Efficiency of garden waste compost teas on tomato growth and its suppressiveness against soilborne pathogens
University of Salamanca/Faculty of Agricultural and Environmental Sciences
Compost Tea shows its many strengths once again. Researchers in the agriculturally rich country of Spain performed greenhouse trials on tomatoes with both compost and worm casting teas. The two types of teas were tested for the amount of nutrition present, their affect on fungal pathogens, and their effect on growth. The compost and worm castings were made from the same sources of green waste in order to compare equitably. Tomato were infected with Fusarium, and Rhizoctonia, two well know disease causing fungal pathogens, and the were then watered with one of four dilutions of compost tea. The plants were allowed to grow over a three month season, and then were evaluated for growth characteristics and disease severity.
The ardent scientists found that the both types of teas produced excellent results. The evaluation of the teas showed that there were significant amounts of soluble plant fertilizers present, along with several beneficial plant hormones like the ever-important Indole Acetic and Salicylic acids. The severity of the diseases were drastically reduced through the use of compost teas. The vermicompost tea provided better defense against Rhizoctonia, while the compost tea fought off Fusarium most effectively. The tomatoes that received teas also grew much more. This is easily explained by increased amounts of fertilizing and growth promoting substances in the tea, as well the disease suppressing effects.
Effect of Dry Yeast and Compost Tea on Growth and Oil Content of Borago Officinalis Plant
Journal of Agriculture and Biological Sciences, 2010
Borage is a common flower whose oils contain several beneficial substances that are used in natural and modern medicine. A group of scientists in Egypt wanted to see if they could increase Borage's growth and oil content with the aid of dry yeast and compost tea.
The experiment was carried out over two years in Giza, Egypt. There were 5 groups of plants tested: (1) plants watered with compost tea, (2) plants foliar sprayed with compost tea, (3) plants foliar sprayed with a liquid solution made from dry yeast and water, (4) plants foliar sprayed with tea and also foliar sprayed with yeast, (5) plants foliar sprayed with yeast and watered with comost tea. The plants were compared to a control group that did not receive tea or yeast, though was fertilized and watered similarly.
The Egyptian scientists found that compost tea applications "significantly increased plant height (cm), fresh and dry weight of aerial parts and flowers (g/plant)". Foliar spraying yeast increased "values of fresh weight of aerial parts, number of suckers, seed weight and oil%". In both years, the scientists found that the combination of both watering in compost tea and foliar spraying yeast was the most beneficial.
Not only did the plants grow more productively, but the levels of beneficial substances like alpha-linolenic acid and campesterol significantly increased as well. This is the kind of information you take back to the herb garden and share with all your friends.
Phosphorus availability from rock phosphate: Combined effect of green waste composting and sulfur addition
Journal of Environmental Management
Phosphorus is extremely important for plant growth, yet it's use in agriculture is extremely inefficient. A conservative estimate is that 50% of applied phosphorus becomes unavailable as it binds with other elements in the soil. To help alleviate this, we can thank microbes.
To address this problem, a team of scientists from Italy and Spain added rock phosphate to greenwaste-compost piles at several levels, let the compost go through its thermophilic cycle, and then determined soluble phosphate levels.
The scientists found that soluble phosphorus levels increased with the addition of compost. The increase was most drastic in the treatments that had the lowest amount of rock phosphate added. Furthermore, the addition of rock phosphate made for more efficient use of nitrogen in the compost, retaining it so that it was not lost to the environment. Adding elemental sulfur was also shown to help increase phosphorus solubility. Take home message: add a little soft rock phosphate to your compost pile to create a phosphorus rich biofertilizer.
Effects of selected root exudate components on soil bacterial communities
Root exudates are substances that plant roots secrete into the rhizosphere, stimulating microbial activity which in turn helps to support a healthy soil system and productive garden. The exudates are composed of a mixture of compounds each with its own unique properties.
A group of scientists from New Zealand wanted to know which of the exudate-constituents affected microbial growth the most. They did this by selecting six of the most common root exudate components: sugars (a mixture of fructose, glucose, sucrose), lactic acid, maleic acid, and quinic acid. With these ingredients, five artificial exudates were concocted to make treatments: sugars, sugars+all acids, sugars+individual acids). The artificial exudates were then watered into soil over a 14 day period. After the 14 days, microbial activity was measured (microbial activity can be measured in bulk, it gives us a good idea of population size). Also, the numbers of species (or diversity) in each treatment was quantified.
