the fascinating world of bacteria

here's Bonnie Bassler's take on the subject of bacteria:

in the last post, we saw how to make a compost tea (the 24 hour recipe) which is essentially a way of moving bacteria and other microbes from the contents of the compost pile into a liquid that can be applied to our precious plants.

but is that the only method of improving the bacterial content of our soils?  compost teas is but one route to take, as caretaker of the organic realm:

Compost Teas vs. Compost Extracts

First, it may be helpful to share some common terminology and practices associated with compost teas. How do compost teas differ from compost extracts or compost leachates?

Compost Leachate

Compost windrow leachate—the dark-colored solution that leaches out of the bottom of the compost pile—most likely will be rich in soluble nutrients; but, in the early stage of composting it may also contain pathogens. It 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.

Compost Extract

Compost watery extract—made from compost suspended in a barrel of water for 7 to 14 days, usually soaking in a burlap sack—a centuries-old technique. The primary benefit of the extract will be a supply of soluble nutrients, which can be used as a liquid fertilizer.

Compost Tea

Compost tea, in modern terminology, is a compost extract brewed with a microbial food source—molasses, kelp, rock dust, humic-fulvic acids. The compost-tea brewing technique, an aerobic process, extracts and grows populations of beneficial microorganisms.

Summary

Compost teas are distinguished from compost extracts both in method of production and in the way they are used. 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. Some examples of microbial food sources: molasses, kelp powder, and fish powder. Some examples of microbial catalysts: humic acid, yucca extract, and rock dust.

Liquid Organic Extracts vs. Compost Teas

Building on the concept of compost teas as a liquid organic extract, what are some other common organic extracts used as a liquid drench or foliar spray?

Manure Tea

Manure-based extracts—a soluble nutrient source made from raw animal manure soaked in water. For all practical purposes, manure tea is prepared in the same way as the compost extracts described in the preceding section. 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 tea will be a supply of soluble nutrients, which can be used as a liquid fertilizer.

Herbal Tea

Plant-based extracts—stinging nettle, horse tail, comfrey, 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 portions 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.

Liquid Manures

Mixtures of plant and animal byproducts steeped as an extract—stinging nettle, comfrey, seaweed, fish wastes, fish meal. Liquid manures are a blend of marine products (local fish wastes, seaweed extract, kelp meal) and locally harvested herbs, soaked and fermented at ambient temperatures for 3 to 10 days. Liquid manures are prepared similarly to herbal tea—the material is fully immersed in the barrel during the fermenting period, then strained and diluted and used as a foliar spray or soil drench. Liquid manures supply soluble nutrients and bioactive compounds.

Summary

Compost teas and herbal teas are tools that can be made on the farm to enhance crop fertility and to inoculate the phyllosphere and rhizosphere with soluble nutrients, beneficial microbes, and the beneficial metabolites of microbes.

Caution

Wheareas raw animal manures are used as a compost windrow feedstock, the composting process—thermophyllic heating to 135-160° F for 10-15 days—assures pathogen reduction. The raw organic matter initially present in the compost windrow undergoes a complete transformation, with humus as an end product. Any pathogens associated with raw manures will be gone. So caution is extended: Manure teas are NOT the same thing as compost teas or compost extracts. Because of concerns over new pathogenic strains of E. coli, the author advises growers to reconsider manure teas and/or to work with a microbial lab to ensure a safe, worthwhile product.

references above are available from NCAT - National Centre Appropriate Technology

compost tea - the 24hr recipe

there's been a rare old hoo-har about compost tea, here in the uk, since Gardener's World broadcast their April 1st look at the RHS's experiments with this organic method of keeping our plants tip top and healthy.

Of course, the recent e-coli outbreak in mainland Europe shocked many folks into thinking about what goes on to our commercially grow veggies - whether manure-based feeds were robust enough to prevent the transmission of pathogens, or whether they were in part to blame for such a devastating pathogenic outbreak.

