318 EXPERIMENT STATIOK RECORD. 



It was found that the nature of the soil, as well as the nature of the nitrog- 

 enous matter, marlvedly modified the ammonifying powers of an organism, there 

 being no regularity or certainty in these variations; but every organism did 

 best with a definite combination of soil and organic matter. B. tumescens ap- 

 peared on the whole to be the most efficient organism tested. 



In sandy soil as a medium B. culgaris was the most efficient ammonifier 

 with dried blood; B. mesenteric us with tankage; B. tumescens with cotton- 

 seed meal; B. vuhjaris with fish guano; B. mijcoidcs with bat guano; B. mega- 

 therium with sheep and goat manure; and 8. Intea with peptone. Using the 

 clay loam soil as a medium B. proteus vulgaris was the most efficient with 

 dried blood; B. tumescens -with tankage; Streptothrix aix with cotton-seed meal ; 

 and B. megatherium with fish guano. Using the clay adobe soil as a medium 

 B. tumescens was the most efficient with dried blood; 8. lutca with tankage; 

 B. tumescens with cotton-seed meal ; and B. vulgaris with fish guano. 



The highest efficiency in a single culture with a fertilizer was show'n by 

 B. mycoides in bat guano and in a single culture with ijeptone by S. lutea. 

 A comparison of availability of nitrogenous fertilizers with ammonifiability as 

 a criterion showed tankage, fish guano, and cotton-seed meal to be superior in 

 most or in many cases to dried blood. Some of the organisms tested, particu- 

 larly B. icteroides and P. fluoresvcns, were consistently weak ammonifiers. 



Nitrogen accumulation in continuous rye culture, P. Ehkenberg (Fiihling's 

 Landu: Ztg., 63 (iW^), No. 5, pp. 178, 179).— The author defends his views as 

 set forth in a previous article (E. S. R., 30, p. 424). 



Nitrogen and organic matter in dry-farm soils, R. Stew'art and C. T. 

 HiEST {Jour. Amer. Soc. Agron., 6 (191Ji), No. 2, pp. 4^-56). — Studies of the 

 nitrogen and humus content of virgin soils, and soils which have been dry- 

 farmed (by continuous cropping or summer fallowing) for different lengths 

 of time, in the Bear River, Salt Lake, and Juab valleys of Utah, yielded results 

 and conclusions similar to those obtained in previous work in the Cache Valley 

 (E. S. R., 24, p. 422). That no marked decrease was shown in the nitrogen 

 and humus supply of the surface-cultivated, dry-farm soils " is probably due 

 to the deep-rooted character of the wheat plant when grown under dry-farm 

 conditions and to the fact that very little erosion takes place by wind or 

 water." 



Sulfofication in soils, P. E. RitowN and E. H. Kellogg (Science, n. ser., 39 

 (1914), No. 1012, pp. 764, 765). — In this article it is maintained that soils have a 

 definite " sulfofying power " (power of producing sulphates from other sulphur 

 compounds) which may be determined in the laboratory as follows: 



Add 0.1 gm. of a sulphid, or of sulphur, to 100 gm. of fresh, uncontamiuated 

 soil, and bring the moisture conditions to the optimum by additions of sterile 

 water. Incubate the soils for from 4 to 5 days at room temperature, after 

 which leach out the sulphates by shaking for 6 hours with water. The sum of 

 the sulphate content of the soil itself and the purely chemical oxidation of the- 

 sulphid occurring upon shaking, subtracted from the total sulphate content of 

 the soil after incubation, gives the sulfofying power of the soil, or the physio- 

 logical efficiency of the sulphur oxidizing bacteria in the soil. 



The awakening" of the soil, A. Muntz and H. Gauuechon (Ann. Set. Agron., 

 4. ser., 2 (1913), II, No. 1, pp. 1-15, fig. 1). — This is a full account of investiga- 

 tions briefly noted elsewhere (E. S. R., 20, p. 722). 



The fertility of the soil, B, P. Smoot (Missouri Bd. Agr. Mo. Bui. 12 (1914), 

 No. 3, pp. 31). — It is the pui-pose of this bulletin to present in popular form the 

 scientific facts underlying the principles of soil fertility and soil management. 



The benefits of deep plowing and of maintaining the humus supply in soils 

 are particularly emphasized and the keeping of live stock is discussed In its 



