Dialing In The Compost Tea Recipe: A look at Brew Times, Water Temps, Dilution Rates, and Food Sources
The Improving physico-chemical and microbiological quality of compost tea using different treatments during extraction
African Journal of Microbiology Research 2015
A group of Jordanian scientists wanted to determine what conditions produce more microbes in an aerated compost tea. Four microbial groups were assessed: Total Bacteria, Nitrogen Fixing Bacteria, Actinomycetes, and Fungi. The researchers tested four different brew conditions: Water Temperature, Brew Time, Compost-to-Water ratios, and Food Sources. A basic compost and molasses recipe was used for all the experiments, with additional food sources added for the last experiment.
The water temperatures tested were 68F, 82F, 99F, and 113F. The bacteria grew best at the lower temperatures (68-82F), while fungus and actinomycetes grew better at the the warmer temperatures. Regarding brew time checked at 12, 24, 48, & 72 hours, all microbe populations increased as brew time lengthened. The amount of compost used per gallon of water was found to correlate directly with microbial counts, ie. the more compost, the more microbes. The researcher indicate that a 1:20 ratio (weight to volume) is most efficient, meaning that for every 20 gallons of water only 1 pound of compost is needed.
Lastly, and most interestingly, food sources were looked at. The four microbial food source inputs were: (1)Molasses, (2)Ammonium Nitrate, (3)Potassium Phosphate, and (4) a combination of those three. The results showed that (1)Molasses does contribute to a boost in all groups, though the (4)combination of food sources led to an even greater boost in total numbers and diversity. The treatment with only Potassium Phosphate drastically increased Nitrogen fixing bacteria, while it significantly lowered the total fungi counts. The highest amount of nitrogen fixers were found in the Potassium Phosphate treatment, which showed the lowest populations for the other three groups of microbes.
What do we learn from this? If you want microbial diversity, use diverse food sources, and if you want only nitrogen fixers, feed the tea with potassium and phosphate sources. Lastly, the researchers used inorganic food sources (Ammonium Nitrate, and Potassium Phosphate) in this experiment, we hope that the next time around they look at how organic sources of Nitrogen, Potassium, and Phosphorus affect microbial counts. Thanks to all the researchers out there doing the nitty-gritty work so we can grow happier, healthier gardens.
Antifungal effects of compost tea microorganisms on tomato pathogens
Biological Control 2015
It is becoming well documented that Compost Tea has fungicidal properties, and that those properties come by way of the microbes in the tea. Canadian agricultural scientists wanted to see which microbes were the most effective in control of two different tomato diseases, Botrytis and Alternaria. To do this, the research team identified 4 different bacteria known for having anti-fungal effects in a sheep manure compost tea (Advenella incenata, Aminobacter aminovorans, Bacillus subtilis, and Brevibacterium linens). The scientists were able to isolate the microbes, and then they ran several experiments with them.
In one experiment, the scientists simply grew the microbes on petri-dishes, and then placed actively growing fungal pathogens on the same dishes. They then looked to see how much the fungal hyphae were able to grow. They saw that the bacteria Brevibacterium linens and Bacillus subtilis were able to prevent fungal hyphae from growing at a rate three times that of the control. In another experiment, the scientists took tomatoes, poked holes in them, and inserted either Botrytis or Alternaria spores, and then immediately following washed the wound with a solution containing B. linens and B. subtilis, individually and combined. The results showed that the combination of B. linens and B. subtilis worked significantly better than using the two microbes individually. They also tested spore fungal spore germination, which was also reduced better by the combination of the two beneficial bacteria. This leads one to conclude that biological diversity in a rich compost tea is reason for the improved fungicidal effects.
Maize growth responses to soil microbes and soil properties after fertilization with different green manures
Applied Microbiology and Technology 2016
Are you cover cropping over the winter? According to a group of researchers in China, the type of cover crop is going to influence both your microbial diversity and your yield. Four types of green manure (a cover crop that gets tilled into the soil) were used in the experiment, Common Vetch, Milk Vetch, Vicia Villosa, and Radish. A soil plot with no cover crop was used as the control. The cover crops were seeded in the fall (October), tilled under the following May, corn was seeded right after, and then the corn was grown through the summer and harvested the following September. Upon harvest, the researchers collected soil from each of the treatments, then analyzed it for microbial content. They also collected ears of corn from the treatments and assessed yield characteristics.
