Modern farming yields bountiful fields of dreams

July 25, 1996|By Dennis T. Avery

CHURCHVILLE, Va. -- A new report from the World Resources Institute invites us to expect a world with ''storm-battered islands of biological diversity'' in a sea of humans, as wildlands give way to farm, pasture and settlements.

The environmentalists are right that food production is the biggest danger to our wildlife.

The world's cities take up only 1.4 percent of the global land area. Nine billion people in 2040 will occupy only about 3.5 percent of the land area. One-third of the land on this planet is used for farming.

To avoid plowing up more wildlife, we will need to triple today's yields on the world's existing farmland. Can that be done?

Paul Ehrlich and Lester Brown say "No." But they said it could not be done in 1965 and we have already done it.

In fact, the world is full of people who do not know how modern farming has already tripled the world output, but who are firmly convinced we cannot do it again.

The pessimists' favorite argument is that agriculture is up against the law of diminishing returns. But history says the law of diminishing returns may not apply to farming -- yet.

When man first started growing crops, he had to find a way to keep weeds from drowning out the wheat and millet.

The first real answer was a method known as "clean fallow." The farmer left half of his field unplanted for a whole season and pulled out any weeds that sprouted. Then he planted. But that wasted half the cropland.

By the early 20th century, American farmers controlled their weeds with horse-drawn ''cultivators,'' which had pointed steel shoes that tore out the weeds between the crop rows. Corn was ''check-planted,'' enabling the horse to pull the cultivator both between and across the rows. This let the farmer get most of his weeds -- but he could plant only about 5,000 plants per acre.

Growing crops takes nutrients out of the soil. In the old days, the only ways to put them back (and keep the farm from ''wearing out'') were crop rotation and adding manure. Rotation crops such as clover and alfalfa added nitrogen and organic matter to the soil; but a field growing clover was not growing grain.

Nor did crop rotation and manure put back very high levels of nutrients into the soil. Crop yields were limited to between 25 and 30 bushels per year.

Crop rotation was also the only insect control. The better the farmer's corn crop, the more insects he could expect to attract.

With these constraints, a Corn Belt field in the 1920s could grow only two corn crops and a wheat crop every seven years. That made for an average year's yield of perhaps 13 bushels of grain per acre.

Today, a farmer does not need to check-plant his field when he can control his weeds with chemical weedkillers.

Nor do the corn rows have to be wide enough for a horse. Many farmers are planting 25,000 corn plants per acre. A seed company in Michigan says it is testing a variety that can thrive even if crowded in at 50,000 plants per acre.

High levels of plant nutrients result from using available manure with chemical fertilizers. The chemicals provide more soil nutrients per acre than farmers ever got from green manure crops.

The fields have plenty of organic matter because a corn crop that is producing 175 bushels of corn also produces lots of stalks to till back into the soil.

Integrated pest management uses crop rotation, timing and a variety of chemical pest-killers to keep insect damage down to tolerable levels.

Today's Corn Belt farmer can grow big crops of corn, wheat and soybeans almost every year. In seven years, he might grow three 175-bushel corn crops, two hefty soybean crops and one crop of 80-bushel wheat. That is equal to 109 bushels of grain per acre per year -- eight times the yield of the 1920s.

What about the future? What if these high-yield plant populations are protected with supplemental irrigation systems for the occasional dry spell? And with inbred pest-control from genetic engineering? The farmer could well produce 300-bushel corn yields!

Maximum yields

A Dutch researcher calculated 30 years ago that the maximum edible crop yield per acre was between 6 tons and 9 tons (depending on distance from the equator). The world's current average corn yield is only about 2.5 tons, and the average rice yield is 3.5 tons.

The American Corn Belt farmer (at 4.5 tons) has reached only half this theoretical maximum.

We cannot, of course, repeal the law of diminishing returns. But there seems to be quite a bit of room within the statute to feed a projected peak human population of 9 billion to 10 billion people.

We need to increase investments in high-yield agricultural research, and encourage chemical companies to develop new pesticides, with new methods to prevent buildup of resistant pests.

We need free trade in farm products, to use the world's best farmland wherever it lies.

If we do, the global future should feature islands of high-yield farming and high-rise human habitation amid virtually the same wildlands we have today.

Dennis T. Avery is editor of Global Food Quarterly and was formerly the State Department's senior agricultural analyst.

Pub Date: 7/25/96

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