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  • From: Bill Shoemaker <wshoemak AT illinois.edu>
  • To: "Market Farming" <market-farming AT lists.ibiblio.org>
  • Subject: Re: [Market-farming] Easy soil fertility test
  • Date: Mon, 1 Nov 2010 13:55:53 -0500 (CDT)

I do not have a PhD Nan, so you don't have to call me "Dr.". Bill is fine.

I've spent 25 years as a research specialist in vegetables and fruits. Plus
I've been a gardener since a young boy (long ago), growing vegetables and
fruits on the prairie soils of central Illinois like my pioneer ancestors.

Much of what I know I've learned through practical experience facilitated by
agricultural plant science studies at the undergraduate and graduate levels
at the University of Illinois. What I love about science is that it prefers
no one. It simply reveals, leaving people to decide what it means. Each must
decide for themselves and live with the results.

I don't believe many of the "weeds" we have trouble with are primitive. Many
are highly evolved plants whose mechanisms for survival are incredibly
resilient. Most are weeds because we create an opportunity for them. When we
till the soil, we largely eradicate plants, creating a wide opportunity for a
void to be filled in the fertile soil. We usually intend to occupy that site
with our crops, but nature says anyone can compete. Like Elaine said, many
annual weeds create 100's of thousands of seeds per plant. They can quickly
germinate, emerge and blanket the soil, daring anyone to compete. A soil
which has had a cover for many years will not have as many seeds. But when
that cover is removed, unless the weeds are prevented a foothold, they will
quickly dominate that site.

Having operated in Illinois most of my life, I've not really seen many soils
that weren't fertile. An exception is pure sand which occupies about 100K
acres in Mason County, where I spent a couple years. Cactus grow wild there.
But so do weeds. The main limiting factor is moisture. Once the soils are
wet, weeds begin to grow. The next limiting factor is nitrogen. If that is
provided, and moisture is available, almost anything will grow in it. We had
a research site that had several treatments there. A couple used chemical
fertilizers. One had no fertilizer. One had the waste by-product from the
Chicago Metropolitan Sanitary District. The last had organic manure as
fertilizer. After a number of years, the two with waste products (human,
animal) had incredibly rich, loamy soil. Vegetables, and weeds, loved it. The
others needed continual applications of fertilizer. All needed water but the
ones with waste treatments held moisture much longer. Fertility was good for
crops, and !
we!
eds.

I grew gardens organically for many years. I needed to use mulch to control
weeds. Even though I did a good job of preventing weeds from producing new
seeds, I still needed mulch to control them. I liked the Ruth Stout method;
deep wheat straw. I've known farmers who were meticulus about weed control
who eventually reduced the weed "seed bank" in their soils enough to reduce
the risk of weed pressure. But they were adament about preventing weeds from
producting seeds. That was in the day when herbicides were new and not used
much by vegetable growers.

I guess I don't believe good, fertile soils "thwart" weeds. Good,
hardworking, smart growers do. I'm sure they don't thwart diseases. Most
diseases are not soil-borne, though I think we have a lot to learn yet about
what we can do with soil to minimize soil-borne pathogen populations. I hope
Elaine makes great inroads there. Obviously we've known about rotation as a
fundamental tool for disease management for a long time. But good, fertile
soils make weeds just as happy as vegetables, perhaps moreso. I'm interested
in learning though, so if well thought-out and executed research shows
evidence of soil management techniques that reduce weed populations and
pathogen populations, I'd like to see it.

