134 



Humus: Nature and Formation 



Table 27. Chemical Nature of the Organic Matter of Soils Described in 



Table 26 



On basis of total organic matter (C X 1.72). 



Peat as Humus 



Peat represents a type of humus which has originated as a result 

 of decomposition of plant materials in areas submerged in water. 

 It comprises various organic formations spoken of also as "muck," 



Woody peat 

 Hypnum peat 

 '.I Glacial till 



llllllllllll Sphagnum peat 

 I I Sedge peat 

 I I Reed peat 



Fig. 58. Different layers in peat profile (from Stokes). 



"turf," "peat moss," and "black humus." The physical and chemical 

 differences found among the different types of peat are due largely 

 to the nature of the plants from which they have been formed, 



Lowmoor peat, frequently spoken of as "muck," is produced prin- 

 cipally from reeds and sedges; it is slightly acid in reaction (pH 5.0- 

 6.0 ) and contains 5-10 per cent mineral matter and 2-4 per cent nitro- 

 gen. Peat moss, or highmoor peat, is formed from sphagnum and 



