NCSU Vermiculture Conference topic: The Utilization of Vermicomposts in Horticulture

Speaker: Norman Q. Arancon, PhD, Associate Professor, Department of Horticulture, University of Hawaii, Hilo

Much of today’s talk will build on chapters 9 and 10 of book available at this conference: Vermiculture Technology: Earthworms, Organic Wastes, and Environmental Management edited by Clive Edwards, Norman Arancon, & Rhonda Sherman. He started thanking Rhonda Sherman for organizing the conference every year. Here are my takeaways from his talk:

The real goal in vermicomposting is to make plants grow, so understanding the soil created is important. Soil is made up of 5% organic matter including microbial populations. Microbes cause decomposition, nutrient release, pest suppression, disease suppression, plant growth regulation, and soil aggregation. The other 95% of soil is also made up of air, water and mineral particles.

Popular farming methods — burning and pest control — kill important microorganisms.

Vermicomposts are stabilized organic matter produced by the interaction of worms and microorganisms under controlled conditions. With vermicomposting you can produce soil in a very short period of time — 60 days. Vermicompost has lots of surface area for nutients and moisture. It has plant-available nutrients, growth hormones and humic acids.

Results of using vermicomposts: accelerated germination of seeds, increased growth of seedlings, early flowering of plants, increased yields of plants.

    Optimimum rate of plant growth with 10 – 50% worm compost in growing mix. Over 60% decreased growth or even plant death from too much growth hormone. Results are in the shape of a bell curve.

    Rhizome growth — stem cuttings best growth in 20-60% vermicompost.

    Increased plant yield from 10 – 40% vermicompost in soil.

Reasons behind increased growth in plants: nutrition, plant growth hormones, humic acids

Plant growth hormones effective at very low concentrations. Different hormones affect different aspects of plant growth and development. Three of the growth hormones are found in vermicomposts — they are produced by microorganisms in vermicomposts.

Humic acids – organic polymers that can be extracted from humus. They “grab and protect” hormones and act like hormones.

How about vermicompost in a field instead of the greenhouse? Most yields of vermicompost-enhanced fields at 5-10 tons per hectacre outpaced regular inorganic fertilizer no matter how the compost was created (paper waste, cow manure, kitchen scraps).

Vermicompost and suppression of plant diseases: Pythium, Powdery Mildew and other diseases suppressed by probiotics in vermicomposts

Vermicompost and suppression of plant parasites and pests: numbers parasitic nematodes, cabbage caterpillars, aphids, mealy bugs, and other bugs reduced. In general great results with 20-40% worm compost in the growing medium. Why are the plants more resistant? They plants seem to be taking up phenolics from vermicomposts and producing metabolites which are unpalatable to insects.

Tomorrow Norman Arancon will present research on the effects of vermicompost extracts applied to the foliage of plants.

The reference text sold at the conference with articles by Arancon and other researchers in the field, Vermiculture Technology: Earthworms, Organic Wastes, and Environmental Management, is available on in hardcover and for Kindle.

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