SOILS FERTILIZERS. 523 



'balanced' solutions, before we have reacbetl a logical stopping place for these 

 lines of research."' 



The need of further carefully controlled experiments on this subject is 

 pointed out and some of the conditions under which such experiments should 

 be made are explaineil. A bibliography of 19 references to the literature of the 

 subject is given. 



The carbon dioxid content of soils during different stages of growth of 

 plants, P. Barakov (Zhur. Opiiitn. Agron. (Russ. Jour. Expt. Landw.), 11 

 (1910), No. 3, pp: 321~3-',3, figs. //).— Examinations of the air of different soils 

 in lysimeters planted to various crops showed that the carbon dioxid content of 

 the air was insignificant at the beginning of vegetation, increasing rapidly and 

 reaching its maximum at the blooming period, then declining rapidly and reach- 

 ing its minimum at the period of ripening. The more fertile the soil and the 

 greater the plant growth the larger was the carbon dioxid content. The carbon 

 dioxid was derived mainly from the respiration of the plant roots, and this 

 varied with difierent plants at different stages of growth. With lupines the 

 maximum was reached at the blooming stage, with oats about two weeks before 

 blooming. With barley respiration was less active than with oats, and it was 

 still less active with winter cereals, especially wheat. Root and tuber plants 

 slowly reacheil their maximum and slowly declined. With potatoes the maxi- 

 mum of carbon dioxid excretion was reached after blooming, with sugar beets 

 at the period of maximum growth. 



Variation in the carbon dioxid of the soil was affected to some extent by the 

 sinking of the moisture of the air into the soil and by the decomposition of the 

 organic matter supplied by green manuring with lupines and vetches, but the 

 latter is ordinarily much less important than the carbon dioxid excreted by 

 plant roots. 



Nitrates in the soil, W. P. Headden {Colorado Sta. Bui. 160, pp. 8). — This is 

 a brief account of investigations which were more fully reported in an earlier 

 bulletin of the station (E. S. R.. 23, p. 221). 



The "acid soil" bugaboo, J. A. Bonsteei. (Gnrd. Mag. [N. Y.], 12 (HUO), 

 No. 1, p. 23). — This article maintains that the litmus paper test for acidity of 

 soils is not reliable except in the hands of an expert, and may indicate a harm- 

 ful degree of soil acidity in many cases where such condition does not actually 

 exist. 



A new viewpoint concerning the fertility of the soil, B. Sjollema {Cultura, 

 22 {1910), No. 259, pp. 108-121). — This is a discussion of the recent additions 

 to the theory of soil fertility, and is based more especially on the work of 

 Russell and Hutchinson (E. S. R., 22, p. 121). 



The fertilizing influence of sunlight, F. Fletcher and E. J. Russell 

 {Nature [Londoni, 83 {1910), No. 2121, pp. 488, .^89).— Further discussion of 

 this subject (E. S. R., 23, p. 123), is given, bearing especially upon the effect 

 of toluene in rendering toxic substances in soils insoluble and the relation of 

 fertility and bacterial activity. 



The American fertilizer handbook, 1910 (Philadelphia, 1910, pp. 2.}6'. flfff^- 

 33). — This contains in addition to the usual directories of fertilizer manufac- 

 turers, cotton-seed oil mills, and allied fertilizer trades, special articles on the 

 National Fertilizer Association, a statistical abstract of the fertilizer industry 

 of the United States, the Peruvian guano deposits, the New York fertilizer ma- 

 terials market, and the Chicago ammoniate market, sulphuric acid tables, notes 

 on cyanamid as a fertilizer annnoniate. the manufacture of sulphate of ammonia, 

 official methods for the analysis of fertilizers and soils, and the potash industry. 



00803°— No. 0—10 3 



