Compost Teas: Brewing a Sweet Blend
By: Kelly SlocumPosted On: Tuesday, 10 April 2001, in issue #27 of Worm Digest
A nice cup of good, hot tea has for years been enjoyed as a restorative to the mind and body. Centuries ago human kind learned that the flavor and beneficial essence of certain plants could be drawn from their leaves, bark and roots by steeping them in water, sometimes fortifying the brew with a bit of milk and honey.
How well we understand that a nip of soothing
mint tea will settle the stomach, a cup of fragrant chamomile tea will
soothe frayed nerves, and a heavy mug of vitamin rich alfalfa tea can
stimulate a weak appetite. By steeping these plant materials in water
we can partake of what is best about them when eating the plant is not
an option. This concept of using water to draw beneficial extracts from
solid materials for the purpose of making a liquid solution has applications
beyond making we humans feel better, however. Our plants and even our
soils can benefit greatly from a nice cup of tea when that tea is derived
from a plant nutrition source like worm castings. Understanding the Value of Castings [worm poop]
Castings added to the soil carry to the root zone a rich compliment of soluble plant nutrients and growth enhancing compounds, a diverse and populous consortium of microbial life and a substrate of organic matter harboring a storehouse of nutrients that are not lost to rain and irrigation. The plant is delivered an ongoing, reliable food source when bacteria and microscopic fungi feed on the organic matter, releasing some of the nutrients to the soil and storing others for their own energy and reproduction. When nematodes and protozoa in turn feed upon them, the nutrients stored in the bacterial and fungal bodies are released to the soil in a plant-available form.
Further, unlike soluble plant fertilizers, the nutrients stored in organic matter and the bodies of the microbial life are not lost through irrigation to contaminate ground water. When we add castings and the microbial life they support to the soil, we aid in increasing the complexity and diversity of organisms in the root zone, thus aiding in disease and pest suppression.
From Castings to Tea
So, “why tea?” one may wonder. With compost and worm products demonstrating such tremendous benefit to soil and plant life, why take the extra steps to generate a liquid from this already understood and easily applied solid material?
Leaf surfaces, like plant roots, harbor a rich microbial population that protects the leaf, and thus the plant, from infection and attack by pathogenic organisms. When the microbial consortium present on the leaf surface is reduced by pesticide use or environmental damage, it exposes leaf surface, opening infection points. We can reinoculate the leaf with the diverse communities of microbial life found in compost and worm castings by applying a tea made from these materials. Further, teas can be applied as soil drenches and root washes after pesticide use, to reintroduce to the soil microbial communities that may have been damaged by the pesticide. The microbes can then continue to provide protection from pathogens to the plant as well as aiding in breakdown of any pesticide residues in the soil, thereby preventing ground water contamination. Teas also carry the soluble nutrients and beneficial growth regulators contained in the solid matter used to make the tea. Many of these compounds can be absorbed through the leaf surface, feeding and enriching the plant.
Steeping the finished, stable end product of a composting or vermicomposting system in agitated, aerated water, then adding a nutrient mix for microbial growth makes a true tea. The water is agitated to extract as many of the organisms clinging to the solid matter as possible, and the nutrient mix provides those microbes dislodged into the liquid with a food source on which to grow and reproduce. Aerating the water ensures that it is the aerobic organisms that are supported in the liquid.
This blend of food and oxygen in the tea enables the microorganisms to grow to numbers rivaling those found in the solid matter from which the tea is derived. Teas must then be used within a few hours of being generated in order to ensure aerobicity and high microbial populations. Once the oxygen and food are consumed, anaerobic organisms will begin to populate the system, producing alcohols and phenols toxic to plants.
Good tea begins with good, quality compost, worm castings or vermicompost, or a blend of these materials. Provided the solid material is stable and supports sufficient beneficial microbial life, there is nothing in these liquids to cause plant damage.
Using the tea
Compost and castings teas are a relatively new product in today’s agriculture and gardening industries. Researchers are still identifying uses, though there is considerable research demonstrating that teas can suppress fungal disease in a variety of plant species and aid in disease prevention on plants where disease pressure is great.
Application rates for tea will vary considerably with the type of plant being treated, climate, and whether or not the plant is already battling a pest or infection. Dr. Ingham suggests that in agricultural fields the application rate begin at five gallons of undiluted tea per acre per week and adjusted as needed based on performance. For home use, teas can be applied to flowers, perennials, turf, roses, shrubs, trees and vegetables.
What we do not know about teas still far outweighs what we do know, though research demonstrates an exciting future for tea use. The possibility of finding a means of controlling certain plant diseases with a truly effective yet benign material that simply capitalizes on nature’s own means of control is a basic precept of sustainability and promises to help us repair the damage already caused by conventional agriculture techniques.
And while we may not know everything there is to know about tea, we know that using it harms nothing and very often brings great benefits. Indeed, there’s nothing like a good cup of tea!