146 University of California Fnblications in Agricultural Sciences [Vol. 1 



tion. Of the three organisms showing the highest efficiency, as 

 above indicated, in transforming the nitrogen of dried blood to 

 ammonia. B. vulgaris appears in its turn to be the most vigorous, 

 though the other two approach it closely and are about equal 

 among themselves. 



Clay-Loam Soil 



When the clay-loam soil is used as the medium with dried 

 blood, marked differences are apparent in the efficiency of all 

 the organisms. The poorer air supply of the clay-loam soil, due 

 to its fineness and much greater tenacity, are evidently inimical 

 to ammonia production, even though the same source of nitrogen 

 — dried blood — is supplied for the ammonification process. The 

 largest amount of ammonia produced in this series was that by 

 B. proteus vulgaris, and even that was little more than one 

 quarter of the amount produced b}- B. vulgaris as above noted 

 in the sandy soil. 



Moreover, the most efficient transformers of the nitrogen in 

 dried blood in the sandy soil medium are not necessarily the 

 same as those in the clay-loam soil. For example, in the case of 

 the clay-loam soil B. proteus vulgaris is the most efficient 

 ammonia producer with dried blood as ammonifiable material, 

 while in the sandy soil the same organism manifests less than half 

 the ammonifying efficiency of B. vulgaris. This latter organism, 

 however, stands second to B. proteus vulgaris in efficiency in 

 the clay-loam soil and yields 7.49 mgs. of ammonia nitrogen as 

 against 9.10 mgs. produced by the last-named organism. There 

 appear to he four other organisms which approach the efficiency 

 of the two just discussed in the clay-loam soil in the following 

 order: Mic. tetragenus, B. ramosus, Streptothrix, sp., and Ps. 

 putida. While the latter does not compare in efficiency in the 

 clay-loam soil with that shown by it in the sandy soil, it still 

 manifests a notable efficiency. Sarcina lutea, however, appears 

 to have lost in the clay-loam soil the marked ammonifying power 

 possessed by it in the sandy soil. 



Of course it must be again emphasized that the amounts of 

 ammonia produced by all the organisms in the clay-loam soil 



