Ecological Agriculture Enters the Mainstream

Craig Holdrege

From In Context #1 (Spring, 1999)

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.)

Seth JordanJanuary 27, 2021