The researchers found that Milk Vetch significantly outperformed the control and radish groups in yield, plant height, and cob weight. If fact, corn yield was increased by 31.3% as compared to the control. The Vicia and Common Vetch had slightly higher yields than the Radish and control group. The Radishes did not increase yield (explained by the fact the other treatments were legumes, which fix nitrogen, radish does not). On the microbial end of things, there were variations in types of microbes present in the different treatments. Several groups of bacteria were identified, though the most interesting finding was that the Milk Vetch showed a significantly higher amount of Acidobacteria, while the control had a higher amount of Proteobacteria. Acidobacteria are known to have disease fighting qualities which could have contributed to the increased growth. The Proteobacteria group contains disease causing organisms, as well as microbes that could potentially compete with crops for nitrogen.
The scientists also found that soil pH was lowered by the cover crops as compared to the control group. There was also an increase in the soil's organic matter content in all treatments. The Milk Vetch soil had significantly higher available Nitrogen and Phosphorus than both the control and Radish treatment. These factors would contribute to increased yield. The other treatments did show increases, though the results were varied and not always significant. This study teaches us that specific cover crops have influence on crop yields due to their influence on microbial and physical soil characteristics.
Identification of Diverse Mycoviruses through Metatranscriptomics Characterization of the Viromes of Five Major Fungal Plant Pathogens.
Journal of Virology, 2016
Fungal pathogens reduce total yields by an average of 10% annually, therefore new and effective ways of control are always of interest. A group of researchers from the Univeristy of Illinois evaluated the myco-viruses present in 5 common fungal plant pathogens. Myco-Viruses are simply viruses that infect fungi. The researchers were able to extract DNA and RNA from the fungal pathogens (which would have viral residual DNA/RNA fingerprints) and then compared what they found against a database of known viruses. They found DNA that matched a number of known viruses. Some of the viruses were encapsidated, meaning their DNA/RNA was packaged in a protein shell, allowing them to be transmitted outside the fungus. Because of their inherent hardiness, encapsidated myco-viruses have future potential for use as a fungicide. At this time, the researchers were not interested in their effectiveness in controlling fungal pathogens, rather they just wanted to identify the relations between known viruses and the newly found myco-viruses. Understanding lineage is the first step in developing a myco-virus for use in fighting fungal disease.
INM, it's the new buzz-acronym, and it stands for Integrated Nutrient Management. Similar to Integrated Pest Management, INM is a whole systems approach that looks to maximize soil fertility through the precise and coordinated use of fertilizer inputs. A conventional INM program uses both organic and inorganic fertilizers, along with bio-active inputs such as composts and worm castings and specific microbial inoculates. The goal of INM is to increase soil fertility and keep it sustained and sustainable.
Research is showing us that soils which are fertilized solely with synthetic chemicals become less productive over time. This decline has been attributed to secondary and micro-nutrient deficiencies, as well as a decline in microbial populations. Over-fertilization of soluble synthetic fertilizers can lead to leaching and environmental pollution. Integrated Nutrient Management works to solve these problems by encouraging a healthy and resilient soil microbiota.
As we are seeing in other articles posted to this blog, using Compost Tea is paramount when it comes to keeping plants disease free and abundantly productive. A farm or garden with a good INM program will have a compost tea brewer bubbling somewhere on site. That farm will also have years of healthy growth in its future.
Here are links to a few recent journal articles touting the benefits of a solid INM program:
Vermi-Compost Tea Production and Plant Growth Impacts
Biocycle Compost Research 2007
A team of Ohio State researchers undertook a series of experiments in order to assess a number of characteristics of vermicompost teas and their effects on plant growth. The most significant find was related to aerated versus non-aerated teas. They saw that Nitrate levels were higher in aerated teas. Nitrate is a form of Nitrogen that plants can more readily use. Also, microbial biomass and enzyme activity were greater in the aerated tea, indicating that the number of microbes and their metabolic activity levels were higher. In follow up experiment the brilliant Buckeyed scientists looked at how aeration affected plant growth. They ran trials on cucumber and tomato plants, some with aerated tea, some without non-aerated tea. The differences were drastic (click the Link Here to see pictures) and a significant effect was seen even at the lowest concentration tested, which was 1 gallon of tea in 20 gallons of water. Germination rate, leaf area, and plant height were all substantially increased through the use of aerated tea. It looks like if you're going to brew it, you should absolutely bubble it.
