Compost Extract

[Karlotta Neifert]

Compost teas can be made by farmers, landscapers, or home gardeners to enhance crop fertility and to inoculate the phyllosphere and rhizosphere with soluble nutrients, beneficial microbes, and the beneficial metabolites of microbes. Liquid organic amendments available are described below.

Compost extract is a watery extract made from compost suspended in a barrel of water for no more than one hour before use, usually soaking in a burlap sack. The primary benefit of the extract will be a supply of soluble nutrients, which can be used as a liquid fertilizer. However, it will lack sufficient holding time for microoganisms to multiply and grow significantly.

Compost teas are distinguished from compost extracts both in method of production and in the way they are used. Compost teas are actively brewed with microbial food and catalyst sources added to the solution, and a sump pump bubbles and aerates the solution supplying plenty of much-needed oxygen. The aim of the brewing process is to extract beneficial microbes from the compost itself, followed by growing these populations of microbes during the 24- to 36-hour brew period. The compost provides the source of microbes, and the microbial food and catalyst amendments promote the growth and multiplication of microbes in the tea. Examples of microbial food sources are: molasses, kelp powder, and fish powder. Examples of microbial catalysts are: humic acid, yucca extract, and rock dust.

This is the dark-colored solution that leaches out of the bottom of the compost pile and collects on the ground, compost pad, or in collection ditches, puddles, and ponds and is often rich in soluble nutrients. However, in the early stage of composting, it may contain pathogens and would be viewed as a pollution source if allowed to run off site. Compost leachate needs further bioremediation and is not suitable or recommended as a foliar spray.

These include plant-based extracts from plants such as stinging nettle, horse tail, comfrey, and clover. A common method is to stuff a barrel about three-quarters full of fresh green plant material, then top off the barrel with tepid water. The tea is allowed to ferment at ambient temperatures for 3 to 10 days. The finished product is strained, then diluted in proportions of 1:10 or 1:5 and used as a foliar spray or soil drench. Herbal teas provide a supply of soluble nutrients as well as bioactive plant compounds.

Manure-based extracts are a soluble nutrient source made from raw, nondisinfected animal manure soaked in water. For all practical purposes, manure tea is prepared in the same way as the compost extracts described above. However, the manure is placed in a burlap sack and suspended in a barrel of water for 7 to 14 days. The primary benefit of the manure tea will be a supply of soluble nutrients which can be used as a liquid fertilizer.

Looks like some good results there.

What did you use to activate the extract? Did he also supply that to you?

I'm looking at a unit by MidwestBioSystems. 500-1000gal/hr

Living Soils in DownUnder is using that system. Very interesting. =U4NgUmGWrUw

Brewing compost tea, meanwhile, focuses on breeding the microbial colonies in your compost for a biologically rich finished product. A small amount of compost is suspended in water, which is constantly aerated through the brewing process. In addition, some type of food for the microbes is added, with different foods encouraging different species to flourish. The food and oxygen create ideal conditions for microbes to multiply far beyond the typical carrying capacity of the liquid. This means that the compost tea should be applied as soon as possible after brewing, as the microbes will begin to die off as oxygen levels start to drop.

It is also beneficial to brew your compost tea at the same temperature as the environment in which it will be applied to ensure a population of microbes that thrive at those temperatures. Brewing compost tea in a cool basement and then applying it outside in 90 weather is simply a waste of all those organisms that needed the colder temperatures to thrive, as well as the resources you put into aiding their growth.

The process of making compost tea is a kind of fermentation, and the finished product has been shown to be effective in stimulating plant growth as well as treating disease. As many plant pathogens are fungal or bacterial in nature, the application of beneficial fungi and bacteria can provide an effective control. While rigorous scientific inquiry into the efficacy of compost tea is still relatively scarce, there is a lot of promise in the field, especially regarding the opportunity to develop targeted microbial preparations for specific pathogens. In the meantime, compost tea can be used as a general foliar and soil drench to provide a broad spectrum of benefits for your plants.

