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Peat (泥炭)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily


[ peat | utilization ( 利用 )| references ]

Peat (泥炭)


Sometimes called turf (also called peat soil (泥炭土) in soil science )

The accumulation and decomposition of peat are greatly reated to global warming because of large carbon sinks

Partially-decayed plant matter that is accumulated mostly in boreal wetlands (湿原), such as in tundra (ツンドラ), when the accumulation of plant matter is faster than the decomposition.
One of the characteristics of peat in Hokkaido is that the peat often contains tephra (テフラ).

  1. moss peat, mostly dominated by Sphagnum → bog (Nishimura et al. 2009)
  2. reed-sedge peat → fen
  3. tropical peat, dominated by wood
von Post scale (フォンポスト尺度)

= von Post (humification) scale (フォンポスト腐植化尺度) assessing peat decomposition
The decomposition of peat is greatly related to global warming, because of carbon emission

Degree of decompositionNature of squeezed liquidProportion of peat extrudedNature of plant residuesDescription
H1Clear, colourlessNonePlant structure unaltered
Fibrous, elastic
H2Almost clear, yellow-brownNonePlant structure distinct, almost unalteredAlmost undecomposed
H3Slightly turbid, brownNonePlant structures distinct, most remains easily identifiableVery weakly decomposed
H4Strongly turbid, brownNonePlant structure distinct, most remains identifiableWeakly decomposed
H5Strongly turbid, contains a little peat in suspensionVery littlePlant structure clear but indistinct and difficult to identifyModerately decomposed
H6Muddy, much peat in suspensionOne thirdPlant structure indistinct but clearer in residue, most remains undefinableWell decomposed
H7Strongly muddyOne halfPlant structure indistinctStrongly decomposed
H8Thick mud, little free waterTwo thirdsPlant structure very indistinct - only resistant material such as rootsVery strongly decomposed
H9No free waterNearly allPlant structure almost unrecognisableAlmost completely decomposed
H10No free waterAllPlant structure not recognisable, amorphousCompletely decomposed

H1 = no decomposition ↔ H10 = complete decomposition

Peat properties (泥炭特性)

Chemical property

Physical property

Kind of organic materialsFibre contentSodium pyrophosphate extract color
Sapric (saprist soil)> 1/3
< 1/3
< 1/66/3, 5/2, 4/1, 3/1, 2/1 or darker
outside range of fibric or sapric material
Hemic (fibrist soil)1/3 to 2/3
> 2/3
> 1/6
< 2/5 & 3/4
7/1, 7/2, 8/1, 8/2, 8/3

Peatland (泥炭地)

Land covered with peat
= muskeg, moor, organic terrein
Soil saturation (土壌飽和): pores in soil completely filled with water
Soil drainage classes: describe file soil moisture conditions as determined by the capacity of the soil and the site for removing excess water. The classes range from very well drained, where excess water is removed very, quickly, to very poorly drained, where excess water is removed very slowly. Wetlands include all soils in the very poorly drained and poorly drained classes, and some soils in the somewhat poorly drained class
Temporarily wet soil (一時的湿性土壌): the soil close to the soil surface (i.e. within 40 cm) is occasionally wet for periods > 2 weeks during the wet season in most years. However, it is seldom flooded or saturated at the surface for longer than a month.

Use (利益)

containing 400 billion tons of carbon and cut down the amount of greenhouse gases
harvested, dried, and used as a fuel
harvested for use as a soil conditioner and plant packing material