Compost Tea

Compost teas proven as effective biocontrol agent to inhibit plant diseases.

Thanks to Compost Tea Lab for sharing some scientific research regarding how and why compost tea works.

Utilization of compost tea for biochemical response assessment
associated with resistance to phytopathogen causing leaf spot
in Melicope ptelefoli

October 2018
Organic Agriculture
Link Here

Malaysia's warm temperatures and wet climate create almost greenhouse like conditions that can be great for growing plants, but also great for culturing plant-disease causing fungi.   Researchers from  Malaysia's University of Technology wanted to  determine what affect compost tea had on the growth of the leaf spot causing Grammothele lineata. The test plant was the Asian herb Melicope ptelefolia which is known for it's edible and medicinal qualities. 

Researchers used two types of teas in the experiment, both were aerated, one of which was supplemented with Molasses.  The researchers then made several concentrations of the tea and dipped leaf leaves into it.  The leaves were then sprayed with a solution that contained the Grammothele spores.  The infected leaves were incubated for a week and then the severity of infection was documented.  The leaves were also tested for the amount of naturally occurring plant defense chemicals present in their tissue.  

What they found was that both teas (with and without molasses) inhibited the growth of the fungal disease by up to 78%.  The highest concentration (40% tea by volume) of molasses brewed tea was the most effective.  The control leaf, which was sprayed with spores only, was completely infected.  Moreover, the leaves that had tea applied to them produced more natural plant defense chemicals (Peroxidase and Polyphenol Oxidase).  The tea boosted the plants own ability to fight off disease.  This is an impressive new discovery in the compost tea realm, as most literature points to compost tea helping reduce infection through competitive exclusion.  This is yet another reason to start using compost tea in your gardens and on your landscape.  Thanks Malaysian scientists for furthering our understanding of why this living fertilizer is such a beneficial substance. 

Product Spotlight - Baseline

If there is one liquid ingredient worth having around, it’s baseline. Baseline is:

A soluble liquid supplement that feeds beneficial microorganisms; an excellent source of humic and fulvic acids.

It can be used in conjunction with an existing organic or synthetic liquid fertilizer program. It:

•Increases nutrient cycling

•Is an excellent ingredient in compost tea

•Can be used as a stand-alone foliar spray or root drench

•Can be used in drip irrigation systems without clogging emitters

While more expensive than other powdered humics, baseline has many benefits. First off, it is of the highest quality humus and will not create nutrient deficiencies, lockouts or other irregularities sometimes observed with powdered humics. Additionally, its liquid nature makes for rapid tank mixing, unlike other humic powders that get caked onto tank sidewalls and congeal into black clay like dots all over your equipment.

Baseline is basically like plasma for your plants and is a key component to the health of mother plants or any plants that spend many months root bound in containers. Root bound plants can be continuously regenerated by weekly applications of baseline and other microbial products.

Here is a short vimeo video demonstrating the use of baseline in a small nursery in Humboldt County:


Compost Tea Feeding Schedules

Compost tea made with all liquid ingredients

Compost tea made with all liquid ingredients

Compost tea can be an effective strategy for balancing feeding schedules. But in the case of compost tea, more is not necessarily better. In fact, over application can actually cause significant soil imbalances. Many times, the problem of over-application of compost tea becomes compounded when the soil remains over-saturated for too long after the application of compost tea, especially if it is being used at every watering. If the microbes have a big boom cycle but then the soil is water logged, the bust cycle will lead to a much quicker anaerobic state, which can lead to a number of different problems.

There are many instances where compost tea is only applied 1x month to outdoor plants with excellent results. Just because you are seeing excellent results with compost tea, doesn’t mean that adding more will work even better.

Feeding Schedules for Rapid Growth

This compost tea was tank mixed with a few biostimulants just prior to watering.

This compost tea was tank mixed with a few biostimulants just prior to watering.

  1. Liquid Fertilizer

  2. Compost Tea

  3. Water

A very successful regime observed in Humboldt County involves transitioning between liquid fertilizers, compost teas and watering.  So one would use their liquid fertilizer on the first watering, the second watering would be the compost tea and the third watering would be plain water. Depending on site specific conditions, you may want to repeat that schedule or mix and match in different patterns. Some growers dilute the tea and some apply it as full strength. Sometimes they mix it with liquid fertilizers. Some growers pre-amend their soils with organic fertilizers and then simply use compost tea periodically (~1x-2x month) throughout the growing cycles.

Whatever methods you decide to choose, know the backbone to any good compost tea is:

  • Compost/Humus

  • Worm Castings

Cherry Zkittlez grown with compost tea

Cherry Zkittlez grown with compost tea

All the additional ingredients you add will depend on your knowledge of the plants life-cycle and current soil biology. There are ways to brew grow teas, bloom teas, high bacterial teas, high protozoa teas and fungal teas. People use molasses, fish hydrolysate, frass, alfalfa, glacial rock, kelp, straw and many other ingredients, but the backbone always starts with a HIGH QUALITY compost or castings.

That’s the quick lowdown on compost tea feeding schedules, if you feel like you have something to add or would like to share your regimen, please utilize the comments below. Happy Brewing!!!

By: Russell Pace – President of the Cannabis Horticultural Association



~Humboldt Earth Technologies~

As growers we always seem to be searching for the next level. Larger yields, higher quality and ways to cut costs are the general directives we aim to achieve. Within this industry however, there seems to be an overuse of synthetic fertilizers with little understanding of the biological systems involved in nutrient uptake and disease control. Many inexperienced growers overuse synthetic fertilizers, hoping that more nutrients means higher yields. All that really happens is a massive salt buildup, which leads to dead microbes, nutrient lockout, a lot of flushing and heavy fungicide spraying.

Effect of Aerated Compost Tea on the Growth in Organic Cultivation

Effect of Aerated Compost Tea on the Growth in Organic Cultivation

Effect of Aerated Compost Tea on the Growth Promotion of Lettuce, Soybean, and Sweet Corn in Organic Cultivation
Journal of Plant Pathology 2015

Here we see that Compost Tea is well worth the effort.   Four types of compost were brewed and then the available nitrogen was determined, as well as the density of microbial communities, along with their affect on plant growth characteristics.  Across the board it was shown that aerating compost tea released more nutrients, increased microbial counts, and helped plants grow.  Way to go AACT.   

Article Courtesy of TeaLab

Compost Tea

Gardeners all know compost is terrific stuff. But there's something even better than plain old compost, and that's compost tea. As the name implies, compost tea is made by steeping compost in water. It's used as either a foliar spray or a soil drench, depending on where your plant has problems.