For a basic compost tea setup, suspend a permeable bag of finished compost in a five-gallon bucket. Add some food for your microbes and use an aquarium pump and airstones to aerate the water for 24-48 hours.

A basic set-up for brewing compost tea can be made easily at home with a couple stops at the hardware and pet store. A five gallon bucket, an aquarium pump and airstones, and a permeable bag of compost will get you started. The airstones will oxygenate the water, allowing microbial populations in the compost to multiply. The addition of some type of food for the microbes is also important to microbial growth, and can even help determine what microorganisms will thrive. Simple sugars like corn syrup encourage bacterial growth, while oatmeal and other grains tend to support more fungal growth. Molasses, however, tends to be one of the most popular foods for compost tea because of its easy availability and its balanced support of both bacteria and fungi.

Iowa no-tiller Ryan Gibbs says a great compost extract starts with high-quality compost. His preferred methods to make it are Johnson-Su bioreactors and vermicomposting. His composts consist of woodchips, straw, alfalfa and livestock manure left to decompose for about 1 year before extraction. Photo: Michaela Paukner

On this episode of Conservation Ag Update, brought to you by Martin-Till, southern Indiana no-tiller Ray McCormick shows off the unique features of his Horsch Maestro 2430 planter. Meanwhile, 40 miles east of McCormick, Strip-Till Innovator Award recipient Chris Perkins shows how chains on his planter deliver ROI in more ways than one.

After the brew bag is filled, we place it in the water and agitate and massage the compost, making sure to break down any large clumps and get as much surface area as possible. We can work the compost by squeezing, pushing it against the sides of the container, swirl it, and shake it to get the most biology out of it.

If you want to increase the number of microorganisms in your extract, you can fill up your brew bag more than once. After agitating the compost in the water, you can replace the compost with a new batch to get double to population of microorganisms.

Compost extract can be used immediately. If, for whatever reason, you immediately need a biological inoculant to put on your plants, and you have no time to brew compost tea, then you can whip up compost extract in a few minutes.

If you missed Part One of this two-part conversation, I strongly recommend you begin there. Understanding the relationships between plants and the legion of microbial life within our soil is key to making sense of this second half of the discussion.

Today, we focus on improving the biology in soil through composting, along with how to brew and use compost tea. As we learned last week, making or purchasing compost locally will pack a greater beneficial punch in your garden than applying a product produced hundreds of miles away.

Quality compost will feed any active microorganisms already residing in your soil, which will encourage them to multiply. Compost also contains a new population of microbes which make their way into the heap from many sources, including the surfaces of the input materials (food scraps, garden debris, etc.).

Consequently, the species of microorganisms present in the compost will depend on the inputs. The balance of life will also be determined by the compost heap conditions. A booming population of beneficial microbes relies on a good balance of water, food (inputs) and air.

The same is true of microorganisms. When they have a good balance of food, they can work harder and faster to break compost inputs down, while also taking quick breaks to, um, reproduce. These creatures recognize when they have an environment primed to sustain more life, and they respond by multiplying.

Just as in soil, life in compost is critically impacted by oxygen. In Part One of this series, Elaine discussed the effects compaction has on life and nutrients in soil. Compaction squeezes out oxygen particles, creating an anaerobic environment which kills life and causes mineral nutrients to convert to toxic substances, including alcohol.

The same responses occur in a compost heap if it becomes compacted. The varying sizes of the materials you add to the heap create tiny air pockets which allow oxygen to move through the pile. As those materials break down, the natural air pockets are lost, so turning the pile periodically with a pitchfork, for example, is an important step to re-infuse the entire pile with a fresh supply of oxygen.

In Part One, we discussed the microorganisms which live on the above-ground surfaces of plants. One of the many jobs of these creatures is to protect the plant against attack from disease. As a spray, compost tea delivers that beneficial soil biology over the entire surface of the plant.

Microorganisms adhere themselves to each other and to the compost material. So, the first step in creating compost tea is to extract those creatures using water. These tiny organisms are mightier than you might think, so removing them takes more than a good soak or running water. It takes a forceful and precise amount of water pressure to disengage them from the compost materials.

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