Earthworm castings as a substrate for poinsettia production
2002
Hidalgo, P.R. | Harkess, R.L.
Experiments were conducted to evaluate earthworm castings (vermicompost) as a substrate for poinsettia (Euphorbia pulcherrima Willd.) 'Freedom Red' production. Vermicomposts produced from sheep, cattle, or horse manures were mixed at different ratios with 70 peatmoss:30 perlite (v/v) to create 13 substrates. Chemical and physical properties were measured on all substrates used. Growth index, foliar and bract area, and dry weight were greater on plants grown in substrates with castings from sheep or cattle manure. These castings had greater initial nutrient content than the castings from horse manure. Mixtures of castings and peat produced better plant responses than castings alone. Better plant responses were sometimes associated with values outside the recommended pH and electrical conductivity levels for poinsettia production. The highest values obtained for growth index, foliar and bract area, dry weight, and root development were produced in the substrates with moderate pore space or water holding capacity. Substrates with greater air space produced plants with greater dry weight and root development than substrates with less air space. The highest quality plants were grown in substrates with 25% castings from sheep or cattle manures.
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