1744 SOIL PHYSICS, CHKMISTRY AND MICROBIOLOGY 



Conclusions. — In pot cultures it is possible to regulate the osmotic 

 pressure of the soil solution b}" the addition of soluble salts (nutrient and 

 otherwise) to the soil and thereby not only to increase the Adelds of grain 

 and straw abo\-e the normal, but also to raise their nitrogen content. The 

 study of the osmotic pressure of the soil solution is of special interest in 

 relation to steppe and alkali soils where it is exceptionaly high and in the 

 case of peat soils and bogs where it is exceptionally low. It may also throw 

 light on the action of " indirect " manures, such as for instance that of 

 sodium chloride which is frecjiiently used on sugar beets. Hitherto its be- 

 neficial effect has been looked upon as due to a liberation of potash in the 

 soil, instead of which it might be caused by a simple increase in the osmotic 

 pressure. 



It is recommended that the investigations be extended to other farm 

 crops and the effect of the soil conditions determined not only on the ni- 

 trogen content of the plant but also on its other constituents, fats, sugars 

 and starch. 



1258 - Investigations on the Microoi^anisms of Peat Soils, Waste and Cultivated.— 



Arnd T., ill Centralblatt jiir Baktcriolns,ii\ Parasitenkunde unci Inlehtionskrankht'iten^ 

 Vol. 45, X05. 8-25, pp. 554-574- Jena, June 19, igi6. 



At the Bremen Station for peat investigations (" Moorversuchsstation "), 

 a series of experiments were undertaken to determine the changes, if any, 

 in the bacterial activity of peat soils brought about by drainage, liming 

 and tillage. Only preliminary trials have as yet been accomplished, but 

 these have already shown that there exists a striking difference in bacte- 

 rial activity between waste and cultivated land. Soil samples were taken 

 from tweh'e different parts of the experimental ground and were tested 

 for : ammonification, nitrification, denitrification, the decomposition of 

 cellulose, the presence of Azotobacter and the fermentation of mannite. The 

 results may be summarised as follows ; 



i) Ammonifying organisms were found in all samples, even in the 

 most strongly acid subsoils from waste land. They were far more active 

 in surface soil than in the underlying layers, the actual numbers in the sub- 

 soil being very small and their vitality reduced. Ammonia production also 

 occur ed much more freeh^ with samples from soils which had been tilled, 

 manured or limed than with samples from land of the same type which 

 lay waste. An application of dung to a peat soil which had a very low 

 bacterial content resulted in a considerable and lasting increase in the 

 numbers and activity cf the putrifying organisnis. The breaking up of 

 waste land only affected the bacterial life in the top 8 in. of soil; samples 

 of subsoil (8 t-j 16 in. deep.) showed about the same ammonifying 

 power whether taken from waste or cultivated land. 



2) None of the samples from waste land contained any active nitri- 

 fying organisms, neither did samples from cultivated land which was 

 either unlimed or had onh^ received lime at the rate of half a ton of lime 

 per acre. On the other hand soil which had received one ton of lime per acre 

 exhibited a marked power of nitrification, but it woiild seem tha,t an even 

 heavier dressing would be required in order to obtain an active develop- 



