DEFICIENCY OF NITKATES IN BLUEBERRY SOILS. 45 



which it has been found to occur on healthy phmts and its frequent 

 absence or scarcity on sickly plants are facts suggestive of a bene- 

 ficial influence. The nature. of this beneficial influence is discussed 

 on pages 48 to 50. 



(16) The acid peaty soils in which the swamp blueberry thrives are de- 

 ficient IN "available" nitrogen, although containing large amounts 



or " NONAVAILABLE '" NITROGEN. 



Ordinary agricultural plants absorb their nitrogen from the soil 

 in the form of nitrates. Whether any are able to utilize directly 

 other forms of nitrogen, particularly ammonia nitrogen, has been the 

 subject of much experiment and of discussion by many authors. It 

 is true in general, however, that the common plants of agriculture 

 when their other food requirements are satisfactory make their 

 growth in direct proportion to their ability to secure their nitrogen 

 in the form of nitrates. For this reason the processes of agriculture 

 are largely devoted to the securing and maintenance of conditions 

 that will bring about the transformation of nonavailable nitrogen 

 into nitrates. Soils in which this can not be done without gi-eat 

 expense in proportion to their productiveness are generally con- 

 sidered poor. 



The acid soils in which wild blueberries thrive are always looked 

 upon as infertile in their natural state, and unless these soils are 

 extensively manipulated cultivated plants do not do well in them. 

 AVhether or not a part of this infertility is due to the directly injuri- 

 ous effect of acid or other poisonous substances, it is known that the 

 conditions existing in these soils are directly antagonistic to the for- 

 mation of nitrates. (See p. 47.) 



That kalmia peat, the soil found in these cultures to be most suc- 

 cessful for blueberries, is deficient in nitrates, although containing an 

 abundance of nitrogen in other forms, is shown by the following 

 nitrogen determinations : 



TOTAL NITROGEN IN KALMIA PEAT. 



(Deteniiiiiatioiis uiadi' by Mr. T. C. Tre(<L-ott.) 



Sample. Per cent. 



1 : 0. 95 



2 1. 4(5 



3 1. IS 



4 1. in 



5 1.40 



G 1. 12 



Average of total nitrogen 1.21 



