Growth of Three Bedding Plant Species in Soilless Mixes With Alkaline Stabilized Sewage Sludge

Abstract

Abstract Three bedding plant species (‘Cooler Grape’ Vinca (Vinca rosea L.), ‘Roc Mix’ Pansy (Viola × Wittrochiana Gams.), and ‘Impulse Red’ Impatiens (Impatiens Wallerana Hook.f.) were grown in soilless mixes: aged N-Viro Soil from the City of Toledo, OH, aged N-Viro Soil blended with sphagnum peat (N-Viro Soilipeat, 3:1 by vol), BioBlend (composted leaf yard waste: N-Viro Soil, 2:1 by vol), and Sunshine Mix LC1. The N-Viro Soil-based media were high in pH (8.3–8.9), soluble salts (3.2–9.6 dS/m) and exchangeable Ca, Mg and K, compared to Sunshine mix. Total porosity was lower in the N-Viro Soil media (62 to 74%) compared to Sunshine (90%), while available water holding capacities were higher in Sunshine mix and N-Viro Soil-peat (7.4 and 7.6% H2O by volume, respectively) than in aged N-Viro Soil and BioBlend (5.4 and 5.9% H2O by volume, respectively). Differences among the media in growth index of impatiens were significant (p = 0.054). This reflected the low index for aged N-Viro Soil compared to the other three media. Pansy growth index differences among the media were significant (p = 0.031), with the aged N-Viro Soil and BioBlend indices being significantly lower than that of Sunshine mix. There were no significant differences in vinca growth index. There were no significant differences in top growth weights among the four soil media for all three species. The results suggest that aged N-Viro Soil can be blended with peat or fresh N-Viro Soil can be composted with yard waste to produce soilless plant growth media that are comparable in performance to commercial peat-based mixes.