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.
Atiyeh, R.M., Edwards, C.A., Subler, S. & Metzger, J.D. 2001 Pig manure vermicompost as a component of a horticultural bedding plant medium: Effects on physiochemical properties and plant growth Bioresour. Technol. 78 11 20
Atiyeh, R.M., Subler, S., Edwards, C.A., Bachman, G., Metzger, J.D. & Shuster, W. 2000 Effects of vermicomposts and composts on plant growth in horticultural container substrate and soil Pedobiologia (Jena) 44 579 590
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
Berghage, R.D., Krauskpf, D.M., Warnke, D.D. & Widders, I. 1987 Micronutrient testing of plant growth substrate: Extractant identification and evaluation Commun. Soil Sci. Plant Anal. 18 1089 1109
Bilderback, T.E., Fonteno, W.C. & Johnson, D.R. 1981 Physical properties of substrate composed of peanut hull, pine bark, and peatmoss and their effects on azalea growth J. Amer. Soc. Hort. Sci. 107 522 525
Buckland, P. 1993 Peatland archeology: A conservation resource on the edge of extinction Biodivers. Conserv. 2 513 527
Fonteno, W.C. 1993 Problems and considerations in determining physical properties of horticultural substrates Acta Hort. 342 197 204
Gabriels, R., Van Keirbuick, W. & Engels, H. 1993 A rapid method for determination of physical properties of growing substrate Acta Hort. 342 243 247
Galli, E., Tomati, U., Grappelli, A. & Di Lena, G. 1990 Effect of earthworm casts on protein synthesis in Agaricus-bisporus Biol. Fertil. Soils 9 290 291
Sharpley, A.N. & Syers, J.K. 1976 Potential role of earthworm casts for the phosphorus enrichment of run-off waters Soil Biol. Biochem. 8 341 346
Spomer, A.L. 1975 Small soils containers as experimental tools: Soil water relations Commun. Soil Sci. Plant Anal. 6 21 26
Szmidt, R.A. & Chong, C. 1995 Uniformity of spent mushroom substrate (SMS) and factors in applying recommendations for use Compost Sci. Util. 3 64 71
Tilt, K.E., Bilderback, T.E. & Fonteno, W.C. 1987 Particle size and container size effects on growth of three ornamental species J. Amer. Soc. Hort. Sci. 112 981 984
Tiwari, S.C., Tiwari, B.K. & Mishra, R.R. 1989 Microbial populations, enzymes activities and nitrogen-phosphorus-potassium enrichment in earthworm casts and in surrounding soil of a pineapple plantation Biol. Fertil. Soils 8 178 182
Tomati, U., Galli, E., Grappelli, A. & Di Lena, G. 1990 Effect of earthworm casts on protein synthesis in radish (Raphanus sativum) and lettuce (Lactuca sativa) seedlings Biol. Fertil. Soils 9 288 289
Vendrame, W. & Moore, K. 2005 Comparison of herbaceous perennial plant growth in seaweed compost and biosolids compost Compost Sci. Util. 13 122 126
Yeager, T.H., Wright, R.D. & Donohue, S.J. 1983 Comparison of pour-through and saturated pine bark extract N, P, K, and pH levels J. Amer. Soc. Hort. Sci. 108 112 114