By Jean Caspers-Simmet
St. Olaf College's crop land is a working farm for Dave Legvold, who leases the ground, and is a living laboratory for students. The students learn from Legvold, and he learns from them.
Legvold and biology and environmental studies professor Kathleen Shea's students shared how he and the Northfield, Minn., college have cooperated to bring dead soil back to life as part of the "Building Farmer Wealth with Soil Health" workshop at the Iowa Power Farming Show.
Legvold, a retired teacher and John Deere "technology guy" who began leasing the St. Olaf farm in 2004, refers to the moldboard plow as "one of the great soil destroyers." The ground had been in continuous corn for 30 years.
"It had been moldboard plowed with large amounts of anhydrous ammonia applied and organophosphate bug killers were used to keep insects at bay," Legvold said. "The biological life of the farm was in tough shape."
Megan Gregory, who Legvold describes as "98 pounds dripping wet but smart as a whip" devised a project in 2003 to analyze what was happening on the St. Olaf farm. The plowed ground had low organic matter and high soil density.
"I remember picking Megan up from her dorm and she was dejected," Legvold said. "She thought there was something wrong with her soil sampling method. She found no bugs in the St. Olaf ground. We went to the no-till field and it was teeming with life."
Gregory described the St. Olaf land as "a ground-up formica table top, not much going on." Significant soil erosion had taken place.
To get better soils, farmers need to pay attention to soil drainage, Legvold said. Well drained soils are a must.
"If we control and address soil water problems, we are able to reduce tillage, which leads to increased organic matter, more biological life, more soil porosity and aggregate stability," Legvold said.
He strives to keep big chunks of residue on the soil surface. He doesn't use a chopping corn head. Critters come up to the surface through worm holes to get residue.
"Good soil looks more like a piece of chocolate cake than a handful of chocolate cake mix that has been pulverized," he said.
His main soil quality analysis tool is a spade.
"Digging around in your soil is the first step to soil quality," he said.
Legvold uses a Soil Warrior, a strip-till machine built in Faribault, Minn.
"I can plant corn on corn and I can run through the field right after the combine and it (Soil Warrior) never plugs up," Legvold said.
He applies phosphorus and potassium in the fall. St. Olaf wants no fall-applied nitrogen and no soil-applied insecticide.
"I put the field to bed with the zones in place for the next season," Legvold said. "It creates a nice little berm, 8 to 9 inches deep and 6 inches wide, where you can count on having a good planting environment."
Students Doing On-Farm Research
St. Olaf has been doing on-farm research for many years with projects building on previous years, said student Kate Seybold. The focus is on conservation tillage, nitrogen management and cover crops. Students collect soil samples in June, July and September to look at soil moisture, organic matter, bulk density and water infiltration. They also analyze samples for nitrates, ammonium and phosphates. They collect stalks for stalk nitrate analysis in the fall, and at harvest they look at yield data and calculate profits.
A comparison of strip-till versus conventional tillage demonstrated that soil restoration takes time, Seybold said.
"A single strip-till year won't give you the soil structure and porosity that you want," she said.
In a field that had been strip-tilled for about nine years and had to be conventionally tilled last year because it was tiled, she found that organic matter declined from just one year of tillage.
St. Olaf wants to apply the right amount of nutrients, Seybold said. Extra nitrogen ends up in waterways and it's also a waste of money.
She looked at four nitrogen treatments ranging from 70 to 230 pounds per acre as well as the effectiveness of a nitrification inhibitor. Results showed the inhibitor increased the ability of the soil to hang onto nitrogen but it only paid off at the 130 pound nitrogen rate. Yields and profits were similar for all plots from 70 to 230 pounds.
"If you're looking to improve nitrogen management in a way that is better for the environment and your pocket book, an inhibitor might be helpful, but better yet, don't apply an excessive amount of fertilizer," Seybold said.
Cover Crops Effective
St. Olaf student Connor McCormick, who grew up on a beef farm near Caledonia, Minn., had no experience with cover crops until he learned about them in Shea's agroecology class. He persuaded his dad to try 30 acres of cover crops, which were aerially seeded late last summer. McCormick also worked with a farmer near Faribault on a cover crop planted into standing corn study. His research showed a variety of seeding methods and mixes produced good stands and none caused yield drag.
Next year, students will look at spring- and summer-seeded cover crops. For treatments interseeded in July, they will study how cover crops influence water coming off the field. They will also look at stand density, yields and profits.
Try One Thing
Legvold urges farmers to try one thing each year to improve soil quality. Using less tillage is a good first step. He supports farmers doing their own research quoting a retired farm magazine editor, "If farmers don't do on-farm research, they're going to be at the mercy of those who have the research."
"It's movement,'' Reich said. "Any movement is a positive thing.''