Agriculture Reference
In-Depth Information
aerated compost tea, but it's mostly just shortened to compost tea. I understand the confu-
sion, but in this topic, we're looking at this new version of compost tea.
What's so great about it? The new system can extract and multiply an astonishing num-
ber and diversity of beneficial, active, aerobic microbes. We mostly want the aerobes (aer-
obic organisms), because they're generally the beneficial ones. Really good compost tea
can contain as many as 100 trillion bacteria per 0.03 oz. (1 ml).
One of the reasons we do this is to inoculate our soil with microbes when we don't have
enough good compost available. The other main benefit is that we can actually inoculate
the leaves of our plants, something we can't do with compost. With more experience, we
can also get fancy and brew specific teas for specific circumstances. We may brew a tea to
combat powdery mildew on grapes, or a tea to alter the microbial population in a soil in
order to allow us to establish an orchard.
There has been some good research on compost tea over the past 10-15 years, mostly
on a larger scale. Vineyards have achieved good control of mildews and even been able to
harvest their grapes
several weeks
early, giving them a head start on wine making. Food
growers have controlled diseases and documented many other benefits for plant health.
Golf courses and parks have reduced pesticide, chemical fertilizer, and water use, substan-
tially lowering costs while creating healthier turf. When I started using it in my gardening
business in 2006, I didn't personally know any other gardeners or landscapers using it. It's
catching on now, but there are still very few professionals taking advantage of these great
benefits of compost tea.
Even Harvard University is using compost tea. They did a one acre test of mostly turf in
2008 using compost, compost tea, mycorrhizal fungi, humic acids, liquid kelp, and an or-
ganic fertilizer. Compared to the control, root growth was two times greater and nitrogen
produced was three to four times greater. Yet they were able to mow 50% less, presum-
ably because there wasn't such a big hit of nitrogen and other chemical fertilizers all at
once which often produces green grass and fast growth, but eventually causes problems.
They cut water use by 30% and that was expected to increase to 50% for a savings of two
million gallons a year. Apparently, all 16 acres at Harvard are now organic.
I've had great success with compost tea in my own gardens and the gardens of clients.
I've controlled diseases such as mildew and insects such as spider mites. It can't be mar-
keted as a pesticide and people have found themselves in legal trouble for doing so, but of
course it can help to control some plant predators because that's what beneficial microbes
do. In some gardens, one application of compost tea has cleared out plant predators
overnight, and perked the plants up as if it was exactly what they needed. In other gar-
dens, a few applications have been necessary, and in other gardens, not much changed was
noticed. Sometimes, an inadequate soil food web is the problem, and sometimes it's
something else.
