Effect of Refertilization on Tree Growth in an Old Drainage Area

1989

15 S.

8 Abb., 7 Tab., 27 Lit. Ang.

Bandaufführung

9795

At the time of drainage (in the 1930s) the experimental area was partly a pine mire and partly an open mire. At the inventory the mean height of the tree stand varied between 6.8 m and 17.1 m. The effect of the basic fertilization with phosphorus and potassium started to weaken after about 15 years. The factorial NPK refertilization experiment showed that trees were suffering especially from a potassium shortage, but that during the first few years following refertilization also nitrogen fertilization increased growth to some extent. The effect of nitrogen fertilization dependet on the total nitrogen content of peat. Ascocalyx abietina drastically reduced the growth of trees on all the plots during two-three successive years (5-7 years from refertilization), after which the growth remained clearly under the pre-epidemic level. The growth increase (range during 1978-84 0.9-1.4 m3.ha-1.a-1) caused by potassium refertilization continued even during the epidemic, but the volume of badly damaged or killed trees was unaffected by refertilization. Nitrogen application somewhat slowed down the recovery of living trees.