464 Ansfewandte Botanik. 



to^ 



ammonium sulphate most readily and dried blood least easil\\ whe- 

 reas the soils from other states nitrified dried blood most readily 

 and ammonium sulphate least easily. 



Excessive nitrates did not appear to interfere seriousl}' with 

 the nitriiication process, provided the chlorine content was low, 

 but excessive chlorine inhibits nitrification. 



L. O. Overholts (St. Louis). 



Schreiner, O. and B. E. Bro^vn. Occurrence and nature 

 ofcarbonized material in soils. (U. S. Dept. Agr. ßur. 

 of Soils Bul. XC. p. 1—28. pl. 1—6. 1912.) 



The buUetin deals with that portion of the organic matter of 

 soils which is ordinarily insoluble in water, alkali, or the usual 

 organic solvents. This residue is classified as organized or unorga- 

 nized depending on whether the original structure is apparent. The 

 former, made up of larger particles, is the part dealt with in this 

 paper. Anah'ses on a large scale were made of a great manj^ soils 

 of different types from various parts of the countr}'' and those in- 

 soluble organic particles isolated and separated into classes. The}' 

 were found to consist of plant material, insect remains, charcoal, 

 coal, lignite particles, etc. The origin of these in the soil is discus- 

 sed and also their influence on ^total organic determinations. It is 

 suggested that depending on its solubilit}' organic matter in the 

 soil is either active or inactive as regards soil fertility. 



M. C. Merrill (St. Louis). 



Schreiner, O. and J. J. Skinner. Nitrogenous soil con- 

 stituents and their bearing on soil fertility. 

 (U. S. Dept. Agr. Bur. of Soils Bul. LXXXVTI. p. 1-84. pl. 1-11. 

 1912.) 



The effect on plant growth of nitrogenous soil Compounds is 

 the experimental work here reported. In their nature and compo- 

 sition these substances cover a wide ränge. The method used was 

 to grow the plants in aqueous Solutions containing either nitrate, 

 Phosphate, or potassium salt alone, or in combination with one or 

 both of the other salts, in a concentration of 80 parts per million, 

 to which the organic Compound to be tested was added in amounts 

 ot usually 50 parts per million. By frequent changes and analyses 

 the condition of Solution was determined, while direct Observation 

 showed the effect on the plants. With one exception the soil organic 

 nitrogenous Compounds were beneficial to the plants and it was 

 found that they could replace nitrate in plant growth. Some of the 

 other substances tried were beneficial, some harmful to plant growth. 

 It is believed the evidence shows that these organic Compounds are 

 absorbed b}'' the plant in the same way as mineral nutrients and 

 enter into the cell where the}^ exert their effect, either benificial 

 or otherwise. An extensive table is appended giving the effects of 

 these Compounds on growth. Their source, occurrence, and chemical 

 relationship are also given. A bibliographv is included. 



M. C. Merrill (St. Louis). 



A-useestehen : ST October 1P14. 



Verla? von Gustav Fischer in Jena.. 

 Kuchdrucksrei A. W. sythoff in LeidiTi. 



