Floriculture crops are mostly grown in lightweight potting substrates (Poole and Conover, 1979). These substrates are frequently composed of mixtures having sphagnum peatmoss combined with other materials such as vermiculite or perlite and formulated to achieve desirable physical and chemical properties. There are many different substrate formulations used for floriculture crops, and thus there is not a universal substrate formulation. Most research on potting substrate has focused on the manner in which different media compositions affect plant growth (Bunt, 1971; Fonteno, 1993).
Concerns of future availability, excessive environmental degradation, and higher prices have generated much interest in sphagnum peat alternatives (Barkham, 1993; Buckland, 1993; Robertson, 1993). Materials being evaluated include seaweed and biosolid composts (Vendrame and Moore, 2005), composted urban plant waste (Benito et al., 2005), spent mushroom compost (Szmidt and Chong, 1995), and vermicompost (VC) (Atiyeh et al., 2000, 2001; Handreck, 1986).
Vermicomposts are produced using earthworms (Eisenia foetida) to break down and stabilize organic wastes. During feeding, earthworms fragment the waste, increase microbial activity, and result in a composting or humification effect on waste material. The VC is obtained as the organic waste passes through the earthworm gut and is oxidized by associated microorganisms. VC, as a result of their fine particle size and structure, are being used as organic fertilizers, soil amendments, and potting substrate components. The specific physical and chemical characteristics of VC are dependent on the material consumed by the earthworms; however, VC from similar origins have similar characteristics (Tomati et al., 1990). Besides serving as a source of organic matter, VC increase moisture-holding capacity and provide nutrients (Atiyeh et al., 2001; Galli et al., 1990; Tomati et al., 1988).
Characterizations of changes in potting substrate properties that occur with the incorporation of VC are needed. This is especially true because VC can be produced from many different types of wastes. The objective of this research was to determine the differences in physical characteristics and available plant nutrient content of a commercial peat-based substrate amended with VC from two different agricultural sources and the potential suitability as a potting substrate.
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Benito, M., Masaguer, A., Antonio, R. & Moliner, A. 2005 Use of pruning waste compost as a component in soilless growing substrate Bioresour. Technol. 96 597 603
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