Mass spectrometric evidence for the occurrence of plant growth promoting cytokinins in vermicompost tea
Biology and Fertility of Soils 2014
A group of scientists in Singapore were interested in learning more about the growth promoting effects of vermicompost. In a very simple experiment they produced vermicompost using plant waste and chicken manure with two different types of worms, red wigglers and blue worms. They then collected the run-off (leachate, or tea as the researchers called it) from the vermicompost bin and then analyzed the liquid with a mass spectrometer, which allowed them to look at the chemical constituents of the vermicompost liquid. The spectrometer showed that there were significant levels of 3 different types of growth promoting hormones known as cytokinins. Cytokinins promote cell division, or essentially growth, in roots and shoots. The researchers speculate that the hormones are produced by the microbes in the vermicompost. Thanks again worms! Your unseen labors are thoroughly appreciated.
Using aerated compost tea in comparison with a chemical pesticide for controlling rose powdery mildew
Archives of Phytopathology and Plant Protection 2014
The diligent scientists in Iran found that compost tea outperformed the synthetic pesticide Topaz (a triazole based fungicide) in trials on rose powdery mildew. The experiment was very simple, aerated compost tea was foliar sprayed twice a week, and the synthetic pesticide was sprayed once a week (as per the manufacturers recommendations) on roses in a controlled greenhouse. This was done over a 4 week period, at the end of which, the number of flowers infected with powdery mildew were counted and the numbers were run through statistical analysis. The percentage of control, or how many flowers did not have PM, was calculated and shown to be about 25% higher in the compost tea treatment. Studies like this are verifying that compost tea is an environmentally friendly option when it comes to battling pest and disease.
Comparative evaluation of enzyme activities and phenol content of Irish potato (Solanum tuberosum) grown under EM and IMO manures Bokashi
International Journal of Biological and Chemical Sciences 2014
Scientists from the University of Bamenda in Cameroon were interested in Bokashi's affects on the growth of Irish potatoes (Solanum tuberosum). Their experiment used two different types of bran Bokashi, one inoculated with TerraGanix brand EM (Effective Microorganisms) and one with IMOs (Indigenous Microorganisms). Field beds were prepared, and Bokashis were applied, separately, one week before planting, and again 5 weeks after planting. They found that the EM Bokashi increased stem length and produced heavier potatoes as compared to both the IMO Bokashi and the control group. There were also notable differences in health related phenol content and enzyme activity of the treatment groups, generally being higher in the bokashi treatments. The researchers conclude that the microbes in bokashi sped up the breakdown of the organic matter in the Bokashi and in the surrounding soil, thereby releasing nutrients and supporting increased plant growth. Bokashi is an important part of a healthy and sustainable gardening approach. Thanks Effective Microorganisms!!!!
Effect of compost and earthworm production on soil properties, growth and dry matter yield of maize in crude oil degraded soil
Journal of Soil Science and Environmental Management 2017
A Nigerian researcher has shown that the addition of compost and worms helps to reclaim soil that has been contaminated with crude oil. The study was done with 4 compost types that were mixtures of cassava compost and/or pig or poultry manure composts. The compost was mixed in with soil at a 1:5 ratio (compost:soil), 10 earthworms were added to each soil blend, and lastly corn seeds were planted in each test soil. The control soil was simply oil degraded soil without compost added. The test was ran for eight weeks. At the end of the experiment, all of the earthworms in the oiled soil were dead. The poultry compost had 7 survive, while the pig compost had an increase of worms to the tune of 36 (that's 26 new worms in 8 weeks!). The corn was also greatly affected by the addition of compost. The shoot and root dry matter of the oil-only soil was some 0.46 grams, while the cassava/poultry/pig compost weighed about 90 grams (the other compost/soil mixes had various results worth checking out in the link to the full article). This research shows that there is hope in saving soils that have been damaged by oil spills. A big thanks to the the single scientist, Nweke I. A., that did all this work.
Interactions between biochar and mycorrhizal fungi in a water-stressed agricultural soil
Australian scientists developed a unique way to see how biochar helps in times of drought. A soil chamber that used fine mesh to separate sides was used to see just how far mycorrhizal fungi will go to help out. They saw adding biochar helped the beneficial mycorrhizal fungi to colonize plant roots. Under the water stress conditions, the biochar treated soil grew plants with longer shoots with higher phosphorus content. This matched up with what they saw underneath the microscope. The biochar soil had more fungi-root colonization, with longer fungal hyphae.