The issue of creating safe organic feeds is therefore a crucial one - the oldest form of compost tea comes from the Victorian country garden.

Simply put: a collection of dried "cow-pats" would be placed in a burlap sack, weighted down and placed into a water butt to steep for a few days, before the liquor would be watered into the veggies and flowers for the full fertilizer effect.

It worked well in that time, of course, as they had precious few petrochemicals which might upset the delicate food-chain in the soil food web ( fascinating subject we'll cover in more detail in later blog posts) and no long-lasting man-made compounds which might survive the journey through a cow's intestine and go on to mutate crops, as we had a few years ago with herbicides.

So, what with the concern over e-coli, pathogens from manure, i was reading through a couple of homesteading blogs and came across this recipe from the small measures blog.  It's a guest post by Indio of saving the big money blog in the states and gives a 24 hour recipe for compost tea:

I started out with a control group of plants that didn’t get the compost tea as a point of comparison. Eventually, I took pity on this group and one by one they got hooked on the delicious beverage. There is only one remaining anemic plant from my group of test plants.

This is my first year using compost tea and I quickly became a convert. It’s not a difficult process so I usually have a 5 gallon bucket of tea percolating daily. I alternate between my two vegetable beds and every other day they get a drink when it isn’t raining. With the recent ecoli outbreak in Europe, compost tea is one of the safest ways to add nutrients to soil instead of using animal manure. Rather than worrying about whether or not the manure has aged enough to be safe on root crops, or if it will splash on fruiting crops I’ve found that compost tea is a way to take the worry out of soil enhancement and organic nutritional supplements.

At its most basic, compost tea is made by soaking the compost in non-chlorinated water for twenty four hours to encourage the growth of bacteria, fungi, protozoa and beneficial microbes that will feed the plant either through the leaves or the root system. The tea can be either sprayed on the plants as a foliar spray or used to water the plants. If you soak the compost longer than 24 hours, you risk the microbes dying before they get to the plant so it’s important to use it as soon as it is ready.

The Four Step Process

1. Fill a large bucket with water (water temperature doesn’t matter). If you don’t have well water, then let the water sit for 24 hours prior to adding the compost to let the chlorine evaporate out of the treated water. Depending upon the size of your garden you may want to use something larger than a five gallon bucket, which is what I use for my two modest veg beds.

2. To encourage the microbe development, I add two tbsps of tea catalyst to the water and stir to dissolve it. This is not a mandatory step, but it does accelerate the development of the microbes.

3. An air pump, the kind that is typically used in an aquarium, with two air stones attached to the end of the pump tubing, are used to circulate the bucket water. The air stones are placed on the bottom of the bucket. The whole set up must be located near an electrical outlet because the pump will need to be higher than the bucket so that water doesn’t get sucked back into the pump and break it. The pump speeds up the process by circulating the water and organisms.

4. To make the tea, I use either worm castings or arctic humus. I usually run out of humus quickly, but worm castings I can dig out of the vermicompost bin in my basement. If you don’t have a worm bin, check with your local garden shop for bags of worm castings. Next put the compost in a mesh bag and hang that over the edges of the bucket. Stirring the compost every now and then helps distribute the organisms, rather than letting them get stuck in the compost.

In 24 hours, you can pour the tea into a watering can or use it as a foliar spray. Your plants will show their appreciation by being bountiful.

Now i'm not exactly sure what the tea catalyst might be, but i suspect it may be a commercially available additive from the varying compost tea suppliers in the States.

As we'll find out through the pages of this blog, there are a myriad of ways in which to make compost teas, wines, microbe brews and so on - with varying effects claimed and shown.  The main point that people are finding out, however, is that we don't need chemical or synthetic feeds to care for our plants - in fact these synthetic feeds may have done more harm than good since their introduction (in terms of damaging soil structure and allowing pathogenic species to flourish).

BUGS are part of the coming new understanding about how we can feed ourselves whilst taking care of nature, but remember -
the revolution will not be pasteurized*

* see the about this blog page for more