ISHS Acta Horticulturae 779: International Symposium on Growing Media
MINERALIZATION/IMMOBILIZATION OF NITROGEN AND PHOSPHOROUS IN COMPOSTED GROWING MEDIA |
| Authors: | M. Contin, M. De Nobili, C. Cattivello |
| Keywords: | substrates, compost, nutrients availability, microbial biomass, temperature, moisture |
| DOI: | 10.17660/ActaHortic.2008.779.77 |
| Abstract:
The effects of different temperature and moisture regimes of a composted growing medium on N and P plant-availability and main differences with a peat-based growing medium have been evaluated during laboratory incubation experiments. The influence of root growth has also been tested by plant growth experiments. Microbial biomass and extractable N and P have been determined during a time-course incubation up to 56 days. The microbial biomass carbon (Bc) was relatively high in the composted growing media (2900–3600 µg Bc g-1) but less influenced by treatments. In contrast, Bc was much lower in peat-based growing media (350–600 µg Bc g-1) but more modified by the incubation conditions, especially by drying/rewetting cycles and by root growth. On the other hand, mineral N and extractable P were much less affected in the peat-based growing media than in the composted growing media. The cyclic changes of moisture regimes in particular, produced a much higher mineralization rate. In the composted growing media, small changes in soil microbial biomass were associated with larger changes in microbial activity. | |
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