Leila Urvas

Etelä- ja Pohjois-Suomen luonnontilaisten turpeiden viljavuuserot

Urvas L. Etelä- ja Pohjois-Suomen luonnontilaisten turpeiden viljavuuserot.

Tiivistelmä

Due to climatic differences, vegetational variation occurs even within the same mire types from southern to northern parts of Finland. Accordingly, geographical differences in fertility can be expected. This material was collected from 338 sites in South Finland and 468 sites in North Finland during the 1960s (Fig. 1). When sampling virgin peat soils in routine soil survey work, three samples were collected from each site; depths 0—20, 20—40 and 40—60 cm. The pH (H2O) and acid ammonium acetate extractable Ca, K, and P were determined from all samples. In addition, N and humus percentages were determined from surface soil samples. The average pH (H2O) in different layers of Carex dominated peat soils was 0,1— 0,4 pH-units lower in South than in North Finland and the corresponding differences in Sphagnum dominated peat soils were 0,2—0,3 pH-units (Table 2). Average contents of ammonium acetate extractable potassium and especially calcium and phosphorus were higher in South than in North Finland. One reason for higher soluble nutrient contents in the South may be the lower pH in southern peat soils. Also the mineral subsoil underlaying the peat may have an effect on the fertility properties of the peats. In general, northern mineral soils are coarser in texture and poorer in nutrients than those in the South. The total nitrogen contents of Carex dominated peat soils were 21 per cent higher in northern than in southern peat soils and those of Sphagnum dominated peat soils 17 per cent higher. This may be partly due to the fact that within both peat types (Carex and Sphagnum) the composition of plant species responsible for peat formation varies from south to north. According to the differences in nitrogen contents, the C/N ratios, an index indicating the quality of peat, were smaller in the northern peat soils.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1980

Katselukerrat 394

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