The scientists found that the most effective recipe to promote microbial activity was the combination of sugars and lactic acid. The high level of microbial activity indicates that this treatment had the highest microbial populations. Interestingly, the sugar/lactic acid brew had the lowest diversity. The most diversity was seen in the sugar/maleic acid brew. Even more interestingly...the sugar/maleic acid had the lowest amount of microbial activity. The scientists suppose that the sugar/lactic acid brew enabled the most efficient group of microbes to quickly proliferate, while the sugar/maleic acid caused slower growth which allowed a diversity of bacteria to grow. The combination of sugars and quinic acid, as well as the combination of sugars and all of the acids produced relatively high microbial activity as well as species diversity. Take home message, use a diverse food source for your teas, and you will have a diverse and abundant microbial community. Thanks Kiwis!
The Effects of Rate and Method of Aerated Compost Tea Application on Yield and Yield component of Tomato (Lycopersicon esculentum Mill.) at Burusa, South Western Ethiopia.
International Journal of Multidisciplinary and Current Research
A group of scientists in Ethiopia wanted to see whether or not compost tea would help improve tomato production. Local farmers are trying to avoid using chemical fertilizers due to economic and environmental costs. Compost tea is a low cost alternative worth investigating.
The scientists and farmers worked together, potting up Roma tomatoes into several groups that each received a different amount of compost tea. The first group received none, and the other four were watered or foliar sprayed weekly with 300, 600, 900, and 1200mililiters of tea. The plants received standard care otherwise.
Several parameters were studied during the experiment, including: plant height, number of primary branches, root length, days to flower initiation, days to first harvest, number of fruit per plant, fruit weight, fruit size, and fruit quality.
It was shown that across the board, compost tea was significantly beneficial. Compost tea helped to grow bigger plants that produced more, larger, higher quality fruit, that were able to be harvested sooner. The total marketable yield of tomatoes was 0.6kg per plant for the control group, and 2.4kg/plant in the high application rate group. That is a four-fold increase in tomatoes to market. That kind of increase in production could lead to improving the lives of thousands of people. Thanks compost tea! (the Materials and Methods section in this paper is worth the read, click the Link Here to learn more)
Properties of vermicompost aqueous extracts
prepared under different conditions
Journal of Environmental Technology
Have you ever wondered why aerating your tea makes all the difference? Well a group of scientists from the Czech University of Life Sciences did. They too their wonder and turned it into a science experiment.
The curious life scientists wanted to see the difference in plant available nutrients in aerated vs. non-aerated teas. To do this, they tested two different vermicomposts, one made with grape pomice, the other horse manure. The composts were placed in buckets and were either aerated or just stirred. The scientists then sampled the brew every 6 hours and tested the tea for: pH, EC, N, P, K Ca, Mg, and a couple of other parameters. They then used statistics to compare the numbers. Their findings were remarkable.
All macronutrient levels increased in the aerated teas. Available nitrates levels more than quadrupled. Phosphorus and Calcium increased by one third. Potassium and Magnesium doubled. Interestingly, the majority of the nutrients were made available in the first 6 hours, having reached their maximum at 48 hours.
The reasons for these nutrients becoming available is attributed to oxidation reactions occurring in the aerated water, as well as microbial forces acting on the compost material. This study helps us to identify yet another source of compost tea's goodness. Thanks science!!!
Metabolomics for organic food authentication: Results from a long-term field study in carrots
A groundbreaking study done by a group of international scientists working out of Belgium has shown that organic produce is identifiable through DNA testing. An area of study called Metabolomics has made this possible.
Metabolomics studies the chemical fingerprints left by specific cellular processes. By looking at what chemicals are left in a cell, scientists are able to determine what has occurred in that cell. Because plants utilize different metabolic pathways depending on their growth conditions, scientists can look for specific metabolites that indicate organic or synthetic fertilizer sources. The actual process involves identifying and quantifying specific mRNA and proteins, then running that information through statistical analysis to determine if the fertilizer source.
In this study on carrots, if researchers knew the harvest year, they were able to identify with 100% accuracy whether or not the root vegetables were of organic origin. If they did not know the harvest year, the success rate was 70-100%.
