LAPORTE, Ind. - Porter Township farmer Keith Gustafson is spending his fall as most farmers do.

He's harvesting his crops.

As he reaps his corn and soybeans, however, he's also watching as new plantings - clover, wheat and even more soybeans - start to grow. That's because Gustafson, like a growing number of farmers in Indiana, has returned to planting a second round of crops in the fall. Those crops, left through the winter, are called cover crops.

Although the idea is not new, scientists and farmers have started to realize cover crops, combined with no more tillage of the land, can solve problems that have plagued farms and the environment, including erosion and the leaking of fertilizers into local water systems.

Gustafson, who also serves as supervisor for the Porter County Soil and Water Conservation District, has used cover crops for about four years and said he's already seeing benefits. The field easily absorbed nearly all of a recent heavy rain - roughly 5 inches.

"That just perked down into the soil real well," Gustafson told the Post-Tribune (http://bit.ly/1cOrkth ). "There was hardly any runoff."

Cover crops used to be the norm. Farmers would plant them in fall, leave them in over winter and then kill them off before planting their cash crops. The dead plants would fertilize the ground. Then new technology and science, such as the now-common fertilizer nitrogen, came in during the 1950s. It greatly improved crop yields, said Eileen Kladivko, a professor in Purdue University's Agronomy Department, and cover crops slowly fell out of use.

"(Before), you couldn't just go buy nitrogen in a bag at the local store," she said. "But after World War II, nitrogen became readily available."

The new technologies brought their own problems, however. Too often, heavy rains would wash nitrogen away, polluting local water systems leading to Lake Michigan and the Mississippi River. Lost nitrogen also wasted farmers' money.

Water runoff has been aided by tilling, which can also cause soil erosion. Tilling compacts the soil, making it hard for water to penetrate.

Moving away from tilling has helped solve part of this problem. So have cover crops; their roots draw water into the soil, said Dan Perkins, a certified crop adviser and watershed coordinator for the Jasper County Soil and Water Conservation District.

Perkins has been studying the fields in Jasper County that use cover crops and has found roots going down about five feet. Deep roots help draw water deeper into the soil, creating a moisture reserve and providing protection for summer crops during droughts, such as the one farmers experienced last year.

"That's a huge benefit," he said.

Besides helping with water retention, Kladivko said, cover crops improve overall soil quality.

Midwestern soil developed over thousands of years to a rich quality that proved a boon for growing food. But that high quality has declined ever since people started farming the land.

"What is being realized now is there's this whole other part of the equation to getting maximum yield, and that's soil biology," Perkins said. "Our soil isn't just this lifeless medium that we put fertilizer and herbicide on and we get a crop out of that."

For instance, the soil can pick up beneficial carbon compounds from the roots of the cover crops. The roots also pick up nutrients from fertilizers. Kladivko said even the best farmers who use all the best practices still lose nutrients from their fertilizers during winter; cover crops can stop that.

"It's a natural system that's leaky," she said. "There's no bottom to it."

The cover crops act as a slow-release fertilizer because the soil gets those nutrients back as the plants decompose.

Overall, as soil health improves, it's possible farmers can, after a number of years, cut back on fertilizers, especially if they include legumes - a good source of nitrogen - as a cover crop. They can also possibly use fewer pesticides, as some cover crops crowd out weeds.

Not only the federal government but also environmental groups like the National Resources Defense Council and National Wildlife Federation champion cover crops and no-till.

Gustafson said he learned about cover crops after state and federal officials started advocating them and he saw some of Perkins' videos on the topic. Along with seeing the water soak into the ground, he's seeing less soil erosion, he said.

Jasper County farmer Dave Rodibaugh also has started experimenting with cover crops. He's used them about four years on 10 percent to 15 percent of his farmland and said he likes that he could improve both the quality of the land and his crop yields.

Although Rodibaugh said he doesn't have any evidence yet of improvement in either area, Perkins said he's heard anecdotal stories about other farmers seeing improved yields.

If that can be substantiated, and if soil quality improves, "we get the best of both worlds," Perkins said.

When he started focusing on cover crops four years ago, they were planted on just 250 acres in Jasper County. This year, he knows of at least 6,000 acres being planted and thinks the number could reach 10,000.

Those increases are in line with the state's average, which has quadrupled in the past few years.

"The interest has really skyrocketed," Kladivko said.

In fact, Indiana led the country last year, with a million acres of cover crops planted, according to the Natural Resources Conservation Service.

Even with the growth, however, cover crops are still a small minority in Indiana. The 1 million acres last year is less than 10 percent of the 13 million acres of farmland in the state.

If cover crops are so beneficial, why don't more farmers plant them? For starters, they cost money and take time. Rodibaugh said he pays $30 to $40 an acre to plant cover crops, and at 2,000 acres, that adds up. He also plants them immediately after harvesting a field, and that is already a chaotic time.

The time of harvest also plays a role. If cover crops are planted too late, they don't have time to grow before frost sets in, so they do little good.

"You're kind of at the mercy of the weather and crop development," Rodibaugh said.

Farmers can seed the crops by plane, but that takes money and, again, depends on the weather. A good rain will help the seeds grow, but dry weather means they might not grow for a while. In Gustafson's case, electrical lines hang over many of his fields; a plane could hit them.

The benefits of cover crops can also take years to develop, Kladivko said, so some farmers hesitate to make the initial investment. Others who rent fields might not feel compelled to spend money improving fields they won't use long-term. Finally, some farmers just don't see a need. Crop yields are rising anyway; can cover crops help enough to justify the cost?

She remains optimistic, however, that more and more Indiana farmers in the state will plant cover crops.

After all, she said, advocates don't want farmers to give up modern technologies and products. Instead, they encourage farmers to use those along with cover crops and no-tilling as the best ways to increase crop yields while also helping the environment.

"I anticipate we'll continue to work with them and try to expand their use," Rodibaugh said.