Pro and Cons About Composting Tea

Compost has long been known to improve plant health by adding helpful fungi, insects, bacteria and nutrients to the soil. You can also put the powerful benefits of compost to use by diluting it to make a compost "tea" and applying it to plants. Although compost tea can benefit your garden, there are risks and controversies to be aware of.

Compost tea is an organic liquid intended to improve the health of plants and soil. It is made from high-quality compost containing plant compounds, animal manure and helpful microorganisms. It is made by placing it in a burlap sack and putting the sack inside a large barrel of water to create a nutrient-rich liquid. It can be amended with other nutrient sources like kelp, fish byproducts or humic acid to add beneficial microbes. Compost tea may be aerated or non-aerated. In a non-aerated process, compost is mixed with water and other ingredients and allowed to ferment on its own. In an aerated process, air is injected into the mixture to potentially increase oxygen levels and the growth of aerobic microorganisms. Compost tea is applied to leaves using a sprayer system or to the plant's root zone by watering the soil directly.

Compost tea nourishes the soil, improves plant growth and fights pathogens that can harm plants. A study by Pennsylvania State University showed that aerated compost tea decreased powdery mildew and gray mold and improved crop yield and growth. Compost tea can also suppress diseases such as Anthracnose, wilt, clubroot, damping off disease and southern blight. It does not necessarily fight disease in all plants, and its major benefits are its ability to improve plant yield, growth and quality.

Because each batch of compost tea is different depending on its base ingredients, it is difficult to conclusively determine whether the tea is effective in fighting diseases and improving plant health. Compost tea may not be reliable on all crops and can be harmful. The Pennsylvania State University study showed that compost tea actually increased downy mildew disease in certain crops and did not affect potato blight at all. Other potential downfalls of compost tea are pollution and dangerous bacteria. If tea is over-applied, nitrogen, phosphorous and other nutrients can pollute nearby water sources, harming aquatic life. The U.S. Department of Agriculture also discourages growers from using compost tea for foods that will be eaten raw, as Escherichia coli and other dangerous pathogens could infect humans.

Certain practices can improve compost tea's effectiveness. Use high-quality compost from horse, cattle or poultry manure that is less than 1 year old. During brewing, keep it out of sunlight. Allow it to ferment for a minimum of five to eight days if you are not aerating it. If aerating, allow tea to ferment 24 to 48 hours. Use compost tea within four to six hours after brewing and brew a new batch for each application, as beneficial bacteria die off quickly. Use compost tea as part of a comprehensive garden health plan and consider safety by using clean water, sanitizing equipment before each use, and heating compost to at least 131 degrees Fahrenheit for three days before using it for tea. Wash your hands thoroughly after working with compost or compost tea.