This study will help to ensure there is no counterfeit produce in the organic section at the market. More importantly, it shows that organic produce is technically different than synthetically grown produce. The residual metabolites found in organic produce could be valuable compounds leading to greater health in those that consume them. This study has many implications, we look forward to learning about all of them.
The Effects of Soil Solarization and Compost on Soil Suppressiveness against Fusarium Oxysporum f. sp. Melonis
Compost Science and Utilization
Soil Solarization is a common low-cost process used to kill soil borne pests and pathogens. Soil is cultivated, moistened, and covered with clear plastic during hot summer months. The plastic covering collects heat from the sun, which is dissipated throughout the moist soil. The soil can heat to above 140F, killing disease causing organisms. Beneficial organisms have adapted to be able to withstand this heat. There are some issues, like whether or not the soil is able to get hot enough to actually do the job. In northern latitudes and coastal climates, the daytime temperatures may not suffice, which can actually exacerbate the problem. The A group of scientists in Jerusalem wanted to know if compost could help the process.
In a simple experiment, melon seedlings were inoculated with fusarium spores and then planted in several soil conditions: non-solarized soil, solarized soil without compost, and solarized soil with compost. Interestingly, the researchers found the compost with non-solarized soil, provided the best resistance to fusarium. Compost with solarized soil was also beneficial.
Since the melon seedlings were certainly exposed to the pathogen, the scientists concluded that solarization actually may be decreasing the microbial biomass enough so much that fusarium was able to become the dominant organism. With the addition of compost, the load of beneficial organisms was able to keep the fusarium in check, thereby reducing the disease occurrence. The take home lesson from this experiment is: if you solarize your soil, add compost in order to maintain a healthy population of beneficial microorganisms.
Biochar accelerates PAHs biodegradation in petroleum-polluted soil by biostimulation strategy
Journal of Hazardous Materials
Pollution is a pretty big problem worldwide, especially in China. Years of lax regulation has created land, water, and air that are far from optimal when it comes to plant and human health. Remediation of theses polluted natural resources is of a growing concern for both public health and future economics.
A group of scientists from the Shijiazhuang University in Hebei, China wanted to see what effect biochar has on helping petroleum polluted soils. Specifically, they looked at biochar made with either sawdust or wheat straw, cooked at either 300C or 500C, and their effect on reducing Polycyclic Aromatic Hdyrocarbons (aka PHAs).
The biologically-minded scientists found that the addition of biochar helped to reduce soil PAH content, though only significantly so with the biochar produced under the hotter, 500C preparation. There was no difference in results between sawdust of wheat straw. Laboratory analysis showed that the addition of biochar actually promoted the growth of PAH degrading bacteria. The experiment showed that the high-heat biochar established favorable soil conditions for microorganisms able to degrade the toxic PAHs. Studies like this show that biochar is likely to play a major role in soil remediation worldwide.
EFFECT OF COMPOST TEA, STREPTOMYCIN AND CUPRAVIT IN CONTROLLING BACTERIAL LEAF BLIGHT OF RICE
Bangladesh Journal of Agricultural Research
Rice is the biggest food crop in Bangledesh, a small country bordering northeast India. A common disease of rice is Bacterial Leaf Blight, caused by the bacteria Xanthomonas oryzae pv. oryzae. One of the common treatments for the disease is Cupravit, a synthetic fungicide that is toxic to people, and other mammals like mice and other rodents. Considering mice are food sources for predatory birds and reptiles, applying a synthetic fungicide is detrimental to organisms higher on the food chain. A group of scientists from the Bangladesh Agriculture University want to help, and they want to do it using compost tea.
An experiment was set up that compared the effectiveness of Compost Tea, Cupravit, and the common antibiotic Streptomycin. Diseased rice plots were given one of the three treatments, and one plot was left as a control group to be compared against. After 14 days of growth, the presence and severity was of the Bacterial Leaf Blight was assessed. The researchers found that the compost tea was nearly effective as the Cupravit as compared to the control, enough so that the researchers concluded that "The compost tea was highly effective to control bacterial leaf blight (BLB) in rice which could replace the chemical fungicides without any risk to human, animal and environment." By switching from synthetic pesticides to natural and safe ones, we can change our landscape back to one of vigor for lifeforms big and small.
In Vitro Evaluation of Compost Extracts Efficiency as Biocontol Agent of Date Palm Fusarium Wilt
African Journal of Microbiology Research
In Morocco, Fusarium Wilt is called Bayoud, and a group of researchers want to keep it from wreaking havoc on its date palms industry. To do this, they investigated what affect compost tea extract had on lab grown Fusarium oxysporum albendinis.
