Jennifer Martin, (202) 720-8188
By Stacy Kish
August 10, 2009
Lots of folks fancy a cup of tea when they need a pick-me-up – orange pekoe, Darjeeling, etc. Not surprisingly, a spot of tea can help plants feel better, too. But not just any tea; if you want to share a pot with your plants, you’ll need to brew up some earthworm tea.
This beverage, which has become all the rage in organic agriculture, is not made from earthworms. No, this tea is made from earthworm excrement steeped in liquid. Earthworm tea is easier to transport and apply to crops than other types of fertilizers, and plants love it.
With funding from USDA’s Small Business Innovation Research (SBIR) program, administered by the Cooperative State Research, Education, and Extension Service (CSREES), scientists in Oregon and Ohio examined how plant compounds, incorporated into earthworm tea, affect plant growth and development and suppress diseases and pests.
Soil is a medium that supports plants and stores the nutrients necessary for plant growth and development, but the choice of soil makes a substantial difference to how plants thrive. Earthworms and microbes play an important role in improving soil fertility.
Vermicompost, the end product of an earthworm meal, not only dramatically increases plant growth and yield, but also suppresses diseases, parasitic nematodes, and arthropod pests. Vermicompost maintains high levels of microbial activity, which produces such valuable plant compounds as growth hormones, plant growth regulators, and soluble nutrients.
These compounds normally break down quite rapidly in soils, but they stick to the humic acid produced during the vermiculture process. Like a time-release capsule, the chemicals release slowly to promote enhanced plant growth and production.
Keith Fletcher and colleagues at Oregon Soil Corporation, in conjunction with Clive Edwards of The Ohio State University, tested food-waste teas on the growth of tomato and cucumber plants.
“The vermicompost tea increased plant growth and yields dramatically—by up to 50 percent,” Edwards said.
In addition, the teas successfully suppressed pests and diseases and limited the damage caused by plant pathogens, parasitic nematodes, aphids, and spider mites.
Most importantly, the tea produced the favorable environmental soil conditions required for healthy microbial activity, made nitrogen available to the plants, and provided plant growth promoters.
Organic gardeners, growers, and farmers are always looking for non-chemical methods to suppress plant pathogens and pests. “The benefit of increasing crop production is an added bonus. The ease of use of vermicompost teas is particularly attractive to organic growers,” Edwards said.
The use of vermicompost and vermicompost tea reduces the application of synthetic fertilizers and pesticides onto farmland with little or no impact to soil and water quality or to the surrounding lands.
Future work will focus on the shelf life of vermicompost teas to ensure the highest quality product for commercial application and its use on other crops.
CSREES funded project with SBIR Phase I and Phase II funds. Through federal funding and leadership for research, education and extension programs, CSREES focuses on investing in science and solving critical issues impacting people’s daily lives and the nation’s future. For more information, visit www.csrees.usda.gov.