ISHS Acta Horticulturae 150: International Symposium on Substrates in Horticulture other than Soils In Situ
NITROGEN BALANCE IN BARK COMPOSTS USED AS GROWING MEDIA |
| Authors: | A.R. Selmer-Olsen, M.D. Sant, H.R. Gislerød, K. Solbraa |
| Abstract:
Composted bark samples of spruce (Pica abies), pine (Pinus sylvestris), hardwood (mostly Betula pubescens), mixtures of spruce and hardwood, composted pine bark from Spain and sphagnum peat moss were used in pot experiments with lettuce (cv. Ostinata) and chrysanthemums (cv. White Horim). The plants were grown in mixtures of 2/3 bark compost and 1/3 peat. They were fertilized with known amounts of nitrogen. Inorganic nitrogen as well as Kjeldahl N was determined in the growing media both at the start and the end of the experiments. When the yield and the amount of nitrogen in the plants is known a nitrogen balance might be found. Lettuce grown in peat utilized the greatest amount (62–40 %) of total inorganic nitrogen, depending on N-fertilization. Plants in hardwood bark utilized 50–36 %, while plants in spruce bark utilized only 29–27 %. The analytical results also made it possible to calculate the loss of inorganic nitrogen during the growing period. This loss, compared to the available amounts of inorganic nitrogen when lettuce was grown, was greatest for spruce and the mixture of spruce/hardwood 80/20 (60–70 %). Most of this loss may be explained by the escape of gaseous N-compounds. | |
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