During the 2014 harvest, the Berger family reached a milestone. “We harvested our first 300 bushel per acre corn,” Steve Berger says. “Dad radioed me from the combine cab, telling me he was seeing 320 to 350 bushels showing up on the yield monitor as he progressed through the field.”

The corn had been planted into a cereal rye cover crop on this Washington County, Iowa, operation. “That means we can grow good cover crops while also producing top yields in our cash crops,” Steve says. “It is our goal to do both.”

The journey toward sustainable high yields has been a long one at this farm, located near Wellman, Iowa. Steve and his wife, Julie, and his parents, Dennis and Janice Berger, operate the farm. The family’s first no-till field was planted nearly 40 years ago, and the entire farm was 100% no-till by 1990. Cover crops (primarily cereal rye) have been used for more than 10 years.

“The majority of our farm has been continuously no-tilled for 36 years,” Steve adds. “It has been a learning process, and we have stuck with it. The soil structure changes very slowly over time, becoming more and more resilient. We are starting to see the advantages pay off.”

Southern drift plain

The Berger farm sits in the scenic Southern Drift Plain, a geological feature where glacial deposits have swept into rolling hills that form the familiar southeast Iowa landscape. While the family operates some bottomland adjacent to the English River that is as flat as a tabletop, some of their hill fields are steeply sloped.

Protecting the soil has long been a priority for this fourth-generation farm. “Dad was involved in conservation right from the start,” Steve says. “Building terraces was something we did every year, going back to the 1960s. Over time, we have installed 14 miles of tile-inlet terraces.”

The concept of no-till farming next caught the family’s attention in the mid-1970s. After studying the practice, they decided to try it on one field in 1978—and that field has been farmed without tillage ever since.

“When we first started no-tilling, we did it because it left residue on the surface, which helps stop soil erosion,” he says. “At that point, we didn’t have a clue about the changes that were going on below the soil surface.”

At that time, researchers were just beginning to study some of those changes in the soil. Important substances such as glomalin, known as the soil’s “superglue,” would not be discovered until decades later.

Adding organic matter

The Berger family soon identified organic matter as one of the important subsoil factors that could be influenced by management. The Bergers operate 2,200 acres evenly divided in a corn/soybean rotation. Even with no-till and miles of terraces, the Bergers didn’t think their soybean residue provided enough protection for the soil surface.

“We weren’t controlling all erosion,” Steve says. “And we found we were only maintaining organic matter overall, losing some in the soybean year of the rotation.”

In the 1990s, the Berger family installed yield monitors and began to see how organic matter could affect a crop. “We would be in a corn field, and when we would cross an old fencerow, we would see that yield monitor jump 20 to 30 bushels,” Steve says. “At first, we couldn’t understand why that fencerow had such an increase in yield. Then we went back and soil-tested those areas, and found they were running 6% organic matter. That’s what it was when the settlers came here to the Southern Drift Plain 150 years ago.”

Crop fields in the area now typically show organic matter in the 2.5% to 3% range. “We have oxidized a lot of organic matter, losing soil carbon, over the past century,” Steve continues. “We have basically lost half our soil’s potential. We know, as farmers, that we cannot allow this to go on.”

To turn the tide and slowly rebuild soil organic matter, the family now boosts soil with a combination of cover crops and manure applications.  

The Bergers plant a cover crop on every acre. “We typically use a no-till drill to plant cereal rye into corn and soybean fields following the combine,” Steve says. “If it looks like we are going to have adequate fall moisture, we may aerially seed into standing corn on some fields ahead of harvest.

 “We find that cereal rye is very hardy and germinates easily on some of the poorer soils on our hills,” he continues. “It has excellent root growth. When we dig soil pits, we can trace roots down 30 to 40 inches. Rye also provides good cover in the spring to stop soil erosion. It is our go-to cover crop.”

The Bergers also apply manure in an annual rotation as scheduled by their manure management plan. Steve and a partner use the manure from a 20,000-hog farrow-to-finish operation that he and a partner established in 1993. In addition, the Bergers also bring in some locally available turkey manure.

“The no-till, cover crops and manure work really well together to build organic matter,” Steve says. “It can be tricky trying to get the seeding done in the fall and timing the manure application in the spring to match the growth of the rye, but there is a definite benefit to making it all work.”

By using cover crops, the Bergers are moving away from injecting manure in favor of surface applications. “Most of the microbial processes are taking place just below the soil surface, in that first inch of depth,” Steve explains. “After you use no-till and cover crops for a few years, your soil structure and infiltration rates improve to the point that the soil can absorb more of that manure. It soaks away into the cover crops.”

Using no-till, cover crops and manure, Steve estimates that their organic matter is improving at the rate of about one-tenth of a percent per year. “That is exciting,” he says. “Building soils while maintaining yield is one of the most satisfying things we can do.”

Eye on the English River

As organic matter builds, soil tilth improves and water infiltration rates go up, Steve points out. The soil’s ability to incorporate heavy rainfall is a critical factor, as the farm’s entire acreage drains into the English River watershed. Floods on this and other eastern Iowa rivers have been more frequent and intense in recent years.

“As soil structure becomes more resilient, fields can handle those 2-inch rains that seem to be coming our way more often,” Steve says. “Getting that water into the soil is better than having it run off and fill the river.”

The English River Watershed Management Authority (WMA) was established in 2013 to help find solutions to flooding as well as reduce the amount of nutrients that are entering the Mississippi River watershed. Steve is a board member of this newly formed WMA. “These local watersheds are a good thing, because it is easier for a farmer to take ownership of a concern when they realize that what is coming off their farm directly impacts the watershed,” he says. “On our farm, we are starting a project with the Iowa Soybean Association to test the water coming out of our tile lines for nitrate. We want to establish a baseline to see what is entering the watershed.”

The Berger family tradition of environmental stewardship even extends to the farm’s new shop, which is heated and cooled by an energy-efficient geothermal system.

“Our family has always been influenced by Aldo Leopold’s land ethic,” Steve says. “The Berger family approaches farming not only as a business but also as a science and an art.”