Bill



>Yes, Dr. Shoemaker, many weeds evolved to fit a niche: disturbed or
>depleted soil said Dr. Elaine Ingham. Good soil thwarts weeds and
>plant diseases, she said.
>
>In her class last month I scribbled notes like mad for the 2 days
>because this was so new to me. So it's good to try to explain it to you.
>
>Weeds are typically more primitive plants than crops, says Elaine.
>Bermuda grass, she said is primitive grass that thrives when soil
>life is primitive, that is, three times more bacteria than fungal
>biomass. Weeds evolved to grow quick and produce tons of seeds then
>die. Weeds invest only 20% of their energy in roots while veggies
>invest 75%, fruit trees 80%.
>
>Plants and soil biology co-evolved. Higher plants need higher soil
>life, that is more fungus than bacteria. Higher plants feed soil
>life with sugars from the roots. Half their energy goes into "root
>exudates" of sugars, carbohydrates and proteins that nurture
>symbiotic soil life. Ingham said plants putting out these "cakes and
>pies" for symbiotic soil results in them forming a "castle wall"
>around roots.
>
>So you can grow more crops less weeds if your soil life is thriving
>and mature instead of abused.
>
>Weeds also co-evolved to thrive where there is too much fertility she
>said. Thistle, she said, needs 50ppm nitrogen to even
>germinate. Nutsedge 10 ppm. But unlike veggies, they thrive
>if fertility comes in "pulses" for example, people throwing out
>fertilizer now and then. Johnson grass, dandelions too, she
>said. Weeds also like bad compost better than veggies. That is,
>compost that got too hot from too much manure, went anaerobic, and
>looks ashy or grey, she said.
>
>Your feedback appreciated.
>
>Nan
>
>
>At 07:42 AM 11/1/2010, Bill Shoemaker wrote:
>> >
>> >BTW, Dr. Bill, weeds are plants that thrive in half-dead soil with
>> >lots of chemical fertilizers according to Elaine Ingham of
>> >www.soilfoodweb.com She says they don't mind their nutrients
>> >coming in pulses.
>>
>>
>>After fighting weeds for decades, I've come to respect them as
>>competitors who are finely adapted to the situation they find
>>themselves in. If the soil is half-dead, they will still out-compete
>>crops, but they'll have more difficulty doing it. They aren't
>>aliens, or mutants. They're just exceptionally well adapted native plants.
>>
>>By the way, many of the plants we fight as weeds have been used as
>>food by native peoples in the past, such as lambsquarter, pigweed,
>>purslane, etc. They are "undeveloped" as weeds, so they have all
>>their genetic resources for competing in the environments they
>>prefer. Once we start developing them as crops, we strip away
>>genetic traits which work to their advantage as "weeds" to gain
>>productivity, yield and size. Later on, we begin to look to their
>>native ancestors to recover many of those "stripped" traits for
>>resistance, improved nutrition, competitive ability, etc. Examples
>>include western hemisphere crops like tomatoes, peppers, squash,
>>corn, as well as eatsern hemisphere crops, such as apples, or wheat.
>>
>>Bill
>>
>>
>>William H Shoemaker, UI-Crop Sciences
>>Sr Research Specialist, Food Crops
>>St Charles Horticulture Research Center
>>535 Randall Road St Charles, IL 60174
>>630-584-7254; FAX-584-4610
>>_______________________________________________
>>Market-farming mailing list
>>Market-farming AT lists.ibiblio.org
>>http://lists.ibiblio.org/mailman/listinfo/market-farming
>>
>>Market Farming List Archives may be found here:
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>>address and password):
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>
>Nan Hildreth, Houston 713-842-6643
>www.HoustonClimateProtection.org
>
>Make Soil, End Global Warming
>
>"We could end global warming if we restored the fertility in the
>soils in the state of California." Dr. Elaine Ingham, www.soilfoodweb.com
>
>"...global warming can be reversed by restoring biodiversity in the
>soils and in the ocean. ... There is enough land to sequester this
>carbon and it could be done in a decade or two. ... Now that the Oil
>Age is coming to an end, we are entering the Soil Age.
>" http://groups.google.com/group/soil-age
>
>"... a 1.6% increase in organic content of soils humans manage would
>restore atmospheric carbon dioxide levels to normal." says Allan
>Yeomans in
>http://www.youtube.com/user/AllanYeomans1#p/a/u/0/-o2N6vJDLpE Free
>download of his book http://www.yeomansplow.com.au/priority-one-contents.htm
>
>"Soil is the new frontier" Eaarth by Bill McKibben
>
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>
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William H Shoemaker, UI-Crop Sciences
Sr Research Specialist, Food Crops
St Charles Horticulture Research Center
535 Randall Road St Charles, IL 60174
630-584-7254; FAX-584-4610




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