4 BULLETIN 802, U. S. DEPAKTMENT OE AGRICULTURE. 



behavior of the various types of disintegrating plant remains making 

 up a peat deposit, are considered of special importance in drainage 

 projects intended to be practicable from an engineering and agri- 

 cultural standpoint; they are essential for an adequate method of 

 dewatering peat materials that are found to be of value for manu- 

 facturing purposes. It is rather in the knowledge of the different 

 kinds of peat material, the factors in the field which brought about 

 their accumulation and determined their character, that a satisfac- 

 tory basis has been found for the improvement of peat by means 

 of suitable crops or by specific operations in the technical industries. 



Few phases of botanical inquiry have received as much attention 

 as the development and formation of peat deposits ; yet information 

 concerning them appears to be little known and still less considered 

 in practice, though the classical investigations of Andersson (1)/ 

 Clements (4) , Graebner (12), Lesquereux (16),Lorenz (17),Potonie 

 (19), Sendtner (21), Sitensky (22), and especially the works of 

 Frith and Schroter (10), Grisebach (13), Steenstrup (4), Vaupell 

 (23), and Weber (25) are not only comprehensive but fundamental 

 in problems relating to the structure and content of peat deposits. 



The attempt to establish a correlation between vegetation and any 

 one factor of the environment is difficult, and though not all field 

 work is of a nature adapted to throw light on this vexed question it 

 has, nevertheless, been possible to make such a correlation in the lines 

 of physical and chemical studies with types of peat material distinct 

 in botanical composition and in degree of disintegration. Practically 

 all the work is thus far European, and the leading investigations, 

 notably those of Bersch (2), Birk (3), Feilitzin (9), Gully (14), 

 Hoering (15), Minssen (18), Virchow (24), and Zailer and Wilk 

 (26-27), follow for the most part modern botanical viewpoints and 

 definitions. 



The botanical, physical, and chemical nature of the different 

 peat materials is of the widest practical importance, since it is in 

 general more difficult to change the nature of the vegetable mass 

 than to remedy its deficiencies, but almost equally important is the 

 character of the mineral soil underlying the plant remains. The 

 geological relations have their most important significance in the fact 

 that decaying organic matter and carbonated water have a relatively 

 high solvent action on the minerals of soils and rocks. This effect 

 increases with the area covered by the accumulating masses of peat 

 materials and especially with thicknesses in which oxidizing condi- 

 tions are absent. Underlying and marginal soils derived from sedi- 

 mentary, metamorphic, and eruptive rocks, both basic and acid, 

 correspondingly affect the content and quality of peat materials in 



1 The serial uumbers in parenthpses refer to " Literature cited " at the end of this 

 bulletin. 



