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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Down On The Farm? Yields, Nutrients And Soil Quality
  • Date: Mon, 16 Jul 2007 10:12:31 -0600


right problem, wrong answer

8 June 2007
Down On The Farm? Yields, Nutrients And Soil Quality
By Rusty Rockets
http://www.scienceagogo.com/news/farming.shtml

Today, modern agriculture supplies us with a surfeit of just about any food
we might desire, but at what cost? While systemized, large-scale
agriculture delivered last century's much ballyhooed agricultural
revolution, history tells us that unsound farming methods can cause the
collapse of civilizations. As Jared Diamond has frequently pointed out,
past civilizations have literally farmed themselves to death, by ravaging
surrounding resources, using habitat-incompatible farming methods, and
living at a resource deficit; which all inevitably leads to societal
collapse. Now, it seems, Western civilization may once again be staring
down the barrel, as studies into today's commercial farming practices show
that they are having a negative effect on crop yields, nutrient content and
the environment.

Large-scale farming dates back to around 5,000 BC, when the Sumerians moved
on from subsistence farming to methods that required large tracts of land
and a sizeable labor force. Then, some centuries later, enterprising Romans
honed these Sumerian farming techniques, so that they could cultivate crops
and use them as another source of trade. Down through the centuries,
techniques such as crop rotation, plant selection, crossbreeding,
mechanization and industrialization led to a renaissance in farming, and an
explosion of culinary delights at our fingertips. But while we grumble
about the wonky wheel on our supermarket trolley, or the long cues at the
checkout, some very real agricultural problems are now starting to emerge.

There has been a lot of press about the effects of herbicides and
pesticides on human health, but it is now becoming apparent that
"agrichemicals" - herbicides, synthetic fertilizers and pesticides - are
detrimentally affecting the fundamental growth mechanisms of plants.
Scientists from the University of Oregon have just finished a multi-year
study into the effects that artificial chemicals, such as the insecticide
pentachlorophenol (PCP), have on crops; either through direct application
or run-off. In their paper, soon to be published in the Proceedings of the
National Academy of Sciences (PNAS), the team writes that around 20 of
these chemicals interfere, to varying degrees, with the natural process of
nitrogen-fixing communication between plants and soil bacteria.

Nitrogen fixing is the process by which nitrogen in its molecular form (N2)
is absorbed out of the atmosphere by plants and transformed into nitrogen
compounds, such as ammonia. Nitrogen fixing is important to the success of
market crops, as the ammonia produced acts as a natural fertilizer. But
most market crops are dependent upon rotation legume crops – the
predominant family of nitrogen-fixing plants – such as alfalfa and
soybeans to do the fixing for them. This is because legume plants have the
special ability of secreting a chemical signal that "enlists" friendly
bacteria to convert nitrogen into ammonia. Which is where the problem lies.

The team of scientists, led by Jennifer E. Fox (pictured), a postdoctoral
researcher in the Center for Ecology and Evolutionary Biology at the
University of Oregon, found that artificial chemicals that come into
contact with legumes block the plant's ability to enlist bacteria.
"Agrichemicals are blocking the host plant's phytochemical recruitment
signal," said Fox. "The agrichemicals are cutting the lines of
communication between the host plant and symbiotic bacteria. This is the
mechanism by which these chemicals reduce symbiosis and nitrogen fixation."

The upshot of this is that crops don't get the natural fertilizers that
they require, which results in a "vicious cycle" of increasing use of
agrichemicals in subsequent years to try and boost crop yields, explains
Fox. "We showed that by applying pesticides that interfere with symbiotic
signaling, the overall amount of symbiotic nitrogen fixation is reduced. If
this natural fertilizer source is not replaced by increased application of
synthetic nitrogen fertilizer, then crop yields are reduced and/or more
growing time is needed for these crops to reach the yields obtained by
untreated crops."

