622 EXPERIMENT STATION EECORD. 



tion of the soil organisms which interfere with the activity of the ammonia- 

 forming bacteria. 



Experiments on ammonia and nitrate formation in soils, II, J. G. Lipman, 

 P. E. Bbown, and I. L. Owen {Ccntbl. Bakt. [etc.}, 2. AW., 30 {1911), No. 7-12; 

 pp. 156-181; abs. in Jour. Chem. 8oc. [London], 100 (.1911), No. 585, II, pp. 649, 

 650). — This is a second communication on tliis subject (B. S. R., 23, p. 621), and 

 deals with ammonia formation from dried blood as affected by the mechanical 

 composition of the soil, the amount of moisture and lime present, and various 

 chemical and physical factors. 



It was found that there were considerable losses of ammonia from well 

 aerated soils, that ammonia formation was to a large extent controlled by the 

 moisture content of the soil, that smaller applications of calcium carbonate 

 stimulated ammonification but that larger additions depressed it, and, in general, 

 that the rate of ammonification was controlled by a number of chemical and 

 physical soil factors. 



The authors conclude that the method of measurement of ammonia formation 

 may be used with success " for the study of a great variety of soil problems 

 that concern the formation and transformation of soil humus, and, even more 

 generally, of many problems that belong properly within the domain of soil 

 fertility and plant nutrition." 



The method employed was in brief as follows : " In all cases 100 gm. of ma- 

 terial was employed. Water was added in amounts sufficient to create optimum 

 moisture conditions; but because of the differences in the water holding power 

 of the different ingredients 18 per cent of moisture was allowed for the soil 

 itself, 12 per cent for the sand, and 60 per cent for the dried blood. In each 

 case the soil, or the mixture of soil and sand, was placed in a tumbler; the 

 required amount of dried blood added and thoroughly mixed with the soil, and 

 the material was then moistened, the quantities of water added including the 

 6 cc. of fresh soil infusion employed in each case to provide abundant and uni- 

 form inoculation. The tumblers were covered with a Petri dish cover and kept 

 in the incubator at 27 to 28° C. for seven days; at the end of that time the 

 ammonia was distilled off into standard hydrochloric acid and the distillate 

 titrated against standard ammonia." 



Th.e chemical nature of the organic nitrogen in the soil, S. L. Jodidi (Iowa 

 8ta. Research Bid. 1, pp. 3-Ji6, fig. 1). — ^A study of the organic nitrogenous sub- 

 stances in plats of Wisconsin drift soil treated In different ways similar to that 

 on nitrogenous compounds in peat soils (E. S. K., 22, p. 618) is reported in 

 detail in this bulletin. The same methods were employed in this investigation 

 as in the earlier work, viz, those used by Hausmann and Osborne in protein 

 chemistry. The plan of investigation was based upon the idea that soil organic 

 matter or humus is a resultant of the decomposition of plants all of which con- 

 tain a large if not a predominant proportion of nitrogen in the form of protein, 

 and that in the decomposition of the protein there are formed (1) albumoses, (2) 

 peptones (polypeptids), (3) amino acids and acid amids, (4) ammonia, (5) 

 nitrites, and (6) nitrates. 



The general method of procedure in separating the organic nitrogenous sub- 

 stances was to evaporate the hydrochloric acid extract of the soil practically to 

 dryness and distill it with cream of magnesia, the ammonia obtained by this 

 process representing the amids in the soil. The residue from the distillation 

 with magnesia was extracted with water and the extract, after acidulating with 

 sulphuric acid, was treated with phosphotungstic acid. The precipitate thus 

 obtained contained the diamino acids and the filtrate from this precipitate rep- 

 resented the monamino acids. It was found that by these methods the bulk of 



