SOILS FERTILIZERS. 619 



the form of monamino acids, about one-quarter in the form of amids, and tlie 

 rest of the nitrogen represents diamino acids. 



" Through weathering, the organic nitrogenous bodies present in the brown 

 peat change quite slowly." 



Organic nitrogenous compounds in peat soils, S. L. Jodidi (Jour. Amer. 

 Chem. Soc, 32 (1910), Xo. 3, pp. 306-.'ilO).—A briefer account of the investiga- 

 tions noted above. 



On the fertility of soils with regard to phosphoric acid, A. Kostzyelyetz- 

 Kn (Zhur. Opuitn. Agron. (Russ. Jour. Expt. Landw.), 10 (1909), No. 4, pp. 

 .',Ji9-Ji83) . — This is a further and more detailed account of investigations which 

 have already been briefly referred to (E. S. R., 22, p. 424), indicating that the 

 growth of Aspergillus niger in nutritive solutions furnishes an index of the 

 amount of phosphoric acid present. It was found that phosi)horic acid consti- 

 tutes about 1/200 part of the weight of the mycelium of this fungus. 



Experiments are reported which were undertaken to determine the age at 

 which the mycelium completes its growth as well as the percentage of phos- 

 phoric acid in the full-grown mycelium. It was found that when the minimum 

 of phosphoric acid (not exceeding 0.025 per cent) was used the Aspergillus 

 completed its growth in 18 days and was capable of absorbing the total amount 

 of phosphoric acid present in this time. The results obtained with the Asper- 

 gillus agreed closely with those obtained by extracting podzol soil with citric 

 acid and chernozem soil with oxalic acid. 



A'arious conditions affecting the growth of the Aspergillus were studied and 

 ai'o reported upon. 



The plant food minimum and phosphoric acid, J. P. Wac.ner (Dciit. Landw. 

 frcsse, 36 (1909), Nos. 43, pp. ^59, ^60, flgs. 2; JfJ,, pp. J,72, ri3; 'i-J, PP- -'fS3, 

 J,HJ,, flgs. 2; ',6, pp. i91, Ji92; abs. in Zentbl. Agr. Chem., 38 (1909), No. 12, pp. 

 804, SO')). — The author explains the importance of evenly balanced fertilizing 

 and discusses the cheapest and simplest means of correcting soil deficiencies 

 in plant food with particular reference to deficiencies in phosphoric acid. The 

 discussion is based upon and illustrated by results obtained with varying 

 amounts of Thomas slag in connection with other fertilizing materials on a 

 large number of different kinds of soils in Alsace-Lorraine, Luxemburg, and 

 Rheinfalz during 1907 and 1908. While the results are mainly of local impor- 

 tance th£.y show that, as a rule, Thomas slag can be freely used even in excess 

 of the requirements of a given crop with reasonable assurance of ultimate profit. 



Contribution to investigations on the utilization by plants of plant food 

 occurring in minimum, E. A. Mitscherlich and K. Celiciiowski (Landw. 

 Jahrh., 39 (1910), No. 1, pp. 133-156). — This is a continuation of previous 

 experiments (E. S. R., 22, p. 223), and gives the results and conclusions from 

 pot experiments with oats grown in sand with phosphoric acid in minimum. 



The results of the experiments showed in general that with like conditions of 

 growth the percentage utilization of the carbon dioxid soluble plant food in 

 minimum was the same. It was not dependent upon the amount of the plant 

 food supplied. Since, according to the law of minimum, the yield of the plant 

 increases in logarithmic function with the amount of fertilizer applied, it 

 follows that the plant yield increases in logarithmic function with the amount 

 of plant food in minimum which is assimilated. 



Under like conditions of growth the percentage utilization of a plant food in 

 minimum varies when the plant food is supplied in two fertilizers varying in 

 solubility. The percentage content of plant food in the plant also \'aries under 

 such conditions, that is, with the same yield there may be a very different per- 

 centage of the plant food in minimum in the plant. The percentage increase in 



