grown alternately with each, 

 " was a ton of nitrogen per acre, about seven-tenths of which was contained 

 in the 25 tons of moisture-free summer crops remo^■ed, and the remainder in 

 the soil itself. 



" These quantities should be considered with reference to the following facts, 

 namely, the soil in the pots was 10 in. deep, somewhat deeper than the surface 

 soil in many localities; the winter vetch was grown in a heated greenhouse; 

 and, furthermore, sufficient water was given to supply all the needs of the 

 plants." 



Nitrates in soils, F. L. Stevens (Abs. in Science, n. ser., 35 (1912), No. 

 893, p. 227). — Results of investigations are cited as throwing doubt upon the 

 usual assumption that nitrates are the chief source of nitrogen for green plants, 

 and the need of bacterially and chemically controlled tests under natural con- 

 ditions to determine what forms of nitrogen are most readily available to the 

 leading crop plants is pointed out. Nitrification and denitriflcation are dis- 

 cussed. " In particular, question was raised as to the influence of organic mat- 

 ter mixed with nitrates in fertilizers (a common practice) upon loss by denitri- 

 flcation. Stress was laid upon the need of conducting tests in soils, not in 

 solutions." 



Azotogen, nitrag'in, and natural soil inoculation, H. von Feilitzen (Centbl. 

 Bald, [etc.], 2. Aht., 32 (1912), No. 13-19, pp. 7,i9-//.5i).— This is a reply to 

 criticisms by A. Koch of the author's work on this subject. 



A contribution to the knowledge regarding Loew's lime-magnesium ratio, 

 R. Stewart (Jour. Indus, and Engim. Chem., 3 ^1911), No. 6, pp. 376-378; abs. 

 in Jour. Soc. Chem. Indus., 30 (1911), No. 13, p. 821). — An examination of the 

 soil of one of the Utah Experiment Station farms showed from 30 to 41 per 

 cent of calcium carbonate and from 11 to 20 per cent of magnesium carbonate 

 to a depth of 8 ft. This soil has been cropped for 40 years without manure 

 as far as the records show. 



The results " show quite clearly that the high percentage of magnesia has no 

 loxic action on the gi'owth of the plants. It is evident that the magnesia does 

 not have any toxic action on plant growth for one of two reasons: First, the 

 ratio of magnesia to lime, which falls within the ratio (1:3), as recently sug- 

 gested by Loew, is favorable to plant growth, or, secondly, the calcium and 

 magnesium are present in the form of a double salt such as CaMg (063)2, and 

 therefore magnesium carbonate, as such, exists in this soil only in small 

 amounts. It seems possible that such a double salt would have a different 

 action on plant growth than would either the magnesium carbonate or calcium 

 carbonate alone," and this suggests the advantage of using magnesian lime- 

 stone for correcting soil acidity. 



Green manuring or bioculture, C. Lumia (Atti R. Accad. Lvncei, Rend. CI. 

 Sci. Fis., Mat. e Nat., 5. ser., 21 (1912), I, No. 2, pp. U0-U5).— The use and 

 (advantages of systems of soil improvement by means of leguminous green 

 manures and mineral fertilizers, as first proposed by Ville and called by him 

 sideration are discussed. 



The influence of bacteria on the soluble phosphorus of manures, W. E. 

 ToTTiNQHAM (Abs. in Science, n. ser., 35 (1912), No. 897, pp. 390, 391).— An 

 abstract of a paper presented at the "Washington meeting of the American 

 Chemical Society in 3911. 



42049°— No. 8—12 3 



