The achievement of a record corn yield (393 bushels per acre) by Mr. Francis Childs of Manchester, Iowa, has brought on a record harvest of opinions, both pro and con, about the way in which this yield was achieved. Much of the concern is centered around the use of nitrogen fertilizer.

The Iowa Environmental Council and others question the example set by farmers using exceedingly high rates of nitrogen fertilizer, while several writers have defended the high rate of fertilizer use. They cite Extension-based recommendations and the research paper by Tom Deluca and me that found little change in nitrate concentration and nitrogen output of the Des Moines River basin from 1945 to about 1990. The point in our paper was that row crop agriculture leads to nitrate loss. In early years, the sources were organic; now nitrate in our waters comes much more from fertilizers.

The Des Moines River runs through some of the world's best soils, formed after the glaciers of the last ice age had retreated, and deep-rooted prairie plants and wetlands filled the landscape. The soils that formed were dark and deep, rich in clay and organic matter. Decomposition of organic matter was accelerated, and nitrate was formed.

This is an ideal situation for corn: a deep soil with oxygen, plenty of capacity to hold water and to provide nitrogen for the crop. Nitrate is formed by action of soil bacteria when the soil is warm and moist, and well aerated. This condition also leads to degradation of the soil organic matter, which releases more nitrogen for the nitrification process.

The soil organic matter degrades with or without the corn crop, so nitrate is formed before, during, and after crop growth. Nitrate also is formed from the nitrogen in anhydrous ammonia fertilizer, residues of legumes, manure from farm animals, and any other organic material such as human sewage. Because nitrate moves with the water, much of it ends up dissolved in the water in our ubiquitous tile drains, where it flows out to the streams and finally to the rivers.

In 1945, the state used very little commercial inorganic fertilizer. Much of the nitrogen removed in the corn crop was taken from the soil, and the soil lost as much as half of its organic matter. Thus Iowa groundwater and rivers became rich in nitrate. It is no coincidence that in 1945 the first reports ever of nitrate poisoning (the condition where high nitrate is linked to oxygen starvation of infants) were documented, and these were in Iowa.

Today, the soils still leak nitrate, except when the tile drains do not run. We grow less alfalfa and clovers, nitrogen-fixing forage legumes, the soils are not releasing nearly as much nitrogen, and so the nitrogen needed to achieve the high yields of today's far superior hybrids comes largely from fertilizers and animal manures.

Agronomists have spent their careers trying to slow down nitrate loss. Field experiments have consistently shown that at best about half of the fertilizer nitrogen added in a given year is recovered by that corn crop. Some nitrogen stays in the soil as part of organic matter, some is lost to the atmosphere, and some runs off with erosion in the sediments.

Because of this complicated cycling, it is not possible to give definitive balances of nitrogen. The recommendations used by Extension (1.25 pounds of fertilizer nitrogen per bushel of corn per acre, adjusted for soil and manure nitrogen sources and for management ) are based primarily on economic returns, not environmental concerns.

Importantly, it is the Iowa corn-soybean rotation, while highly productive, that helped bring about nitrate-contaminated groundwater and high nitrate rivers in the first place. The rotation has led to hypoxia in the Gulf of Mexico, and has put the Raccoon and Iowa rivers at the top of the list of watersheds in the United States for nitrate output.

If everyone strived for 400 bushels of corn using twice as much nitrogen fertilizer as they are now using for 200 bushels, more than twice as much nitrogen would be lost to the groundwater and surface waters. And during years when yields were low because of poor weather, even more of this nitrogen will be lost than when perfect weather gives high yields.

If the public wants low nitrate waters, it needs to help redesign the landscapes of Iowa so that less is in corn and soybeans, and more is used to capture and remove the escaping nitrate (such as buffers and wetlands).

Landscapes would become more diverse, smaller farms would thrive, and animal agriculture operations would be smaller and spread throughout the landscape. Food for people (along with feed for animals) would again be grown in Iowa, and the grain would be worth far more because the market is not gutted.

Mr. Childs is trying to be on the cutting edge of the current system. But the system is a sick one. It is a system that rewards bigness, subsidizes bulk grains, and provides little in support, both financial and educational, for those farmers who farm sustainably.

Let's examine our agriculture in terms of what it does for the environment and the people, not just for the marketplace.