Suo - Mires and peat vol. 48 no. 2 | 1997
Turpeen puristenesteen sähkönjohtavuuden riippuvuus vesipitoisuudesta.
English title: Relationship between electrical conductivity and water content in peat growth medium.
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The relationship between electrical conductivity (EC) of press-water extract and water content (WC) of peat growth medium at desorption was studied. A simple time-domain reflectometer (TDR), traditional laboratory conductivity meter and gravimetric weighing were used to measure EC and WC. The relationship between EC values measured with a laboratory conductivity meter from press-water extract and those measured with TDR directly from peat medium was curvilinear. The relationship between WC of peat measured with TDR and that determined gravimetrically, although nearly linear, was slightly sigmoidal. Empirical curve between EC values and WC values measured with TDR was close to the theoretical curve, which was calculated on the basis of increase in ion concentration at desorption. Transformed EC values of press-water extract were higher than the theoretically calculated values. For comparison of EC values measured from press-water extracts in various water contents, transforming coefficients were derived.
Key words: nutrient monitoring, fertilization, TDR
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Rikala,
The Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland
Sähköposti:
ei.tietoa@nn.oo
- Heiskanen, Sähköposti: ei.tietoa@nn.oo
Metsitettyjen turvepeltojen ja viereisten suometsien ravinnemäärät.
English title: Nutrient amounts of afforested peat fields and neighbouring peatland forests.
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Chemical and physical characteristics of afforested peat fields were compared with those of neighbouring peatland forests, i.e. naturally forested peatland sites drained to improve forest growth. Six study sites were selected with such sites located alongside an afforested peat field. On three of the fields, mineral soil had been added during cultivation as a soil amelioration agent. Most of the fields had been cultivated for 15–20 years before afforestation. Volumetric soil samples were taken and analysed for their total and ammonium acetate extractable nutrient concentrations (P, K, Ca, Mg, Mn, Fe, Zn). Kjeldahl N and B in H3PO4–H2SO4 were also analysed. The soil layers 0–20 cm (the field cultivation depth) and 20–40 cm were compared. The physical and chemical characteristics of the top soil in peat fields and neighbouring forests differed in many respects even after 25 years had passed since their afforestation. Bulk density, ash content and pH of the peat were higher in the cultivation layer of the fields than in the corresponding layer in peatland forests. In cases where mineral soil had been added to the peat fields, the amounts of P, K, Ca, Mn and Zn were higher in the 0–20 cm soil layer whereas the amounts of N and B did not significantly differ from those in the soils of peatland forests. The differences in the amounts of extractable nutrients between the field soils and forests soils were smaller; Ca and (when mineral soil had been added) also Fe and Zn concentrations were higher in the peat field soils than in the soils of peatland forests.
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Hytönen,
The Finnish Forest Research Institute, Kannus Research Station, P.O.Box 44, FIN-69101 Kannus, Finland
Sähköposti:
ei.tietoa@nn.oo
- Wall, Sähköposti: ei.tietoa@nn.oo
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