THE USE OF CARBONIZED RICE HULLES AS AN HORTICULTURAL SUBSTRATE

Rice hulls are mentioned in the technical literature as an ingredient for potting media (POOLE & WATERS, 1977) or as an alternative substrate for soilless culture (NAMIOKA, 1977), Carbonized rice hulls have been used for several years by some commercial flower growers in Brazil as a substrate for rooting cuttings of roses and chrysanthemuns stocks.
Due its good drainage and high permeability this material is specially adequated to be used as rooting medium under intermitent mist.

Rice hulls are an easy available industrial residue (about 1,01 thousand tons/year) in Rio Grande do Sul, Brazil.
After the carbonization process rice hulls have a near neutral pH (7,5 in H₂O), in low bulk density (about 220 g/l), more than 50% dry matter, a high total porosity, with a air: water ratio near 3:1 at container capacity and a low volume of water in micropores (9% water held at 100 cm water tension).

The purpose of this study was to test mixtures of carbonized rice hulls and peat ("Aguas Claras", Viamão/RS-Brazil) as potting media.

II Symposium on Horticultural Substrates and their Analysis, XXIII IHC

A.N. Kämpf, M. Jung

https://doi.org/10.17660/ActaHortic.1991.294.29