1. What's under your feet?
Past: What not to do with dirt
3. Present: On thin ground?
4. Future: Dig in
On this no-till cornfield, crop residue is
left on the fields after a harvest to prevent erosion and water
loss. Conventional plows are nowhere to be found. Photo
by Gene Alexander, USDA.
The United Nations Environment Program recently
reported that China's Gobi desert is spreading by more than 10,000
square kilometers per year. The wind erosion and desertification
that contribute to this spread result, in part, from large-scale
industrial agriculture. In this satellite image of eastern Asia,
a large, brownish dust cloud emanating from China is crossing the
Yellow Sea, passing south of the Korean Peninsula on its way to
southern Japan. Photo: NASA.
The world population (now 6.2 billion) has doubled in less than 50
years, with one-quarter million more people added every day. Even
if each family produced only two children, it would take 70 years
for the number to reach a plateau, says Pimentel. Will there be enough
food to feed all those souls? Tackling the population problem is beyond
the scope of this Why File. But we can offer some hints on what land
managers will be up against in the next 50 years.
United Nations has published three population growth estimates.
To keep pace with the medium prediction (nine billion people by
2050), food production will need to increase by 50 percent in
40 years. If the current trend toward meat-based diets continues,
that figure could be much higher.
current farming methods, it takes about half a hectare per person
to provide the rich, high-protein diet enjoyed by Western
Europeans and North Americans. Such a diet could not be supported
for 6.2 billion: There are only .25 hectares of arable land (land
fit for planting crops) per person.
many as 800 million people remain malnourished and up to three
billion have inadequate diets, according to the United Nations
three million kilograms of pesticides are applied each year, but
more than 40 percent of food production is lost each year to pests.
Sounds grim, and it would be -- if farmers
and governments were interested only in preserving the agricultural
status quo. But, says Pimentel, some seeds of change have been planted,
and more are on the way.
The plow did wonders for crop yields, but for
soils it has been more of a blow than blessing. In reaction, conservation
methods like no-till farming are growing in popularity. The World
Resources Institute reports that in Latin America, for example,
no-till farmers operate on 11 million hectares in Brazil, up from
one million in 1991. More than nine million hectares of land in
Argentina is farmed without tillage, an increase from 100,000 in
1990. As a result, costs for weeding, tillage, herbicides and fertilizers
have dropped, boosting profits by up to $200 per hectare (See State
of the World 2002, in bibliography).
"No-till works very well, because leaving
crop residues on the surface of land protects it from wind and rainfall.
It does mean that you have to use herbicides, but if I'm picking
between erosion and herbicides, I'll pick the herbicides every day,"
In ridge tillage (one kind of conservation
tillage), farmers plant seeds in the valleys between carefully molded
ridges of soil. The method prevents some erosion but usually requires
the addition of more fertilizer. Diagram:
"Some 64 percent of agricultural land in the
world is devoted to annual crops," says Wes Jackson, in sharp contrast
to "the way the planet was 10,000 years ago, covered with perennials
and mixtures. Why is it that nature's ecosystems, over millions
of years, have arrived at perennials and mixtures, but people haven't?"
Jackson is trying to change the traditional
picture - fields planted with a single crop, which must be harvested
and the ground plowed every year -- into cropland that mirrors natural
prairies. Using traditional breeding methods, he hopes to convert
annual crops like corn and wheat into perennials. The idea is that
farmers could leave a crop on the ground for four or five years
without plowing, all the while planting mixtures of many crops on
one field to keep erosion at bay.
The breeding process takes years, he warns,
adding that the Land Institute was founded, in part, as a reaction
to the demands of academia. The pressure to publish new results
each year simply doesn't work for agricultural research, Jackson
The single gene approach of modern biotechnology
can't convert annual crops to perennials, he says. "Perennialism
is a way of life, and there are probably hundreds of genes associated
with that way of life, so getting all of the genes responsible
for perennialism and winter hardiness is a huge task,"Jackson says.
" The paradigm we've elected to follow is
not like that of industrial agriculture, nor is it that of the organic
people or the sustainable agriculture people. Sustainable ag people
are forced to deal with annual roots.
"Right now on the organic fields of America,
the soil is bare. They won't plant corn for another two weeks. And
by June 1, those roots will be two or three inches deep. But the
rains are coming and it doesn't matter that they're not using fertilizer
or pesticides. The fact is -- they will have soil erosion. Cover
crop roots are wimpy," Jackson says.
In the end, agriculture will feed the world
only if the world's farmers treat soils with more care than has
been shown in the past, Jackson says. The long-term shift he envisions
-- perennial crops, fields planted with many kinds of seed, and less
reliance on tillage -- may help. But the farmer's ability to make
these changes hinges on social, political and scientific support.
Others say sustainable agriculture won't be
possible at all, on a planet teeming with people. Finding a way
to stabilize the world population at around two billion, Ward Chesworth
says, should take priority.
But there is a consensus on one thing, at
least: As a species, we should watch where we step.
-- Sarah Goforth
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