122 EXPERIMENT STATION RECORD. 



mote the activity of desirable micro-organisms and retard the development of 

 the undesirable ones. And as we recognize that bacterial growth is an impor- 

 tant factor in the transformation of various materials into available plant food, 

 we appreciate the importance of further investigation for securing more exact 

 and more complete data bearing upon the interdependence of agricultural prod- 

 ucts and the micro-organisms of the soil." 



The bacterial flora as a factor in the unproductiveness of soils, A. Dach- 

 NOWSKi (Ohio Nat., 10 (1910), No. 6, pp. 131i-l-i5, figs. 2). — This is a continua- 

 tion of investigations previously noted (E. S. R., 22, p. 22) and gives the results 

 of investigations with cultures or organisms obtained from bog water and soils. 



Wheat seedlings were grown in solutions inoculated' with these cultures and 

 the effect uijon transpiration noted. Reduction of transpiration of from 20 to 

 52 per cent was noted in inoculated cultures. 



The author believes that " the i-esults show clearly that the retardation in 

 growth of wheat plants is not caused by physical or chemical conditions but 

 through the direct activity of the bacterial floi'a. It has long been suspected 

 that a reciprocal relation exists between groups of soil bacteria and the plants 

 growing upon the soil. Various writers have been able to point out that marked 

 differences in the productive power of different soils followed the growth of 

 wild plants, and that these differences persist for some time. It is generally 

 concluded therefore, that the injury caused to cultivated plants by weeds or 

 previous crops might be due to influences on the bacterial life in the soil, and 

 in a direction unfavorable to succeeding agricultural ci'ops. That such relations 

 exist the writer is convinced in view of the evidence presented above. No doubt, 

 the ' exhaustion " of soils which is frequently met with, and which can not 

 always be attributed to the removal of plant nutrients, is, in part, an allied 

 phenomenon." 



The balance of life in the soil (Agr. Neivs [Barbados], 9 (18d0), Nos. 202, 

 pp. 17-19; 203, pp. 33, J'/). — This is an article based upon the investigations of 

 Russell and Hutchinson (E. S. R., 22. p. 121), which indicated in general "that 

 the number of bacteria in the soil is limited by the presence of comparatively 

 large, competing and destructive organisms, and that the increased fertility of 

 soils that have been partially sterilized is due to the killing of these and the 

 consequent increase in the rate of production of bacteria, with the concomitant 

 increase in the rate of formation of ammonia." 



Gain and loss of nitrog-en in cultivated soils, A. Koch (Mitt. Dent. Landw. 

 GeselL, 25 (1910), No. 12, pp. 173-175). — This is a popular account of investiga- 

 tions, a technical account of which has already been noted (E. S. R., 22, p. 428). 



Nitrog-en-ftxing' bacteria and nonleguminous plants, W. B. Bottomley 

 (Nature [London], S3 (1910). No. 2108, p. .96).— This is a further short contri- 

 bution to the controversy on this subject already referred to (E. S. R., 22, pp. 

 122. 128). 



Seasonal nitrification as influenced by crops and tillage, C. A. Jensen 

 (V. S. Dept. Agr., Bur. Plant Indus. Bui. 173, pp. 31, figs. 7). —This bulletin 

 reports the results of investigations on seasonal changes in the water-soluble 

 nitrates in summer fallowed land, wheat land, and corn land down to a depth 

 of 24 in., and the rates and extent of the seasonal removal of the nitrates by 

 these crops, made in connection with cultural experiments on the Bellefourche 

 (S. Dak.) substation of the Bureau of Plant Industry of this Department. 



The maximum amount of nitrates was found in the surface 6 in. of the soil 

 in the early part of the spring. Thereafter there was a decrease in the nitrate 

 content of this layer and a progressive increase downward. 



" The respective soil layei-s in the fallow plat reached their individual 

 maximum accumulation of nitrates about a week earlier than the correspond- 

 ing layers in the wheat plat. . . . 