Effect of aerated compost tea on grapevine powdery mildew, botrytis bunch rot and microbial abundance on leaves
European Journal of Plant Pathology 2013
Botrytis and Powdery Mildew are two major fungal diseases that affect a very wide range of plants. In this study, researchers way down under in Tasmania were able to suppress the two diseases on grape bunches and grape leaves with compost tea. The compost was made from a mix of manures, forest products, and salmon fishery waste. Leaves and bunches were inoculated with diseases. The control group was not sprayed with teas, while the test groups were sprayed at 3 times before and three times after inoculation (at 4 day intervals). The researchers saw that compost tea reduced the severity of infection (area of leaf surface or grape bunch affected) to less than 1%. Non-treated plants had severity levels of 15-77%. This is huge. Compost tea was able to prevent virtually any incidence of PM or Botrytis. I think I'll be doing a little foliar spraying this afternoon.
Compost Tea Reduces Egg Hatch and Early-Stage Nymphal Development of Halyomorpha halys (Hemiptera: Pentatomidae)
Florida Entomologist 2014
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Scientists in Florida have shown compost tea helps control brown marmorated stink bugs. These stink bugs are a significant agricultural pest in the US and around the world. A non-areated compost tea extract made from a mix of mushroom compost and chicken manure was sprayed on egg masses laid by the stink bugs. The researchers found that the egg masses had a 13% drop in hatching, and even more improtantly, the nymphs that hatched were 3 times less likely to survive their first stage of development. The researchers do not conclude why compost tea has this affect, but do speculate that the microbes in tea may interfere with bacteria that live in the stink bug's gut. I wonder what other bugs are bugged by my tea?
The use of Bacillus mycoides and Bacillus subtlis as biocontrol agents for the fungi causing root rot disease in common bean
Egyptian Journal of Biotechnology 2013
Full Text Here
Researchers in Egypt were able to show that Bacillus mycoides, found in Soil Life, was able to fight off the common fungal diseases Fusarium solani, Rhizoctonia, and Slcoritium rolfsii. The scientists cultured the bacteria from the soil, isolated them, and ran a bunch of tests on them. Not only did they fight off the fungal diseases, they were also shown to produce chitanases, proteases (which would disrupt fungal growth), they also produce two very important plant growth hormones, Indoleacetic acid and Gibberellic acid. Microbes magic!!!
Effects of the main extraction parameters on chemical and microbial characteristics of compost tea
Journal of Waste Management 2016
This study used heavy statistics to show that tea should be brewed for not much longer than 48 hours, and used immediately. The compost was made from manure and greenwaste, and was brewed for up to 6 days, then stored for up to 6 weeks. The numbers show that a short brew time and immediate use will lead to a higher quality tea and response therefrom.
Enhancing sustainability of a processing tomato cultivation system by using bioactive compost teas
Scientia Horticulturae 2016
In a 2 year study, an Italian research team has shown that aerated compost tea helps tomatoes yield more, resist disease, and helps them initiate more root growth. The researchers used 4 different types of compost, of which the manure based compost showed higher amounts of available nutrients, while the green-waste based compost helped initiate more root growth.
Potential Impact of Compost Tea on Soil Microbial Properties and Performance of Radish Plant under Sandy Soil conditions - GreenhouseExperiments
Australian Journal of Basic and Applied Sciences 2016
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Radishes treated with compost tea had 150% Nitrogen , 92% more Phosphorus, and 253% more Potassium content in their leaves than those that were untreated. Compost tea helped the plants uptake nutrients in a major way.
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.
Properties of vermicompost aqueous extracts prepared under different conditions
Journal of Environmental Technology 2016
This paper shows the extraction efficiency (ability to measure) of N, P, K, Ca, & Mg all increased 33-50% in an aerated compost tea, as opposed to a non-aerated tea. The researchers used two different vermicomposts (horse manure being one, and apple pomace the other) under two conditions, aerated and non-aerated. This highest levels of nutrients extracted were seen after 48 hours of brew time. I had learned long ago that the main benefit was the addition of microbes, and not so much the nutrients, looks like there's some more learning to do.....