818 EXPEBIMENT STifrlON RECORD. 



grown iu the greenhouse on soils low in sulphur, but supplied with an abun- 

 dance of nitrogen, phosphorus, and potassium contained no sulphates. 



"Where no sulphates were added to the soil, 90 per cent or more of the 

 total sulphur was found in the form of unoxidized sulphur, probably in proteins. 

 In the normally grown plants examined this was from 50 to 65 per cent of the 

 total. The plant was evidently very economical of its supply and made healthy, 

 vigorous growth where no sulphates could be found in the tissue." 



A bibliography of 24 references to literature on the subject is given. 



Some soil changes produced by micro-organisms. W. G. Sackett (Colorado 

 Sta. Bui. 196 (lOlJt), pp. 3-39, pis. 3).— This is a popular discussion of the 

 nature and activities of soil bacteria, yeasts, and molds, with particular refer- 

 ence to the decomposition of orgaiuc matter, the transformation of carbon and 

 nitrogen, and the changes in mineral substances. The most space is devoted to 

 the trasforma tion of nitrogen, under which are discussed ammouification, nitri- 

 fication, denitrification. and j^ymbiotic and nonsymbiotic fixation of atmospheric 

 nitrogen. In this connection data previously reported (B. S. R., 30, p. 818) are 

 reviewed. 



Ammonification and nitrification studies of certain types of Oregon soils, 

 T. D. Beckwith, a. F. Yass, and R. H. Robinson {Oregon Sta. Bui. 118 (1914), 

 pp. JfO. fl'ys. .W). — This bulletin reports a study of the number and kinds of 

 bacteria in certain widely different types of Oregon soils and of the effect of 

 moisture, soil acidity, and lime upon the numbers and activities of these organ- 

 isms, an attempt being made especially to correlate the number of bacteria 

 present in the soil and the amounts of ammonia and nitrate nitrogen produced. 

 The soils used were of two main groups, namely, those of western Oregon which 

 are generally acid and deficient in lime and those of eastern Oregon which are 

 neutral or slightly alkaline and abundantly supplied with lime. It was found 

 that the number of bacteria in soils low in organic matter was small as com- 

 pared with the number in peat and muck soils. The application of lime was 

 without effect upon the number of bacteria except in acid soils or when large 

 amounts of organic matter were added. There was a direct correlation between 

 amounts of ammonia formed and the number of bacteria. 



The ammonifying and nitrifying jwwers of the soils of western Oregon were 

 favorably influenced by the application of lime. The ammonifying powers of 

 the soils varied greatly, the light soils producing the greatest amount of 

 ammonia when nitrogenous substances were added. 



The unit ammonifying power of the organism also varied greatly, the organ- 

 isms in some types of soils being much more active than those in others. It was 

 foimd that the greater the number of bacteria to a gi-am of soil the less the 

 amount of ammonia produced per unit numjier. 



On the influence of soils and of the water content on nitrogen changes, 

 W. P. RoBsoN (Ubcr den Einfluss dcr Biklen und des Wassergehaltes auf die 

 Stiekstotfumsetzungcn. Inang. Diss., Univ. Halle-Wittenberg, 1913, pp. 91). — 

 Studies were made of changes in nitrogen compounds in the natural organic 

 matter of soils and in ammonium sulphate and horn meal in sandy loam and 

 clay soils with vaiying amounts of water (0, 12. and 18 per cent in sandy soil; 

 8, 16, and 24 per cent in loam, and 8, 18, and 28 per cent in clay>. The effect 

 of the addition of sulj)hur on the.se changes was also .studied. 



With low moisture content the transformation of organic nitrogen was more 

 rapid in sandy soils than in the hea^-y soils, while with higher moisture content 

 there was very little difference. In all cases the nitrification of ammonium sul- 

 phate was more rapid the higher the water content. In sandy soils 07 iter cent 

 and in loam and clay soils 100 per cent of the ammonium sulphate applied h.id 

 been transformed into nitrate at the end of the experiment. In the sandy .soils 



