Maintenance of sustainable nutrient status in peatland stands

Fertilisation increases the growth of peatland stands

The growth of nutrient-poor drained peatland areas can be improved with phosphorium-potassium-boron (PPB) fertilisation for as long as 20 to 30 years. The most noticeable increases in growth were gained in thick-peated nitrogen-rich mires, where the growth response was 2 to 3 times the growth observed in non-fertilised stands. When refertilisation was performed after 10-20 years, the effect on stand growth was clearly less than that of the first fertilisation. On sites with limited potassium availability, however, the added potassium increased stand growth substantially. It seems that refertilisation in nutrient-deficient areas is necessary only once or twice during the rotation period. Iron, when added to the fertiliser, prevented phosphorium leaching effectively, but at first the addition also slowed down the fertilisation effect on the stand.

The results suggest that the nutrient status of a coniferous tree can be determined accurately with needle samples collected in winter or early autumn. Peat analysis proved also to be a relatively good indicator of nutrient status in peatland stands.

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