46 EXPERIMENTS IN BLUEBERRY CULTURE. 



NITROGEN IN KALMIA PEAT IN THE FOKM OF NITRATES. 



(Deteriuiuiitious made by Mr. Karl F. Kellermaii.) 

 Sample. Per cent. 



7 0. 0012 



8 . 0022 



9 . OOOS 



10 . 0013 



11 . 0025 



12 . OOOS 



Average of nitrate nitrogen .0015 



(17) The deficiency of available nitrogen in the acid peaty soil in which 

 the swamp blueberry grows best is due to the inability of the nitri- 

 FYING bacteria TO THRIVE IN SUCH A SOIL BECAUSE OF ITS ACIDITY. 



In order to understand the conditions antagonistic to nitrification 

 which exist in good bhieberry soils it is necessary first to discuss the 

 source and transformation of nitrogen in ordinary soils. 



The available nitrogen in the soil, such as is absorbed by an ordi- 

 nary plant, is commonly derived, unless fertilizers have been ap- 

 plied, from the decomposition of the hunnis contained in the soil, 

 and the humus is itself a product of the decomposition of plant and 

 animal remains. These remains consist ordinarily and chiefly of the 

 partially rotted leaves, stems, and roots of i^lants. 



In the older agricultural literature the name humus was applied 

 to a particular kind of soil which is more properly covered by the 

 terms vegetable mold, leaf mold, and woods mold. (See p. 2-i.) 

 Later the application of the word humus was restricted to that por- 

 tion of a soil consisting of the plant and animal remains, in whatever 

 stage of decomposition. The proper designation of these remains is, 

 however, organic matter. In the sense just described the word humus 

 is still frequently used, but not with correctness and precision. 

 Humus, as now understood by agricultural chemists, represents a 

 stage in the decomposition of organic matter in which the cellular 

 structure has wholly disappeared and the original substance is or at 

 some stage has been entirely dissolved. 



Since it is often necessary to allude to organic matter in the earlier 

 stage, as distinguished from organic matter as a whole, which in- 

 cludes the humus stage as well, the term cellular organic matter, or. 

 more simply still, cellular matter, is suggested as a convenient desig- 

 nation. In cellular matter the cellular structure of the animals or 

 plants still remains and may be detected either by the eye or by the 

 mici'oscope. 



Humus, which is a complex mixture of diverse substances, does not 

 ordinarily exist in the soil in a dissolved condition, but is usually 

 combined with lime or magnesium. The resultant compounds, often 

 indiscriminately blanketed under the names calcium and magnesium 



193 



