Photo above: Building an aeration system for making compost tea takes just a few minutes.

Make this biological fertilizer for biodiversity, water conservation and sustainable land management

by Rosie Laakeaoekena Keale, ecological and agricultural land management intern at the ranch

At Pine Meadow Ranch, we are committed to finding and practicing sustainable land management while promoting the success of native ecosystems in our region. To facilitate a regenerative and self-regulating agriculture system, we’re exploring opportunities to experiment with different organic mediums that enhance biodiversity, plant growth, soil structure, seed germination and more.

This summer, I am experimenting with compost tea. This is a biological fertilizer that serves as an organic and resource efficient medium to build biodiversity and alleviate the need for excessive watering. By taking advantage of the mature compost from the ranch, we can extend its resource potential by concentrating soluble beneficial nutrients and making them readily available for plants.

Additionally, using compost from the ranch provides beneficial indigenous microorganisms that are adapted to our environment. These organisms will in turn enhance the productivity and success of coinciding native plants, cultivating ecosystem resilience and relieving the need for intensive care. As we prohibit the use of pesticides and inorganic fertilizers on the grounds, aerated compost tea is an amazing alternative for promoting plant and root system health while mitigating harmful insects and disease too.

So, what is compost tea and how do you make it?

Aerobic compost tea is made by suspending a mesh bag of mature compost in an aerated bucket of water for 24 to 48 hours (see details for aeration system below). Soluble nutrients in the compost seep into the water which is then drained and transferred to watering cans to be applied to root systems and plant foliage. Aeration provides oxygen to beneficial microorganisms and helps maintain their growth in the tea. Besides oxygen, adding molasses as a food source for bacteria and fungi, fish emulsion, kelp fertilizer, worm castings, and other catalysts create a nutrient dense environment for mycorrhizal (symbiosis between fungi and plant roots) activity. Yum!

To build the aeration system, I followed the OSU Extension Service plan for a 25-gallon compost tea brewer. After gathering all my parts, cutting them, and drilling 1/16-inch air holes, 1/2-inch apart, the actual setup only took a few minutes.

Check out the video at the bottom of the page of me putting it all together and testing it out for the first time (I was a little excited).

In the video, you can see that I’m not gluing any of these pieces together. By using just slip PVC pieces, you can take the brewer system apart and clean it. If the system isn’t well cleaned, a biological film of anaerobic microorganisms can build up and release strong harmful acids that are bad for plants. Yikes!

This batch of compost tea will brew mature compost, worm castings, molasses, and kelp fertilizer for about 36 hours. Within 1-2 days, the active tea will be applied to our gardens and to a cheatgrass mitigation test site. At this site, we are working to establish native plants in order to outcompete noxious weeds. The hope here is to promote the health and structure of the soil to induce native seed germination and maintain active root systems once they start growing. This compost tea will help increase soil biodiversity, build soil structure and water retention. The tea will house billions of beneficial bacteria, mycorrhizal fungi and positive nematodes occupying the soil web and foliage, so that infectious pathogens and pests will be far less likely to occur.

This brewer can make 25 gallons of compost tea every few days so it would be exciting to see if we can start spraying our pasture area and bring previously compacted and overgrazed soil back to life. As we move forward and keep moving towards operating a closed loop resource system on the ranch, it would be amazing in the future to make our own organic fertilizers and continue to decrease dependence on externalities.

Rosie Laakeaoekena Keale (photo below) graduated with a bachelor’s in environmental science from the University of Oregon earlier this year.

Published On: August 31st, 2022 / Categories: Pine Meadow Ranch, Pine Meadow Ranch Programs /