Performances of new materials for peat substitution in horticulture

Peat is a reference material in horticulture growing media, but it is a slowly sustainable resource. Florentaise researches into innovative raw materials have resulted in the creation of Turbofiber^® (TF), a pine bark fiber obtained through a thermo-mechanical extrusion, and Woodpeat^® (WP), made out of wood fiber (Hortifiber^®) and cocopeat mixed together. Both are substitution materials to peat. The purpose of the conducted trials is to show whether peat can be totally replaced in growing media. First the physical properties of TF and WP were measured and compared to those of a fine white peat (MP). Then two culture trials were managed: on Viola for TF vs. MP and Petunia for WP vs. MP. Their duration was adapted to the type of plants: 10 and 8 weeks, respectively. The criteria measured were the fresh weight at the end of the trial and an esthetic criterion, that allows to classify plants relative to each other. Respectively for MP, TF, WP: aeration was 18.2, 13.0 and 38.0%; water retention: 75.0, 74.0 and 56.0%; water availability 37.5, 36.9 and 30.9%; porosity 93.2, 87.0 and 94.0%. For each culture test, produced biomasses were statistically equivalent regarding to control, and the note of the esthetic criterion was close to the maximum. In both trials plants were considered having good esthetic quality, and being eminently marketable. So these peat substitutes are candidate materials for horticultural production. They allow flexibility to growers in the way they manage crops, especially regarding irrigation.