Researchers used tea extracts from chicken manure compost, and olive mill waste. The finished composts were liquefied, some of which was sterilized and some was not. Then, the researchers applied 5 different concentrations (10-40%) of teas to petri dishes, and then set an actively growing Fusarium colony on the dish. The petri dishes were incubated for eight days. The growth of the Fusarium's mycelium was measured from the center of the colony on outward (the longer the mycelium, the less effective the compost extract). The researchers found that the sterilized tea only worked at the highest concentration, but the non-sterilized tea was EFFECTIVE AT ALL CONCENTRATIONS. Fusarium growth was inhibited from 20%-97% as compared to the control group that had no compost extract applied. The higher concentration of tea, the less the Fusarium was able to grow. Considering the low cost of compost tea, this research is great information for any small farmer looking to become more efficient, while also being eco-friendly. Thanks Morocco!!!
Effects of molasses and compost tea as foliar spray on water spinach (Ipomoea aquatica) in aquaponics system
International Journal of Fisheries and Aquatic Studies 2017
Full Article Here
A group of brainy botanists from Bangladesh wondered if they could improve the yield of their water spinach crop by supplementing plants with foliar sprays. The crop is grown in a recirculating hydroponic system using a NFT design (Nutrient Film Technique) which flows shallow water over the plant's root. The effluent of is then returned to a reservoir which contains fish, in this case tilapia. The fish's waste becomes plant food through a microbial process called nitrification. There are limitations to growing certain plants aquaponically, as the nutrient levels must remain low enough to ensure the health of the fish. The use of supplemental foliar sprays is used to introduce essential nutrients that might be in limited supply.
The scientists in this case wanted to see if there was benefit to using a simple aerated compost tea. In the experiment, they sprayed spinach with either aerated compost tea, a molasses solution, or just plain water. They found that the spinach grown with the compost tea spray was significantly heavier than spinach grown with the molasses spray, and well more so than the spinach sprayed only with water. The experiment showed that compost tea has a place in emerging aquaponic technology.
Effects of Soil Quality Enhancement on Pollinator-Plant Interactions
Psyche Journal of Entomology
A group of noteworthy scientists in North Carolina has shown that vermicompost helps pollinators do their thing. A trial was set up with Boston Pickler cucumbers (Cucumis sativus) grown in a commercially available potting soil, one set of plants was amended with vermicompost (at 1/3 volume) and one without (fed synthetic nutrients). The radical researchers then watched how bumblebees (Bombus impatiens) responded to the two different sets of plants.
It turns out, plants amended with vermicompost: 1. Increased visit length of the bumblebees (tastier nectar?) 2. Reduced time to first discovery (more fragrant flowers?) 3. Bumblebees that fed on vermicompost amended flowers had larger ovaries (indicates higher nutrition quality in pollen) 4. Pollen from the vermicompost grown flowers had higher protein content. 5. Sugar content in the nectar of vermicompost fed flowers was slightly higher.
These results indicate that not only does using vermicompost produce higher quality plants, but also helps to increase the health and activity of our precious pollinators. You can do your part by using vermicompost/worm castings in your garden through amending soil or by using it as part of your compost tea recipe. If the worms only knew how important they are.
Evaluation of different types of compost tea to control rose powdery mildew (Sphaerotheca pannosa var. rosae)
International Journal of Pest Management
Fresh compost tea data out of Iran! A group of sagacious scientists evaluated several different types of compost tea and its effects on rose powdery mildew. They made 4 different types of tea: 1. Aerated Compost Tea 2. Non-Aerated Compost Tea 3. Aerated Worm Casting Tea 4. Non-Aerated Worm Casting Tea. They made these teas at two different strengths, a 1:8 and a 1:16 ratio of compost/castings to water. The teas were either bubbled or non-bubbled for 10 days, and then used as a foliar spray on greenhouse grown roses that were susceptible to powdery mildew. Sprays were either made once per week, or every three days. The scientists found that the 1:8 strength Aerated Compost Tea sprayed twice weekly, was the effective in controlling the powdery mildew. More proof that compost tea is well worth the effort if you are working to prevent and eradicate the deleterious effects of powdery mildew. Thanks scientists from the other side of the globe!!!
