Tuesday, April 18, 2006

compost tea please

Anyone who has ever gardened will tell you there is a constant need to replenish the nutrients depleted by crops and there is also a need to protect the harvest from bugs bent on eating your yield. What is an appropriate response to these issues in a post peak petroleum world? Compost tea of course.

The green revolution of the 1950’s and 60’s included advancements in the mechanization of farm labor, further developments in irrigation techniques, genetic modification of plants through modern hybridization AND the introduction of chemical fertilizers and pesticides produced from fossil fuels. The combination of these efforts increased agricultural yields and eventually led to the domination of commercial farming in our grocery stores and across the landscape of America. As with most of the technological developments introduced in the middle of last century the green revolution provided an increase in the availability of a product, namely food. It also broke with thousands of years worth of accumulated knowledge, created a dependency on finite resources about to begin a worldwide decline in availability and brought in extraordinary profits for the corporations responsible for this shift. Damn I am getting cynical. It also made possible a global population boom that may have exceeded the carrying capacity of human life on planet Earth but that’s a discussion for another day.

The price of commercial fertilizers has been increasing dramatically. Commercial fertilizers are made from natural gas. Natural gas production went into decline in this country in 1971. It has recently peaked in production in all of North America. This means if we want to continue utilizing commercial fertilizers even at current rates of consumption i.e. no growth, we will have to import these fertilizers or import liquefied natural gas. This extremely flammable substance must be shipped at ultra low temperatures in specialized sea vessels before being converted back into a gas at particular docking facilities throughout the country; most of which are strongly opposed by the surrounding populations. That sounds simple enough.

Commercial pesticides on the other hand are made from petroleum. Again we’ve seen a steady increase in the price of pesticides. This is due in part to the fact that the price of petroleum has continued to increase(remember U.S. oil production peaked in 1971) but also because of growing pesticide resistance and other manmade troubles. It turns out that the use of Genetically Modified crops actually increases the use of pesticides. Sometimes I’m not sure whether Agrobizcorp is coming or going.

There are other ways to make nutrients available to your plants and to protect them from ravenous pests. In addition to using compost as a way to recycle organic material back into the soil you can also infuse it in water to create a wonderful mixture your plants will love.

Compost tea is the process of using compost to brew batches of liquid containing intense concentrations of microbial organisms beneficial to the health of plants and advantageous to the soil in which they grow. By placing mature compost in water and providing oxygen & food you can create a bloom of these advantageous little microbes. Why would you take the time to foster such a process? The benefit abound.

Using compost tea to water plants or as a foliar spray provides an overall increase in plant health and plant growth. This is achieved first by reducing the shock associated with transplanting. Compost tea also promotes improvement in soil structure by increasing the number of favorable microorganisms in the soil community. These same microbes increase the availability of nutrients in the soil providing more food for the plants. They also lead to an increase in the capacity of the plant to absorb the nutrients as well as an improvement in the ability of that same soil to hold moisture. Evidence, albeit anecdotal shows a reduced need for water in excess of 50% when compost tea is applied on a regular basis. In addition to helping ward off pests by strengthen the plants themselves, the microorganisms in compost tea also help fight natural plant enemies by occupying plant surfaces and competing for nutrients often utilized in unhealthy soils by these same pests. All of these benefits mean better yields and reduced costs, not to mention a reduction in your dependency on fossil fuels. And the best part is it’s so easy. There are commercial systems for brewing large quantities. There are also enterprising individuals already brewing to sell.

More power to them. For brewing your own though you’ll only need the following:

Aquarium-sized air pump with tubing and air stone
5 gallon bucket
Unsulfured molasses or honey

Non-city water
Several handfuls of mature compost

Let’s get started.

1. Fill your bucket with a mixture of compost and water. Use a ratio of 6 to 1; that is six parts water to one part compost.

2. Next place the bucket in an outdoor location where you have access to the electricity
necessary to run the air pump. Position the pump so that you can attach the tube and the air stone and dangle them deep into the water.

3. Drop in your sugar source.

4. Let the contraption sit for three days and your compost tea will be ready. Use it immediately as it will go bad quickly.

5. If you’re going to spray it onto the foliage of your plants you
will want to strain it using cheese cloth or women’s stockings so as not to clog up your sprayer.

That's it! Here are some helpful hints to aid in your effort. Compost is obviously the critical ingredient. Do you compost? This would be a good time to start a pile if you don’t. If you don’t have a compost pile search for an old pile of rotting leaves. Purchasing compost is another short term solution.

The water you use should be from a non-city source. The chemicals in municipal water will kill the organisms you are trying to grow. I use water from my rain barrel. Maybe this would be a good excuse for you to install some of them- perhaps a future post. Well water or water from a lake will work just fine. If you don’t have a good source for non-municipal water fill your bucket with city water and set up the air pump. Run it for a few days before adding the compost. The chemicals should dissipate.

The oxygenation of the water provided by the pump creates an environment in which aerobic bacteria can live. You can see the air bubbles rising to the surface in the photo above. Remember that aerobic bacteria are the good guys that smell nice and benefit your soil. Your compost tea should smell earthy if not sweet. If it smells rotten something has gone wrong. The most likely culprit is not enough air or too much time. The anaerobic bacteria that can’t stand oxygen are smelly and can contain pathogens. Don't use smelly compost tea.

Heat seems to help the process. During the cool weather of early in the spring I use dark coloured buckets. If you’re looking to cut costs keep an eye open as you drive. I’ve found more buckets than I can use on the side of the road.

As with any natural process the method needs adjusting based on your location and situation. Experimentation is as always the best instructor. I occasionally use less compost or sometimes put in more sugar, always testing out change. I have made a bad batch or two but if you stick to the basic directions above you should be able to brew your own compost tea relatively quickly and for almost no money. For those of you who are interested in a fossil fuel free way in which to feed and strength your plants homebrewed compost tea is great.

For more information visit:

Soil Food Web
The Great State of Pennsylvania
The Great State of Texas
Growing Solutions Taunton
Lawn Jockey

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