Leachate, Aerated Worm Tea and Vermicompost

My worm ‘hobby’ began in 1999 after attending a Master Gardner Composting class. My hobby continues to keep me fascinated by red wigglers and the work they do recycling my kitchen garbage. I have had successes and failure over the years; I have experimented, tested and watched my garden thrive. Two years ago I wanted to learn more so off I went to North Carolina State University’s annual Vermiculture Conference. The conference and people were so inspiring I went again in November 2012 to attend the 13th annual Vermicompost Conference in North Carolina. This is the only conference about earthworm farming and mid-to-large scale vermicomposting held in North America. We were 120 in attendance, people from 27 states and 5 countries gathered for 2 full days of learning and sharing Research based information. The conference is coordinated by Rhonda Sherman, an extension specialist in the Department of Biological and Agricultural Engineering at North Carolina State University. Yes this conference was for WORM People and Researchers from around the world giving us the hard facts based on scientific Research. One of the topics discussed was the differences between Vermicompost Tea and Leachate.

It all begins with red wigglers which are a smaller earthworm that lives near the top of the soil consuming organic matter. My choice of feedstock is all my kitchen garbage and disease free plant debris from my yard, and my goals are to create vermicompost and aerated compost tea. There are many commercial and homemade worm bins from small to large. The process is the same and the results are the same.

Aerated Compost Tea is produced during a 12-24 hour aeration cycle or putting your finished compost in a bucket for 3-7 days and stirring occasionally. The rationale for introducing air into the extraction process is to encourage the proliferation and survival of aerobic microorganisms in the water and also to decrease the culture and development of anaerobic microorganisms that may produce metabolic byproducts unfavorable to plant growth in the water extract. Vermicompost tea contains a large diversity of bacteria, fungi, protozoa and nematodes. It also helps increase soil biological activity, encourages positive effects in plant vigor, yield, bud break, fruiting, flowering, color, root volume, seed germination, pest and disease resistance. Vermicompost Tea can be used as a foliar spray or soil drench.

The message of leachate has not been a popular topic. Many worm composters are unfamiliar with the topic of aerated compost tea, preferring to use the leachate that many vermicompost systems encourage with their spigots. Although leachate seems to provide benefits to plants and vegetable gardening, it carries a very real risk to humans and plants.

Research shows that leachate should be discouraged. Vermicompost tea

is NOT leachate. The excess water dripping through a worm bin is considered leachate; it picks up undigested material which may contain pathogens and chemicals that are toxic to plants and humans. Professor Sherman says proper maintenance of a worm bin will not collect or seep excess water or leachate. Recommended use of leachate is to water your favorite weed or flush it down the toilet. The risk of using leachate on plants, especially the edibles, is not worth the risk of possible pathogenic contamination.

There is a difference between leachate and vermicompost which is produced in the presence of red wigglers in the worm bin. The worms and microbes gobble up the pathogens in their environment while eating the foodstock and do not release the pathogens back into the soil. Microbes are part of a worm bin ecosystem working and living amongst the worms in the vermicompost eating and overpopulating the pathogens while being ingested by the worms as well. The finished vermicompost is ready to use when you don’t recognize the original feed stock, it smells wonderfully clean, earthy and appears brown and crumbly.

During this discussion, I began to wonder if the pathogens the worms previously digested are freed upon worm death. Dr. Otto D Simmons III, Research Assistant Professor in Biological and Agricultural Engineering at North Carolina State University replied the “other worms digest the dead ones very quickly and the pathogens are eaten by the surviving worms”.

So why do I use Aerated compost tea? The answer lies in the biology, adding organic life to the soil, improving soil structure, water retention, root depth and growth. Vermicompost tea used as a foliar spray naturally helps protect the plant from pests and disease thus reducing the use of chemicals. I love the idea that my plants seem happier and stronger due to my kitchen garbage. Be sure to use non-chlorinated water when making tea or watering your worm bins. Those of you on well water don’t have to worry about chlorine. City dwellers can set a jug or bucket of water out for 24 hours to degas the chlorine. Rainwater collected in buckets is also a good alternative to chlorinated water.

This information was collected through continuing solid based Research rather than opinions or facts not supported by extensive Research. This information is available in the book Vermicomposting Technology: Earthworms, Organic Wastes, and Environmental Management. Published by CRC Press, copyright 2011.

I overhead a young father explain worms to his very young son,

“Worms = Happiness”.