434 EXPERIMENT STATION RECOftD. 



l)ility 111' alkuli salts. No advantage resulted in extending the time of digestion 

 beyond one day. The ex'idence o1)tained was con.«idereil as favoring the use of 50 

 gm. of soil to 1 liter of water. Provisional methods for the analysis of alkali soils 

 were sulnuitted hy the referee. 



Soil acidity was studied hy the referee, whose report upon this subject contained 

 a discussion of the relation of soil reaction to plant growth, a review of the experi- 

 mented work done in this country on partial and complete neutralization, results of 

 extended tests of the sodium cldorid and lime-water methods proposed at the last 

 meeting of the association and described in the proceedings, and a consideration of 

 the nature of soil acidity. From the results of his own experiments relating to the 

 effects of acid and alkaline reactions upon plant growth and a study of available data 

 on this subject, the referee tentatively concluded that a soil slightly alkaline from 

 carbonate of lime furnishes the best condition for the economical production of crops, 

 and that any method for estimating the acidity or the lime requirements of S(jils 

 should be based upon this hyj^othesis. The results by the sodium chlorid and lime- 

 water methods diverged as the amount of organic matter in the soil increased, in 

 most instances higher results, excejit possibly in soils deficient in organic matter, 

 being obtained by the lime-water method. 



Data were submitted which indicate that acidity as determined by the sodium- 

 chlorid method is due to the solution in sodium chlorid of acid-salt-forming leases, 

 plus the water-soluble acids, and that but little, if any, of the difficultly soluble 

 organic acid material is estimated by this method. Only traces of free hydrochloric 

 acid were foiuid in any of the sodium chlorid filtrates from the soil. The lime-water 

 method was believed to show beyond a doubt the amount of lime required under the 

 most favorable condition of distribution to render the soil alkaline. 



The referee believed that work should be directed toward determining how much 

 of the total apparent acidity of soils must be neutralized in order to produce maxi- 

 mum yields economically rather than to further study of these methods. 



The fixation of atm^ospheric nitrogen by bacteria, J. G. Lipmax. — The litera- 

 ture of this subject Avas reviewed and several series of laboratory experiments were 

 reported in detail. The behavior of Azohacter vinelandii isolated by Dr. Lipman was 

 illustrated by the results of experiments in which the organism was grown in solu- 

 tions containing either no nitrogen or only a small quantity of nitrogen. The fixation 

 of nitrogen in cultures was found to increase as the surface exposure increased. The 

 evidence was not conclusive as to the utilization or nonutilization of filter paper by 

 the bacteria as a source of carbon. The presence of filter paj^er in small quantities 

 seemed to increase nitrogen fixation, but when the amount was increased beyond a 

 certain j^oint a retarding effect was observed. A similar influence was noticed as the 

 result of using different quantities of mannite. 



The fixation of nitrogen by A. rbielandii was increased when this species was grown 

 in the presence of a bacillus designated B. 30. A number of other organisms grown 

 with A. vinelandii seemed to exert no influence. The intention of extending the 

 experimental work to actual soil conditions was announced. 



Redonda phosphate, H. J. AVheeler. — It was reported that Kedonda phosphate, 

 which contains from 35 to 40 per cent of reverted phosphoric acid, had been found, 

 in experiments extending over a period of years, to have very little value when used 

 upon an acid soil. When applied to a limed soil the results were very much better. 

 Upon soil limed sufficiently to enable the growth of all ordinary crops in a satisfac- 

 tory manner, but jirobably not alkaline in reaction, this phosphate was nearly equal 

 in value for certain crops to some of the soluble phosi:)hates. This was true of grass 

 during a period of 4 years, but not true of Swedish turnips and beets. Millet and 

 some other i)lants seemed to possess exceptional ability to use this phosphate on 

 both limed and unlimed soils. 



