Some of the scars are 100 years old. Piled up in corners or along fence lines, these unsuspecting stacks of boulders tell a story that’s unfolded before -- a tale of people’s determination to turn this land into something more profitable.

Some two billion years ago, glaciers covered parts the Midwest. As they melted, the rocks and debris trapped within the walls of ice were deposited across Nebraska. In part, this is what makes soils east of the 100th meridian (basically, north and south of North Platte) rich and fertile. But it’s also what makes the ground to the west rocky and rough.

Every couple of decades, people try it again. They pile rocks and boulders to clear the land for farming. As lessons and memories of the past fade, they plow rough land, betting things will work out differently from  last time. Modern practices, equipment and technology evolve, but the results don’t change.

On a recent trip across Nebraska and South Dakota, I saw first-hand both old and fresh scars. Some rock piles peeking over the tops of corn or sunflowers, some in plain sight as new fields were prepped for winter and spring planting. These rocks tell a story of what once was in these fields and what will be, particularly if taxpayer-funded incentives continue motivating grassland conversion to crops.

In 1934, the United States witnessed what has been called “the worst man-made ecological disaster in American history.” The Dust Bowl ripped apart the Great Plains, blowing dirt and dust, killing people and livestock  and forcing homesteaders into foreclosure  and off their farms. It was caused by a combination of erratic weather patterns and indiscriminate plowing of grasslands.

Now, 80 years later, it’s happening again. As grasslands are converted to corn, sunflowers and soybeans, Jekyll-and-Hyde weather patterns are becoming the norm: Drought devastated Texas in 2010, 2011 saw massive floods along the Missouri River, and two years later, those same states saw record-setting drought;. Just weeks ago, a freak fall blizzard killed hundreds of thousands of cattle in Nebraska, South Dakota and Wyoming.

Such erratic weather patterns only are magnified by grassland conversion, while putting remarkable stress on the people and resources of Nebraska. But a responsible farm bill that rebalances how our lands are used can keep us from repeating past mistakes while ensuring farmers can support a growing nation.

With the 2013 farm bill under debate, it’s crucial Congress balance crop and ranching subsidies with conservation on working lands. Most land that is suitable for farmland already is being farmed. What’s still in grass usually is marginal, highly erodible or prone to flooding. Those grasslands may be some of the last native prairie and are better left for grazing and wildlife.

Two things Congress needs do to give native prairie a fighting chance:

* If a farmer converts prairie to grow commodities, he or she would receive less in the way of subsidies from taxpayers. The farmer would have to prove that the land will yield a profitable crop and, in the interim, take on the risk of growing crops, rather than having taxpayers subsidize the risk and insurance.

* For the land already in farming, Congress should require farmers receiving taxpayer help to maintain soil and wetlands conservation in exchange for those subsidies.

Rep. Jeff Fortenberry has been a leader in ensuring farming is fiscally and environmentally responsible. As the farm bill is being negotiated, now’s the time to help him and other members of Congress make these a reality.

As Nebraskans who value the grasslands, it’s important our taxes don’t contribute to the loss of this great ecosystem. It’s important we learn from our mistakes and put an end to the growing number of rock piles -- piles that are reminders of what we once took for granted and have lost forever.

Matt Wagner was born in Scottsbluff and graduated from Omaha Westside High School. He now is director of conservation outreach for the World Wildlife Fund, holds a master’s degree in environmental law and policy from University of Denver Sturm College of Law, and is an associate fellow with the University of Nebraska-Lincoln’s Center for Grassland Studies.