Compost tea, a brewed nutritional extract for plants derived from compost, is often mistaken for leachate, the liquid expelled during the compost process. However, compost tea and leachate contain different microorganisms and may have very different results when used as a supplement. Leachate is not recommended for direct application without amendments, while compost tea, once brewed properly can safely be applied directly to soils and plants.
According to Steve Renquist, Horticulture Agent at Oregon State University, compost tea:
1. Increases the species diversity and biomass of microbes
2. Increases the number of beneficial predator organisms
3. Increases the ability of soil to retain water and hold nutrients
4. Reduces need for fertilizers and subsequent leaching into ground-water
5. Reduces the accumulation of salts in the soil
6. Provides microbe diversity to improve soil pH buffering ability
Dr. Elaine Ingham, of the Soil Food Web Institute, adds “Chemical-based pesticides, fumigants, herbicides and many synthetic fertilizers kill a range of the beneficial microorganisms that encourage plant growth, while compost teas improve the life in the soil and on plant surfaces. ”
Variables that have a high impact on the production of compost tea include;
Researchers at the University of Arizona, College of Agriculture & Life Sciences point out the importance of following proper brewing techniques when formulating compost tea,
"Though the composting process is adequate for destroying most pathogens, deviation from this process (such as addition of water and supplements during the brewing process, which could result in decreased temperatures in the compost), could result in the survival of pathogens commonly found in animal feces, including Salmonella, Listeria, and Escherichia coli, all of which are able to proliferate in soil with viability of up to 20 years"
Learn more about compost tea and the importance of proper processing and application.
Compost Tea Made Easy
Harvard University: Make Your Own Compost Tea
Effect of Aerated Compost Tea on the Growth Promotion of Lettuce, Soybean, and Sweet Corn in Organic Cultivation
Characters of compost teas from different sources and their suppressive effect on fungal phytopathogens
Compost Tea to Suppress Plant Disease
Effect of Molasses on Regrowth of E. Coli 0157:H7 and Salmonella in Compost Teas
ATTRA Sustainable Agriculture: Notes on Compost Teas
Video created by Paul Taylor
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