624 EXPERIMENT STATION RECORD. [Vol.41 



may have been due to the liberation of formaldehyde by the hexamethyl- 

 enetetramin through the action of dilute soil acids, which caused partial 

 sterilization. 



The search for toxin producers, R. Greig-Smith {Proc. Linn. Soc. N. S. 

 Wales, 43 {1918), pt. 1, pp. 142-190). — Experiments to determine the origin of 

 toxins in soils are reported in which certain soil bacteria, molds, and amcebse, 

 all reasonably supposed to be capable of furnishing substances of a toxic nature, 

 were grown in various media and under varying conditions. In all cases, the 

 signs of toxicity which became manifest could be attributed to an alteration in 

 the reaction of the media. 



"The test organism, Bacillus prodigiosus, grows best in a neutral medium, 

 and an indicator is required which will indicate strict neutrality. The methyl- 

 orange numbers are too high and the phenolphthalein too low. Small diver- 

 gences from the neutral point strongly affect the growth. The humus of 

 leaf-mold contains two types of humic acid ; one absorbs alkali from alkaline 

 carbonates, and the other from alkaline carbonates and hydrates. These were 

 present to the extent or one part of the former to three of the latter. Heating 

 the humus increases the amount of acid, and the increase is largely soluble in 

 water. The effect of reaction is quite of a different order from the evidence of 

 toxic action obtained in former researches." 



Unproductive soils, L. Grimaldi {Le Teire Difficili. Casale Monferrato: 

 Marescalclii Bros., 1917, pp. VIII -\-9S). — This pamphlet deals with the treat- 

 ment and cultivation of acid peat and swamp soils, heather soils, sands, alkali 

 soil, soils containing hardpan and mineral acids, siliceous and rocky soils, arid 

 soils, and generally worn-out soils as they occur in Italy. A specially inter- 

 esting feature is the dynamiting of rocky soils preliminary to cultivating. 



Timely soil topics, F. E. Bear, J. F. Barker, F. A. Bachtell, and R. B. 

 Dustman (Coliimhus, Ohio: Authors, 1919, pp. 108, pis. 14). — This volume is 

 the outgrowth of a series of 4-page pamphlets written monthly during the year 

 1918-19 by members of the department of agricultural chemistry and soils of 

 the Ohio State University, and consists of the material contained in the first 

 thirteen numbers, revised and rearranged. It deals with the management of 

 soils with reference to the production of common farm crops, taking up 

 especially the varying uses of fertilizers on soils for different crops and the 

 preparation of soils for different crops. 



Experiments to determine the best systems of soil management for the 

 most important soil types in Missouri, M. F. J.Iiller, F. L. Duley, and B. W. 

 Tillman {Missouri Sta. Bui. 163 {1919), pp. 68-71, fiys. 3 ) .—Experiments on 

 14 different fields are summarized. 



As an average of all trials a ton of barnyard manure gave a crop increase 

 valued at $4.20 at present crop values. As an average of all experiments the ad- 

 dition of 300 lbs. of steamed bone meal brought a return in four years of ap- 

 proximately $20 an acre. An addition of 400 lbs. of acid phosphate brought a 

 return of about the same amount. Rock phosphate additions just about paid 

 for their cost during a period of from 6 to 10 years. The return from a ton of 

 ground limestone was approximately $8. Green manuring with cowpeas gave 

 generally good results. 



Soil fertility experiments, C. B. Williams {North Carolina Sta. Rpt. 1918, 

 pp. 23-28). — This is a brief sketch of the plan of soil fertility experiments at 

 different farms of the station, together with a statement of results so far 

 obtained. 



Among the more important results it was found that at the Iredell sub- 

 station mineral nitrogenous fertilizers, sodium nitrate and ammonium sulphate, 



