TRANSFORMATION OF ORGANIC MATTER 707 



These results point to the practical conclusion that, whenever a readily- 

 available source of nitrogen is wanted immediately, substances con- 

 taining less than 2 per cent of nitrogen cannot be profitably used. The 

 greater the nitrogen content of a material, the greater is its value as an 

 immediate source of nitrogen. Whenever substances with a nitrogen 

 content of less than 2 per cent are added to the soil just before a crop 

 is planted, some inorganic nitrogen fertilizers, like NaN0 3 , (NH 4 ) 2 S0 4 , 

 urea, should also be added, otherwise the growing plants may experience 

 nitrogen starvation. 



Hilgard 101 suggested that soil in which the nitrogen content of 

 "humus" (as determined by the Grandeau method) was only 2 per cent, 

 the application of available nitrogen was essential or the soil is nitrogen- 

 hungry; the presence of 3 per cent nitrogen in "humus" was sufficient 

 to cover the need; a greater content of nitrogen (5 per cent) indicated 

 an abundance of this element. However, as pointed out previously, the 

 amount and nature of "humus" obtained from a soil depends upon the 

 method used. 102 



101 Hilgard, E. W. Zur Erkennung des Diingebedurfnisses der Boden fur 

 Stickstoff. Deut. landw. Presse., 22: 490. 1895. 



102 The carbon and nitrogen ratio of peat materials is discussed in detail by 

 Dachnowski; the bog flora and vegetation by Transeau; the microorganisms living 

 in peat soils by Ritter, Arnd and Christensen ; in forest soils by Migula and 

 Schultz; Dachnowski, A. P. The chemical examination of various peat materials 

 by means of foodstuff analysis. Jour. Agr. Res., 29: 69-S4. 1924; Transeau, 

 E. N. The bogs and bog flora of the Huron River Valley. Bot. Gaz., 40: 351- 

 375, 418-448. 1905; 41: 17-42. 1906; Ritter, G. A. Beitrage zur Kenntnis der 

 niederen pflanzlichen Organismen, besonders der Bakterien, von Hoch- und 

 Niderungsmooren, in floristischer, morphologischer und physiologischerBezieh- 

 ung. Centrbl. Bakt. II, 34: 577-666. 1912; Arnd, Th. Beitrage zur Kenntnis 

 der Mikrobiologie unkultivierter und kultvierter Hochmoore. Centrbl. Bakt. 

 II, 45: 554-574. 1916; Landw. Jahrb., 49: 191-214. 1916; 51: 297-328. 1917; 

 Christensen, R. Mikrobiologische Untersuchungen von Hoch-und Niederungs- 

 moortorf. Centrbl. Bakt. II, 37: 414-431. 1913; Migula, W. Uber die Tatig- 

 keit der Bakterien im Waldboden. Forstwissensch. Zentrbl., 35: 161-169. 

 1913; Schulz, K. Die Verbreitung der Bakterien im Waldboden. Inaug. Diss. 

 Jena. 1913; (Centrbl. Bakt. II, 41: 277). 



