THE USE OF COMPOSTED WOOD WASTE AS A PEAT SUBSTITUTE

Sawdusts of Eucalyptus and rewsii, E. micro corys, E. pilularis, E. radiata, E. saligna, mixed Eucalyptus species, Tristania conferta, Tsuga sp., bark of Pinus radiata and expanded hardwood chips were composted with 6.24 g N/Kg dry weight (except the bark – 2.63 g N/Kg dry weight) and a complete range of added nutrients.
Nitrogen immobilization by the softwood Tsuga sp. (4.34 g N/Kg over a 44 day period supplied as NH₄NO₃) was less than in the hardwood sawdusts (average 5.5 g N/Kg). All the wood wastes before composting exhibited phytotoxicity.
However by the end of the composting period there was no effect on the germination rate of cabbage (Grey-green Hybrid). Tomato (Grosse Lisse) were more sensitive to the toxins in the unstreamed wood waste.
Steaming the composted hardwood wood wastes decreased their phytotoxicity to tomatoes but increased the phytotoxicity of the softwood wood wastes.
Growth of Pilea cadierei cv.
Minima under a liquid fertilizer regime (125 ppm N 75 ppm, K,3 times per week was similar in composted and steamed hardwood waste and sphagnum peat.
However the growth rate of Pilea in composted and steamed softwood waste was significantly lower than in both.

Symposium on Production of Protected Crops in Peat and other Media

R.J. Worrall

https://doi.org/10.17660/ActaHortic.1978.82.10