166 University of California Puhlications in Agricultural Sciences [Vol. 1 



per cent of the total amount of dried-blood nitrogen furnished, 

 and that occurred in only one case, all the other organisms pro- 

 ducing much less. 



The Clay-Adobe Soil 



Some very striking facts become apparent when the avail- 

 ability of the four fertilizers in clay-adobe soil are considered. 

 While on the whole dried-blood nitrogen is only slightly more 

 efficiently transformed into ammonia than in the clay-loam soil, 

 cottonseed meal and tankage, particularly the former, are more 

 vigorously acted on in the clay-adobe soil by most of the organ- 

 isms. Fish guano, while not markedly so, is none the less superior 

 here again to dried blood. 



Again comparing the different fertilizers on the basis of the 

 amounts of their nitrogen transformed into ammonia by the 

 organisms tested, we find that four organisms transform 10 per 

 cent or more of the nitrogen in cottonseed meal into ammonia, 

 a like number accomplish similar results in the case of tankage, 

 and none succeeds in that direction in either fish guano or dried 

 blood. "While thus cottonseed meal and tankage appear alike, 

 a study of table VIII reveals the superiority of the former in the 

 larger absolute amounts of nitrogen which are transformed there 

 than in the case of the' latter. 



The first striking fact shown in Table VIII is the marked 

 superiority of the sandy soil as a medium for ammonification by 

 pure cultures. Likewise the added fact of its superiority as a 

 medium for most of the organisms tested must be noted in this 

 connection. The second point of great interest is the surprising 

 fact of the superiority of the clay-adobe soil to the clay-loam 

 soil as a medium for ammonification. From its tenacious nature 

 one would suppose the former type to be a much poorer medium 

 for ammonification than the clay loam and yet it is distinctly 

 superior to the latter as regards tankage and cottonseed meal. 

 As regards fish guano, it is slightly inferior to the clay loam and 

 again as regards the dried blood about equal to the clay loam 

 or possibly slightly superior. 



Considering all the data given in Table VIII from all points 

 of view, tankage must be given first place as regards the avail- 