Researchers in Thailand are in trenches learning about new ways soil bacteria fight off plant pathogens. A Streptomyces was shown to produce a compound that makes plant pathogenic bacteria unable to communicate. Bacterial communication is known as Quorum Sensing, and is shut down by Quorum Quenching Enzymes produced by Streptomyces. Normally, these pathogenic bacteria need to communicate in order to coordinate a successful attack against the host organism. Streptomyces squashes their communication by destroying the chemical signals being sent among the pathogens. It's kinda like blowing up the enemies communication towers. Scientists were able to extract the QQE and successfully use it against the potato soft rot fungus. Click the image to read the full article.
Putting a Stop to Pythium: Humic Acid and Kelp Additives Boost ACT's Effectiveness against Damping Off
Compost Tea as a Container Medium Drench for Suppressing Seedling Damping-Off Caused by Pythium ultimum
The great state of Oregon has graced us with some insight into combatting damping-off caused by the fungal pathogen, Pythium. Researchers at Oregon State University wanted to know how to make the most effective (pythium suppressing) compost tea, so they tested several variables: aerated vs. non-aerated, compost type, tea additives, and dilution rates. The compost types were composted yard waste, vermicompost, and a commercial compost made from manure/agricultural waste. The additives were soluble kelp, humic acid, rock dusts, and molasses.
The researchers grew cucumber seedlings planted in an inert growing medium that had been inoculated with Pythium. The seedlings were allowed to grow for nine days, at the end of which the number of healthy seedlings were counted and compared to the control group (seeds planted in non-Pythium inoculated soil). The various tea treatments were used to drench the soil medium upon the time of planting.
Consistent disease reduction was only observed with the Aerated Compost Tea that had humic acid and soluble kelp as additives (the type of compost did not matter). Also notable, compost teas made with molasses had inconsistent suppressive effects, with a potential increase in disease. Dilution rates lowered effectiveness as well. The take home message: when making a compost tea, be sure you have sufficient aeration, cut back on the molasses, and use humic acid and kelp additives if you want to keep your seedlings happy and healthy.
Which companion plants affect the performance of green peach aphid on host plants? Testing of 12 candidate plants under laboratory conditions
Entomologia Experimentalis et Applicata
Want to deter aphids? Plant some rosemary throughout the garden, African and French marigolds work well too. A group of French researchers designed an experiment that tested how effective 12 different companion plants were at deterring aphids from infesting a garden. The researchers set up two rows of pepper plants inside 13 individual growing chambers (there were 12 companion plants treatments and one control treatment with no companion plant), and then placed adult female aphids on each plant. Then, the various companion plants were set in between the two rows of pepper plants and allowed to grow alongside each other. Each day, the scientists would count the number of adult females remaining on the pepper plants, and also the number of neonate nymphs (baby aphids) that were produced by the adult female.
During the 12 day experiment, the scientists found that the aphids were more likely to flee from the pepper plants that were near companion plants. The control pepper plants did not lose any aphids, as the bugs were happy in their companion-plant-free environment. They also found that rosemary, lavender, geranium, African marigold, and French marigold significantly decreased the numbers of aphids being reproduced on the pepper leaves. In the end, rosemary outperformed the other companion plants in both deterring aphids, and lowering their reproduction numbers. The scientists attribute this effect to the VOC, or volatile organic compounds, produced by the plants. The VOCs signal to the aphids that the vegetation in a certain area near companion plants is not suitable for rearing young, so encourages the bugs to search on for more reproduction friendly fields. It looks like a flat of rosemary will be on the planting list for this spring.
Effects of compost tea treatments on productivity of lettuce and kohlrabi systems under organic cropping management
Italian Journal of Agronomy 2014
In the sunny Mediterranean climate of Italy a group of agricultural researchers looked into the effects of compost tea on two different leafy green crops, lettuce and kohlrabi. The experiment used compost tea made from a thermophilic compost combination of artichoke, fennel, escarole residue, and wood chips. The scholarly gardeners foliar sprayed the kholrabi and soil-drenched the lettuce. What they found was, compost tea works. As compared to the untreated control, foliar sprayed lettuce increased total production by 6% (measured in harvested weight), and more importantly, increased the marketable heads of lettuce by 24%. The soil drenched kohlrabi increased its total production by a whopping 26%, and its marketable product by 32%. That's a lot of kohlrabi. Grazie to the scientists for their diligent work.
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.