NITROGEN DYNAMICS IN BARK COMPOST AS DEPENDENT ON PRODUCTION METHODS – I. MODEL TRIALS

In model trials without plants (25° C, 90 % of water holding capacity), the change of soluble (0.025 N CaCl₂) mineral N (NO₃, NH₄) in bark composts was studied for 17 weeks without and with N-application (80 mg N as NH₄NO₃/20 g compost dry matter). 8 bark composts, produced by different fermentation procedures, were compared with sphagnum peat:

4 long-term composts ± N-application for fermentation

3 short-term composts + N-application for fermentation

1 bark compost from a depot (about 25 years old) – N-application

The amounts of C_t varied between 27 and 42 %, N_t between 0.66 and 1.16 % i.dry matter.

Long-term fermented bark composts showed nearly a constant supply of soluble N during the first 10 weeks; lateron the amounts of N_min decreased slowly similar to peat (N-fixation). The depot-bark strongly fixed fertilizer-NH₄ (C/N = 47). Short-term composts were very variable in N_min -contents (N-fixation and remineralization).

The great differences in nitrification capacity of tested bark composts were independent of method of fermentation respectively pH of compost (pH 5.2–7.6); this may be mainly explained by different degrees of pollution with soil.

International Symposium on Substrates in Horticulture other than Soils In Situ

R. Gutser, K. Teicher, P. Fischer

https://doi.org/10.17660/ActaHortic.1984.150.19