This previously unconsidered explanation for progressively poorer crop
yields just adds to a growing list of farming woes, which researchers like
Fox have known about for years. Farming methods such as overuse and tillage
also lead to poor soil quality, explains Fox, because it strips the soil of
nitrogen and phosphorus, interrupts root structures, and upsets
nitrogen-fixing bacteria. In fact, farming methods and poor soil quality
have become so synonymous that a slew of books are being released on the
subject.

In the book Dirt: The Erosion Of Civilizations – perhaps a nod to
Diamond's Collapse: How Societies Choose To Fail Or Succeed – author
David Montgomery, a University of Washington professor of geomorphology,
warns that we humans are stripping the Earth of its fertile soils with our
archaic farming methods. Over thousands of years our ancestors used the
land to farm, and when that land became barren, they moved on to more
fertile lands.

But now that thousands of years have passed, and we continue to rely on
age-old farming techniques, Montgomery warns that the grass is no longer
greener on the other side. "We're doing the same things today that past
societies have done, and at the same rate," says Montgomery, who spends
most of his time studying the evolution and structure of the Earth's
surface. In short, Montgomery believes that we are slowly skinning the
planet of its life-giving soil. "It only takes one good rainstorm when the
soil is bare to lose a century's worth of dirt," laments Montgomery.

Citing tragic periods in America's history, such as the desolate Great
Plains during the Dust Bowl of the 1930s – a hopelessness, and bleakness
articulated in John Steinbeck's novel the Grapes Of Wrath – Montgomery
lays the blame squarely for such miseries upon primary farming methods. He
explains that plowing underneath crop remains, even on flat lands, loosens
and exposes the soil to winds and erosion for extended periods, and
eventually, drives people off of their farming lands.

Such erosion is expected on sloping lands, where rain and wind constantly
reshape hills and mountains that have no vegetation coverage. "If you take
sloping land and strip the plants away, it leaves the soil bare and
exposed. There will be a huge impact the next time it rains or when the
wind blows," says Montgomery. "Plow-based agriculture can change the
erosion rate of even a flat place like Kansas into the erosion rate of a
place like the Himalayas. Basically that type of farming is remaking the
surface of the planet."

Stripping lands of their topsoil in this way is one of the primary reasons
that people move about on this planet, says Montgomery, to find new farming
areas and repeat the process. But with now more than 6 billion hungry
mouths to feed, Montgomery thinks it's finally lunch... er, crunch time.
That is, there are no longer any rich new areas to farm. "We're farming
about as much land as we can on a sustainable basis, but the world's
population is still growing," says Montgomery. "We have to learn to farm
without losing the soil." But how do you turn and prepare the land without
risking the topsoil?

The answer, according to Montgomery, is that you don't. He says that we
should give up tilling agriculture altogether, so that soil erosion
approaches something closer to its natural rate. Instead, tilling and
plowing would be replaced by a method called disking, where crop stubble is
mixed in with the valuable topsoil. The one downside is that more
herbicides may be required to keep an inevitable increase in weeds down,
but he adds that less farm machinery fuel would be needed to tend crops.
"We don't have to farm the way we do. It's as much a matter of culture and
habit as it is of economics, and our habitual ways of farming have gotten
people into a lot of trouble through the years," explains Montgomery. "It's
more of a conceptual shift than anything else, but it's a conceptual shift
that conserves the soil."

Only about 5 percent of the world's farmers – mostly in the US and Latin
America – use no-till methods, says Montgomery, so it could be some time
before we see a shift in farming practices. Let's hope it won't be too
late.

Related articles:
Can Biodiverse Farming Feed The World?
Food, Notorious Food
Wealth Of Nations A Matter Of Climate
Yes, We Have No Bananas
Increasing Soil Erosion Threatens World’s Food Supply
Second Agricultural Revolution In The Offing





  • [Livingontheland] Down On The Farm? Yields, Nutrients And Soil Quality, TradingPostPaul, 07/16/2007

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