Compost Extract vs. Compost Tea

Compost extract and compost tea are both valuable tools in organic growing, but they differ in their microbial populations and applications. Compost extract contains a lower number of microorganisms compared to compost tea. When you create compost extract, you essentially transfer the microorganisms from the surface of the compost into the water. For instance, if your compost has about 100,000 microorganisms, the goal is to extract that same number into the water, ready for use immediately.

In contrast, compost tea involves adding microbial foods to the mixture, allowing those initial microorganisms to multiply into millions or billions, making it ideal for foliar applications. Compost extract, on the other hand, is better suited for soil applications, providing a quick and effective way to enhance soil health.

How to Make Compost Extract

Making compost extract is straightforward and requires similar materials to compost tea, minus the microbial foods. Here’s how to do it:

1. Gather Materials: You will need a clean container, clean water, compost or vermicast, and a brew bag.

2. Prepare the Water: Fill the container with clean water, allowing it to sit for 24-48 hours to off-gas any chlorine or chloramines.

3. Fill the Brew Bag: Use varying ages of compost to ensure a diverse microbial community. The volume of compost needed varies based on the amount of extract you want to make:

- 5 gallons: 2-4 cups of compost

- 50 gallons: 1 gallon (16-18 cups)

- 100 gallons: less than 2 gallons (28-30 cups)

- 1,000 gallons: 6-8 gallons

4. Agitate and Extract: Place the brew bag in the water and agitate it thoroughly for 3-5 minutes. This helps break down larger clumps and maximizes surface area exposure. You can swirl, shake, or squeeze the compost to extract as many microorganisms as possible.

5. Filter the Extract: After agitating, run the extract through a filter to remove sediments, and it’s ready for use!

Tips and Tricks

Double the Microbial Population: To increase the number of microorganisms in your extract, consider filling your brew bag multiple times. After agitating the first batch, you can replace the compost with a new batch. However, be mindful that too much sediment can clog filters over time.

Benefits of Compost Extract

Compost extract offers several advantages over compost tea:

1. Immediate Use: You can use compost extract right away, making it ideal for situations where you need a biological inoculant quickly.

2. No Risk of Anaerobic Conditions: Since compost extract does not involve brewing for microbial reproduction, you don’t have to worry about it going anaerobic or reaching a peak population.

3. Longer Shelf Life: The lower microbial count in compost extract means it has a longer shelf life compared to compost tea. The oxygen isn’t depleted as quickly, allowing for better storage.

Uses for Compost Extract

Compost extract can be used for a variety of applications, including:

- Soil soaks for agricultural and landscape applications

- Seed soaks to enhance germination

- Hydroponics systems

- Irrigation needs

- Extending the life of cut flowers

- Sprouting and microgreens production

In summary, compost extract is a valuable addition to any organic growers toolkit. It’s made similarly to compost tea but without the added microbial foods and brewing process. This means you can use it immediately, and it’s particularly beneficial for soil applications.