ISHS Acta Horticulturae 172: Composts as Horticultural Substrates
WOODWASTE COMPOSTS AS GROWING MEDIA FOR VEGETABLES UNDER PROTECTION |
| Author: | T. Pudelski |
| Abstract:
The paper discusses industrially produced pine and common beech bark composts used in different methods of growing vegetables under protection in Poland. The usefulness of bark composts produced locally by vegetable growers has been demonstrated. The utilization of the initial composting phase, i.e. hot fermentation, is essential for growing vegatables under protection, the compost being a substrate heating agent in stenothermal vegetable production. The use of such biologically heating layers results also in a lasting carbon - dioxide enrichment of the greenhouse atmosphere and counteracts significant drops in CO2 level due to intensive photosynthesis in the summer months. The utilization of woodwastes for vegetables under protection was initiated in Poland in the mid 1960's. Fresh pine bark was used as an additive to black peat, 30 to 50% by volume, in order to improve the physical properties of this growing medium in its long term use for cucumber growing under glass. A method of composting coniferous tree bark was developed in the late 1960's in the Forest Research Intitute in Warsaw, somewhat later also a method of composting common beech bark. The what later also a method of composting common beech bark. The method involves addition of urea, 3 kg per 1 m3, and 10 to 15% by volume of biologically active sediment from waste purification plants of paper mills. Composting takes place in piles of 6 m width and 2 m height over a period of 4 to 6 months. In this time, the compost piles are inverted several times /Ostalski, 1974/. Pine bark composts, with an addition of up to 10% of birch bark, are produced industrially in paper mills in Swiecie and Ostroleka since 1970. The Swiecie paper mill also produces common beech bark compost. Bark composts are accepted for distribution when the content of ammonium and nitrate forms of nitrogen does not exceed 300 mg/dm3. Such relatively fresh bark composts cannot be used as exclusive substrates, but have a high fertilizing value. After another 4 to 6 months of storage the level of both mineral nitrogen forms drops to several dozen mg/dm3. The following guidelines should be kept in mind when using industrial coniferous tree bark composts for substrate preparation: 1/ two to three weeks prior to substrate preparation the compost pH as well as its salinity and content of both nitrogen forms should be determined by means of methods commonly used in chemical laboratories in Poland and described in detail by Nowosielski, 1972. | |
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