What Is Compost Tea?

Compost tea is a liquid extract made by steeping compost in water using a variety of preparation methods.

Compost Tea IS NOT:

• Plant tea — A water extract of fresh, uncomposted plant material. Comfrey is a common plant used.
• Manure tea — A water extract made using uncomposted animal manures. Human pathogens are a major concern. Manure teas should NEVER be used for crops grown for human consumption.

Two Primary Methods of Producing Compost Tea

• Aerated — Uses agitation or forced air aeration to maintain an oxygen-rich atmosphere during the brewing process.
• Non-aerated — Allows the tea to steep with no effort to maintain an oxygen-rich environment. The tea is produced in an anaerobic environment.

With each method, you can add additional materials to boost your tea or use as is when finished brewing.

• Some commonly used additives:
  • Molasses
  • Soluble kelp
  • Yeast
  • Humic acid
  • Fish hydrolysate
• Most compost teas are not approved by the Environmental Protection Agency (EPA) for use on edible crops. Minimally, this would require use of EPA-approved compost, approved agricultural water, and no post-brewing additives.
• Additives can increase the number and variety of both good and bad microorganisms in the compost tea.

Some Beneficial Claims Made for Compost Teas:

• Increases soil population and microbe diversity.
• Higher crop yields.
• Increased nutrient and nutrient availability.
• Use less fertilizer.
• Use less compost.
• Use less water.
• Disease control and suppression.
• Increased root growth and function.

Benefits with Scientific Research Substantiation.

• Disease control and suppression.
• A few studies have shown slight disease suppression under laboratory conditions.

Conclusions Regarding Compost Teas:

• Science and the compost tea industry disagree on the effects and benefits of compost tea.
• No scientific evidence for most beneficial claims regarding compost tea.
• No scientific evidence for the preferred use of compost tea over compost.
• Use of compost teas, in most instances, on commercial fruit and vegetable production is prohibited because of additives.
• Production and use of compost teas at home often carries the risk of human pathogens.
• Use of commercially prepared compost teas probably won’t hurt you or your plants.

Authors:

Joe Willis, Extension Agent, Orleans Parish; Achyut Adhikari, Associate Professor, School of Nutrition and Food Sciences; Christopher Dunaway, Assistant Extension Agent, Jefferson Parish; Bert Hammett, Extension Agent, East Baton Rouge Parish; Jeff Kuehny, Director, LSU AgCenter Botanic Gardens; Juan Moreira, Research Assistant, School of Nutrition and Food Sciences and Anna Timmerman, Assistant Extension Agent, St. Bernard Parish

Visit our website: www.LSUAgCenter.com

Pub. 3838-E (Online Only) 04/22

Luke Laborde, Interim LSU Vice President for Agriculture

Louisiana State University Agricultural Center, Louisiana Agricultural Experiment Station, Louisiana Cooperative Extension Service, LSU College of Agriculture

The LSU AgCenter and LSU provide equal opportunities in programs and employment.

Funding for this publication is provide by the USDA NIFA FSOP Award #: 2020‐70020‐33035