Jouko Silvola

Ojituksen ja lannoituksen vaikutus turpeen hiilen vapautumiseen ja ravinteiden mineralisoitumiseen

Silvola J. Ojituksen ja lannoituksen vaikutus turpeen hiilen vapautumiseen ja ravinteiden mineralisoitumiseen.

Tiivistelmä

Carbon dioxide production increased to 2-3 fold from the peat of an oligotrophic sedge pine mire (VSR) after draining had lowered the water table to a depth c, 0.5 m. At two other sites, a mesotrophic sedge pine mire (RhSR) and a spruce swamp (MK), both the fall in the groundwater table and the increase in C02 production were smaller. At the VSR site, the fast-dissolving PK fertilizer and urea each caused a rapid increase while the slow-dissolving PK fertilizer a slow increase in soil respiration. The greatest, steady increase was achieved by treatment with wood ash. At RhSR and MK sites, the use of fertilizers generally led to a decline in soil respiration for 1-2 years, after which the initial level was normally regained. According to a simulation of the C02 production after drainage, the annual decomposition of peat was calculated to be c. 1 000 g (organic matter) m-2 in the VSR site. On the basis of this decomposition rate, the annual amount of nitrogen mineralizated was estimated to be c. 100 kg ha-1 and that of phosphorus c. 5 kg ha-1. Peat contains only a small amount of potassium, and the decomposition of old peat layers increases the amount of soluble potassium in peat very little. Keywords: Carbon balance, drainage, fertilization, nutrient mineralization, peat decomposition

Avainsanat
fertilization; Drainage; Carbon balance; nutrient mineralization; peat decomposition

Vastaanotettu 31.10.2017 Julkaistu 1.1.1988

Katselukerrat 2192

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