Re: % leaf coverage

From: Elaine Ingham (Soilfoodweb@AOL.COM)
Date: Mon Jan 20 2003 - 09:13:37 EST


We look at the leaf surfaces using a microscope.

How much of the leaf surface is actually covered with organisms? We generally include the area around the bacterium that the bacterium is covering with their glue layer, or slime layer, or glycocalyx - whatever you want to call it.

Some bacteria may cover 4 to 5 micrometers out from their body, sometimes more.

Fungi also have to be counted in determining coverage.

So, not a calculation, we measure.

One point about "wasted tea" that doesn't get to teh plant leaf surface - there's nothing wasted about what doesn't get on the plant leaves. Where's the tea go that doesn't land on the plant aboveground tissue?

To the soil. Think maybe that the organisms can help in the soil?

It has been interesting looking at whether there is any benefit to this "missed the aboveground plant" tea. Several growers we have worked with measured soil biology before they started and a year later after spraying the plants foliarly twice a month all summer.

One grower found no difference in the life in the soil after a year. Another grower saw a 400% increase in bacteria, a doubling of fungal biomass, protozoa increased from less than detectable, to over 30,000 per gram soil, and a reduction in root-feeding nematodes, an increase in beneficial nematodes. VAM colonization went from 2 to 5%, up to 20 to 30%. Not at the foodweb we want to see yet, but well-along the way.

Why the difference in results? It took some investigation, and some poking at the first grower to figure what happened where no improvement was observed. He was pretty unpleasant to deal with in trying to figure it out too.

What do you suppose he was doing? Yep, he applied sulfur, round-up, and lime to the soil during the course of the year. I am fairly sure the sulfur was actually a copper sulfate. All of these things can be very detrimental to active organisms in the soil.

And he couldn't figure out why the biology in the soil didn't improve? Tea is not a chemical, you can't treat it like an inert substance. Life reproduces, increases in number, in the right conditions. Apply things that will kill those organisms, and oh, surprise, you don't see a benefit.


Elaine Ingham
President, Soil Foodweb Inc.
Corvallis, OR
Port Jefferson, NY
Lismore, NSW, Australia
Hilversum, The Netherlands
www.soilfoodweb.com

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