[permaculture] Fwd: Re: [SANET-MG] fertilizer and damage to soil microorganisms
Lawrence F. London, Jr.
lflj at bellsouth.net
Sun Dec 5 21:57:30 EST 2010
-------- Original Message --------
Subject: Re: [SANET-MG] fertilizer and damage to soil microorganisms
Date: Sun, 5 Dec 2010 19:26:27 -0500
From: Elaine Ingham <soilfoodweb at AOL.COM>
To: SANET-MG at LISTS.IFAS.UFL.EDU
In the past, I looked at how much of some commonly applied inorganic fertilizers could be applied to soil without
harming the majority of organisms.
We did testing, and in healthy grassland or turf soil, we saw little damage to the organisms present in that soil if
less than 100 pounds per ac (or 100 kg per hectare) were applied.
Convert that to a typical lawn of 100 by 100 ft square, and it comes to, oh, about a quarter cup of fertilizer over that
If the soil has suffered damage already, and many of the sensitive organisms are already dead, then that rate could be
perhaps doubled, and we would not detect reduction in biomass. Concentration as well as how healthy the soil is to
begin makes a difference in how much can be applied without a detrimental effect to the organisms.
Of course, you have to use methods that can actually detect organisms in the soil. So, the Solvita Test is not
appropriate, since many inorganic fertilizers have carbonate in them either as a stabilizer, or as part of the
fertilizer mix, and thus CO2 generated is merely a result of the carbonate reacting with hydrogen in the soil. Plate
count tests are completely inappropriate, because they can't detect 99.9999% or more of the species of microorganisms in
soil to begin with. Enzymes can't be used, because of the immobilized enzyme material sequestered on clays or silts or
organic matter masks any change in enzyme activity.
What assays to use then? Direct microscope analysis, where diversity of morphological types (shape, diameter, color,
ornamentation, etc) estimates what organisms are present and is simply, inexpensively and rapidly performed, or DNA
analysis and sequencing, would give solid answers. Nucleic acid methods that only assess a part of the microbial
community, or only assess bacterial diversity, are clearly not adequate either.
In recent years, I've come to question why, in a healthy soil, we would need any inorganic fertilizer at all.
As long as the food web is intact in the soil, microorganisms cycle the enormous quantity of mineral nutrient in sand,
silt, clay and organic matter into plant available, or soluble, forms of all those mineral nutrients.
It is what happens in forests and productive grasslands. Those processes occur at rapid enough rates to maintain plant
production levels far higher than any agricultural field you want to look at. So why can we not use those same
biological processes in agricultural fields, or a lawn, or a garden. No one has ever run out of sand, silt, or clay,
the mineral fraction, in their soil, have they? People may have mistakenly damaged the biology that does the cycling,
however. And that is why chemists can document that nutrient pools are depleted. But that is only because the life in
that soil has been lost. With return of the correct food web, those cycling processes return.
And then, why apply inorganic fertilizers? Even if you lived in a swamp, and had no sand, silt, or clay, there's plenty
of organic matter. Organisms are still required to do cycling of the nutrients from the organic matter, of course.
Nitrogen is possibly an "exception" to the sand, silt and clay mineral nutrient cycling processes performed by
organisms. We need nitrogen-fixing organisms to rapidly fix nitrogen. But this is a biological process. If you add
high amounts of inorganic fertilizers, (more than 100 pounds per acre), then you start to wipe out that
nitrogen-fixation set of organisms, and inorganic fertilizers will be required. Nitrogen-fixing organisms still need a
full food web to cycle the Nitrogen they fix into plant available forms of nutrients. Without the right sets of
organisms, natural nutrient cycling cannot occur fast enough to maintain plant production.
Forests..... please remember to include the herbaceous layer, the grass layer, the shrub, vines and bush layer, the
understory trees, as well as the canopy, when calculating production on an annual basis in a forest. How does a forest
system manage to maintain nutrient supply, without any inorganic nutrient additions. Remember, all the biomass tied up
in tree trunks does not get returned to the forest floor each year. More than what humans remove in harvested food
material is tied up in tree biomass, not returned to further plant growth, on an annual basis. So, how can that forest
keep growing, for several hundred years, with tie-up of all that nutrient on an annual basis? check out the
nitrogen-fixer in a forest...... and the fact that organic matter is accumulating in that forest. Nutrients
not-returned to he next year's plant production. A forest doesn't run out of nutrients, does it..... it doesn't run
out of sand, silt, or clay.......
So, when your transplants start looking puny, consider what that really means. The natural nutrient cycling processes
prevalent in natural soils from which your flowers and vegetables came from, is not functioning in the "potting" soil.
Why aren't the organisms there, doing what they are supposed to do for your plant?
Ah- hem, because they were killed somewhere along the line, and they aren't there anymore. The organisms were killed.
How do you fix that?
Put the organisms your plant needs back into that soil. Make AEROBIC compost. Not smelly, not black, not stinky.
Add the organisms your plant needs to the potting soil, make sure the full food web starts working. Then plant your
plants. Add water the way nature adds water.....without excess inorganic nutrients in it.
What if you can't get the right biology going right at first? Ok, then low levels of organic or inorganic nutrients
while you get the biology established. Like kelp products, or humus, or organic matter of some kind, and then use
compost or compost tea where you have looked to make sure the organisms you need are present before you add them.
A couple weeks later, look again to see if the organisms have improved.
Nature Tech has some simple books just about ready for publication about this -- 10 easy steps.
Come to a class in Corvalllis, either 2 day intro, or the full 5 day course, if you really want to understand how
biology and chemistry work together to grow healthy plants.
Elaine R. Ingham
President, Soil Foodweb Inc.
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