In
Context #1 (Spring, 1999, p. 9); copyright
1999 by The Nature Institute
Ecological Agriculture Enters the Mainstream
Craig Holdrege
When articles arguing for a fundamental shift toward ecological thinking
and practices in agriculture appear in major scientific journals like Nature
and Proceedings of the National Academy of Sciences, you know a tide
is turning. The long-term consequences of high-input, symptom-neutralizing
or enhancing agricultural practices are so glaring that they can no longer
be ignored by scientists.
Whether it is herbicide or pesticide resistance in weeds and insects
or fertilizer run-off polluting water, again and again "the attempted
solution becomes the problem." W.J. Lewis (1997) and his colleagues—USDA scientists in Georgia—argue that the search for the "silver bullet"
in pest management is futile. Rather, scientists and farmers must begin
to view the farm as a total ecological system. Within this framework the
primary question is no longer how to get rid of the pest as quickly as
possible, but "why is the pest a pest." The pest reflects some imbalance
in the whole and it's a matter of promoting inherent strengths within
the farm ecosystem to create a new balance.
Last fall L.E. Drinkwater (1998) and his colleagues at the Rodale Institute
in Pennsylvania published the results of a 15-year study comparing the
conventional system of maize/soybean rotation using mineral fertilizers
and pesticides with two organic regimens involving crop rotation and either
legume cover crops or cow manure as fertilizer. The average annual yield
was similar in all three systems—one more example debunking the myth
that organic methods are intrinsically not as productive as conventional
ones and therefore inadequate to "feed the world."
But there were also significant qualitative and quantitative differences.
The soil fertilized with manure had an overall build-up in fertility—measured in nitrogen and carbon content—while the conventionally fertilized
soil became less fertile, with about fifty percent more nitrogen leeching
from the soil. (Agricultural run-off in the Midwest is one of the major
sources of pollution—eutrophication—of the Gulf of Mexico.)
This research shows the need to think qualitatively about the components
of ecological systems. Even though the same amounts of nitrogen were applied
to the soil in both the conventional and manure-based systems, the impact
on the soil and the broader environment was qualitatively different. The
manure becomes part of the soil, building it up, while the mineral fertilizer
basically runs through the soil into the plant or out of the soil into
the ground water and streams.
It is somewhat ironic that these articles, which in many ways exemplify
ecological common sense, appear at a time when transgenic (genetically
modified) crops are being heralded by their producers and also many people
in the USDA as the answer to essential ecological and food shortage problems.
One hopes that sound thinking and healthy ecological practices in agriculture
can increasingly counter the onslaught of agribusiness trying to market
its products at all costs.
References
L.E. Drinkwater et al. (1998). "Legume-based Cropping
Systems Have Reduced Carbon and Nitrogen Losses," Nature 396:262-265.
See also introductory article in the same issue: D. Tilman, "The Greening
of the Green Revolution," pp. 211-212.
W.J. Lewis et al. (1997). "A Total System Approach
to Sustainable Pest Management," Proceedings of the National Academy
of Sciences 94:12243-12248. (My thanks to Fred Kirschenmann for calling
my attention to this article.)
Original source: In Context (Spring, 1999, p. 9); copyright 1999
by The Nature Institute
|
