Growth of Hedera helix L. container plants in compost substrates made withMiscanthus ogiformis Honda straw and various N-sources

Ammonium sulfate or urea were added as N-source to shredded straw of Miscan thus ogiformis 'Giganteus' and water was included as control. The combined materials were composted for seven months, and the resulting composts were tested as growth substrates for nursery container plants and compared with fertilized and unfertilized peat substrates. The pH was below recommended l evel for the Compost substrate made with ammonium sulfate and for the unfer tilized peat substrate throughout the experiment. Electrical conductivity a nd concentrations of most nutrients were low and decreased throughout the e xperiment for all growth substrates. Shrinking of the growth substrates aft er 4, 12 or 17 months was larger for compost substrates than for peat subst rates. Bulk density increased in compost substrates and decreased in peat s ubstrates, while the total loss of C was greater in compost substrates than in peat. Water retention was lower and air volume greater for compost subs trate made with ammonium sulfate than for fertilized peat. Algae and mosses did not occur on Miscanthus compost growth substrates in contrast to peat substrates. The shoot length and dry matter of Hedera helix, produced after four and 12 months of growth, and five months following cut back, showed t hat plants can grow well in compost substrates made of Miscanthus straw and ammonium sulfate or urea. However, the compost substrates could not fully substitute for fertilized or unfertilized peat substrate with respect to dr y matter production.