@農자료창고

CARROLL, IA. — Iowa farmers plant 2 million to 3 million more acres for corn than they did a decade ago, generating concerns about pollution from nitrogen runoff and soil erosion.

But some farmers are looking for alternatives. Last week about 45 farmers gathered on Art Behrens’ 240-acre farm, which uses a five-year rotation of two years of corn, one of soybeans and two with nitrogen-replenishing, soil-knitting cover grasses.

“We’re stewards of the land, and we need to find our own solutions to erosion and nitrogen runoff,” said Behrens, a veterinarian who returned to his family farm a decade ago and converted it to an organic operation.

Behrens has expanded beyond the two-year, corn/soybean rotation favored by most Iowa farmers to a five-year rotation of contour strip tillage, a conservation practice that mixes cover crops such as rye, barley and alfalfa in with two years of corn and one year of soybeans.

An interested observer at the Behrens farm was Montgomery County farmer Mark Peterson, who this year is trying cover grasses on about one-third of his acres. Peterson isn’t interested in going organic, but he worries about his soil.

“We have rolling terrain in our part of the state, and I got tired of seeing soil erode,” said Peterson, who took pains to describe himself as a “mainstream farmer, not a far-out advocate.”

The matter of soil erosion and nitrogen runoff is engaging policymakers, especially with continued problems with pollution in Iowa’s waterways and the hypoxia dead zone that has emerged at the mouth of the Mississippi River in the Gulf of Mexico.

This month Congress will revisit the farm bill, and an issue will be whether or not conservation practices should be made mandatory as terms for federal subsidies for crop insurance.

A decade ago, Iowa farmers planted an even split between nitrogen-hungry corn and nitrogen-replenishing soybeans — about 11 million acres apiece.

But the boom in ethanol demand, which now chews up 60 percent of Iowa’s corn, has swung the acreage pendulum toward corn. This year Iowa farmers planted about 13.7 million acres of corn and around 9 million acres of soybeans.

Two traditional cover crops, oats and hay, have also lost ground in Iowa. Oat acreage has declined from 290,000 in 2002 to 130,000 acres this year. Hay alfalfa acres have dropped from 1.25 million a decade ago to 800,000 acres this year.

Those expanded corn acres and reduced soybean and cover crops have meant more nitrogen use and more worries about the conditions of Iowa’s waterways.

Throw in continued soil erosion problems, and thoughtful farmers like Behrens and Peterson become anxious for new solutions.

Actually, the use of cover crops is an old one. Before World War II, farmers set aside up to one-third of their land to raise oats for the horses, the prime power on farms until the postwar machinery boom.

The idea of expanded rotations isn’t new, either. A study by Iowa State University last summer showed that a three-year rotation of corn, soybeans and a cover crop could actually enhance farmer profitability. It was the latest in a line of studies and advocacy positions calling for wider rotations.

Behrens’ demonstration of cover crops last week was held under the auspices of Practical Farmers of Iowa, an independent group that advocates greater crop diversity.

“We want to be careful with the word ‘sustainable,’ which is overused in agriculture,” said Sarah Carlson, PFI’s research and policy director. “Farmers are interested in finding ways to increase the diversity of their crops.”

Practical Farmers helps farmers plant cover crops such as rye, barley and clover as well as more traditional cash crops such as oats and alfalfa, all of which replenish soil nitrogen and have deep root systems that fight erosion by knitting the soil tighter.

“We’re really interested in winter grasses that are planted right after harvest, then plowed under in the spring for planting,” said Carlson.

Carlson said that Practical Farmers eschews the policy debate in favor of more field demonstrations.

“You know there will be policy discussions,” she said. “What is important here in Iowa is to show that there are alternatives, and that we can have more diversity in farm fields.”

A key question about rotations has centered on production. Naysayers to more crop diversity argue that any reduction in corn production could result in higher prices that could drive up feed costs for Iowa’s livestock producers, not to mention the state’s 41 ethanol refineries.

The feedstock issue for ethanol is left to federal law, which requires that of the 36 billion gallon target for biofuels to be reached in the next decade, half must come from non-corn sources.

“It is important to expand our thinking to include the small grains that come from cover grasses into animal feed rotations,” Carlson said.