Photo courtesy of Iowa Soybean Association
SOIL HEALTH PARTNERSHIP | ALL RIGHTS RESERVED © 2017
Tim Smith thought he was doing everything right. But conservation programs, like the Soil Health Partnership, opened his eyes to new methods of mitigating erosion and managing nutrients. This includes use of cover crops, including cereal rye and oats. “Farming is always evolving,” Smith says.
Tim Smith remembers farming on his family’s North Central Iowa farm on a John Deere Model A two-cylinder tractor. It had 25 horsepower.
Smith still farms that land today, but farming technology has evolved in ways he couldn’t imagine sitting in that open-seat tractor alongside his father. Today, his tractor is not only much more powerful, but, equipped with a GPS steering system, much more precise.
Smith says one thing hasn’t changed: “Even with the most modern technology, productivity still comes back to our precious soil. Rocket science can’t help you if your soil is of poor quality.”
The evolving practices on his farm eventually led him back to that soil. Living in the Boone River Watershed, Smith had heard about high levels of nitrates found in stream water, and he wondered why.
“I always thought I was doing everything pretty good in terms of nitrogen stewardship, but it turned out I had room for improvement,” Smith said.
In 2011, he decided to sign up for a Natural Resources Conservation Service project, the Mississippi River Basin Initiative. The federal program had identified Smith’s watershed as a priority for seeing if different farming practices could reduce nitrate and phosphorous levels in the Gulf of Mexico. With financial incentives first attracting him to the program, Smith installed a bioreactor, practiced nutrient management, and started growing cover crops.
Planting a Cover Crop: Cereal Rye
Smith began planting cereal rye as a winter cover crop, at first on just 300 acres.
Planted in late August or early September in his standing crops, the deeply rooted rye helps take up the nitrate left behind from his corn and soybean crops. Smith kills the rye in spring before he plants corn, but leaves the plant residue in the field to help build organic matter as it slowly decomposes over the summer. The slow decomposition of rye residue and mineralization of organic matter then release the nitrogen back into the new crop over time.
“I did some biomass sampling and found 30 pounds of nitrogen in the rye,” Smith says. “That was my first realization that these crops have value. At the time, 30 pounds of nitrogen was worth 50 cents a pound, or about $15 an acre.”
The financial incentives may have started Smith on his journey to new methods, but he quickly realized even more compelling reasons. A combination of switching to strip-till (with similar benefits to no-till) and cover crops has improved the overall profile of his soil.
Smith points out that in heavy rain, a cover crop will greatly mitigate soil erosion. He also says it is a “no-brainer” for cattle farmers, who can let their animals graze on the cover crop or harvest the forage for feed.
He admits that there is a learning curve with starting any new practice.
“You’ve got to pay attention to it. With rye, you have to terminate it before you plant corn in
particular,” he said. “I try to terminate it at least two weeks before I plant corn.”
A dry year followed by two wet springs in a row made demonstrating his early results challenging, but he says his nitrate levels were lower than the stream that his tile drains into. In fact, by years two and three of the MRBI project, his peak nitrates levels were half of the stream’s peak levels.
Joining the Soil Health Partnership
Thanks to his efforts, in 2014 Smith was nominated for the first Good Stewardship Award from the National Corn Growers Association. Then the technical advisor for the Soil Health Partnership, the Nature Conservancy, invited Smith to join the SHP project.
“I was excited to join the Soil Health Partnership because of the emphasis on data collection,” Smith said. “Documenting the benefits will help promote the practices.”
Smith says it’s good that SHP Demonstration Network Farms will test for at least five years, because farming has a huge range of variables. It’s also more effective for spotting trends.
In addition to rye, he has expanded to other species, like oats, hairy vetch and radishes, in different combinations.
“I have seen the benefits of the cover crops with my own eyes, and I’m a believer,” Smith said. “I’m adding a growing crop during a barren time. Nature isn’t barren. There should almost always be something growing. I’m adding two more months of living plants growing in the soil.”
Smith says because of each growing season’s unpredictability, he hasn’t really changed his nitrogen applications. What has changed is that the cover crops help store excess nitrogen that might otherwise be lost to leaching.
Under the SHP, which began in 2014, Smith will continue to take soil samples every year for measurable results. He has a dedicated SHP Field Manager under the program, and a team of agronomists works to ensure scientific standards are met.
“I now realize more than ever how important preserving our soil is,” Smith said. “Roots growing down deep help microorganisms have something to live on. It complements the strip-till, which leaves more residue.”
Today, Smith plants cover crops on 550 out of his 800 acres.
“My goal is long-term sustainability,” he said. “Losing precious soil is not sustainable. If we keep eroding the good soils, we’ll be down to nothing. It’s important to remind farmers of this. A lot of farmers think they don’t have erosion, but in heavy rains, every drop has the potential to take soil with it.”
He points out that 150 years ago, Iowa had about 14 inches of top soil. Now the state, on average, is down to 8 inches, losing the majority of it during the last 50 years, he suspects.
“Among farmers, some are becoming more aware of this,” he said. “We’ve also got entities, like the Des Moines Water Works and Environmental Protection Agency, putting pressure on agriculture, which farmers would like to avoid.”
Smith speaks at many meetings and conferences, and tells farmers that it’s not hard to change practices. He shows photos of his father using a moldboard plow years ago, and points out that at one time, “…we thought we couldn’t farm without a plow.”
“Some farmers don’t like change, but farming practices are always evolving,” Smith said.
Contact Tim Smith.