NITROGEN AVAILABILITY IN COMPOSTED CORK

Previous studies showed that plants grown in fresh cork (Quercus suber L. bark) had a reduced growth compared with peat and low rates of N. In composted cork, however, plant growth was similar with those in peat, but the N content of plants was still slightly lower.

The purpose of this study was to investigate N availability in fresh and composted cork during 4, 5.5 and 7 months, using peat as control medium.
The substrates were also incubated at 25°C during 60 days after adding 0.25, 1.0, 1.75 or 3.0 g ammonium nitrate per 1 of substrate.
Samples were taken periodically to measure NO₃-N, NH₄-N and total N. Also the Nitrogen Drawdown Index (NDI) for the addition of 75 mg.1^-1 N and 150 mg.l^-1 N was measured after incubation at 25°C.

N immobilization rates were well correlated to NDI. NH and soluble N drawed down rapidly in cork substrates while total N stayed constant.
High rates of ammonium nitrate should be added to maintain a constant level of available N to plants in cork.

International Symposium Growing Media and Plant Nutrition in Horticulture

E. Carmona, J. Ordovás, M.C. Ortega, M.T. Aguado

Bark, growing media, N immobilization

https://doi.org/10.17660/ActaHortic.1997.450.42