Much of the land surrounding Larry Ness' 2,850 acres of crops is rangeland. That's because south central South Dakota's Buffalo County top soils are a thin layer overlying shale and gravel.
In addition to challenging soil conditions, Ness plans his corn and soybean crops around late spring, early summer rains and searing late summer temperatures that can quickly extract moisture from soil and plants.
Eleven irrigation pivots ease his moisture issues, but Ness also started no-tilling in 2005 to help retain moisture and maximize the potential of the area's low quality soils.
"There's a wide variety of soil across my fields," Ness says. "Most fields lie along the Missouri River, close to the bluffs there. For thousands of years, gumbo washed down the bluffs and onto that land. It's greasy when it's wet, hard as a rock when it dries out. The farmer I share equipment with, Steve Breding, and I have explored different aspects of no-till for the past 10 years. It's working better than conventional tillage, but we're still looking for the right combination of crop rotation, fertility and soil quality."
Some of Ness' land is relatively flat, with slopes range from 0 to 6%. Other fields can range from 2-15% slopes. Approximately 18 inches of rain falls over summer. Winter brings some snow, but frequent windy conditions generally push snowfall into isolated drifts, leaving much of the soil bare and vulnerable to erosion.
Ness and Breding use a John Deere 1770NT planter to plant corn. They drill soybans with an 1890 John Deere air drill.
"When we started using no-till we were primarily searching for something to help with drought conditions," Breding says. "In 2005 we planted corn into bean stubble and beans into corn stalks. We had some difficulty cutting through irrigated corn stalk residue. We were using the standard down pressure on our planter. We now use a precision air system with increased down pressure, which has resolved that problem."
Since 2005, Ness has planted corn at 32,000 to 34,000 plant populations. In areas where he believes soil has improved through use of no-till, he will increase plant populations to between 35,000 and 37,000
Ness and Breding worked with agronomist Kevin Rabern, who identified Goss's wilt in their corn in 2010. Goss's wilt is a bacteria that can overwinter in soil if it gets a foothold in corn residue. The pathogen can cause two major types of symptoms: a systemic wilt and leaf blight. The leaf blight phase of the disease is the most common and can cause development of lesions with wavy margins similar to some other diseases. Two characteristics distinguishing Goss's wilt from other diseases are dark green to black spots and a leaf surface "ooze." The water-soaked spots are sometimes called freckles because of their appearance. The dried ooze may glisten and appear shiny, similar to varnish.
Residue serves as the primary source of Goss's wilt infection for future crops. The bacteria won't infect new crops unless hail, sand blasting or heavy wind injures the corn leaves. The pathogen can also be seed borne and seed transmitted, but transmission to seedlings has been demonstrated at low rates and is not believe to be a major source of infection except as it provides inoculum for introduction of the disease to new locations.
"For a couple of years we tried baling and selling corn residue to help overcome that disease and reduce our trash issues at planting time," Breding says. "For the past couple of years we've kept residue on the fields because we want the ground cover and nitrogen it provides. We don't graze our stalks because we don't want to risk damaging our soil structure. After several years of leaving the residue on the field, we're seeing reduced erosion and improved soil organic matter buildup with each successive growing season."
Ness and Breding added wheat the crop rotation, looking to add some diversity. They weren't satisfied with the results and backed away from wheat for a few years, but will add it to the rotation again in 2015.
"We also experimented with alfalfa under the pivots," Ness says. "Our crop was successful enough, but getting marketing it to buyers was time consuming. At the time, prices weren't high enough to net enough per-acre income to make it a feasible endeavor."
Breding applies fertilizer to Ness' crops all in one pass at planting, placing it right below the seed in the furrow. That dry product is 46-0-0. A June liquid sidedress – 28-0-0- - is applied at 8 gallons per acre.
It didn't take long for Ness to see an increase in corn yields. With the first season of no-till planting, he harvested 10% more corn.
"I can't attribute 100% of that increase to no-till though," Ness says. "I used a newer hybrid, and my guess is that the yield was bumped up by the combination of no-till and improved genetics."
So far, soybean yields have remained pretty static in Ness' no-till system. He plants 170,000 to 150,000 seeds per acre on irrigated land and 150,000 seeds per acre on dryland. A pattern of scant late summer rainfall has probably affected the crop. Rabern believes soybean yield will begin climbing as soil organic matter builds.
"We've seen slight increases because soil water holding capacity is increasing with no-till," Rabern says. "Once soil organic matter reaches a higher level it will give soybeans access to the water in the soil profile at that critical August stage of maturity."
At harvest, Breding runs the soybean flex head as close to the ground as possible, leaving short soybean stubble. With corn, the combine's residue chopper runs at the highest possible speed in order to distribute residue as evenly as possible.
Ness has seen weed issues reduce with each year of no-till. Roundup aids in pre-emergence control. Herbicide blends using Triple Flex and Roundup help manage any surviving weeds.
"We want to learn more about cover crops and how they could fit in this system," Ness says. "One fall we flew a mix of radish and turnip onto some irrigated corn and beans in September, but that didn't turn out well. The fields were some of my heaviest gumbo. We thought the soil might benefit from the covers but we didn't get a good stand. We'll keep working to find a successful cover crop strategy."
In recent years, cool wet springs have tested Ness and Breding's commitment to no-till as they have often watched neighbors plant under conventional tillage while they waited for soils to warm and dry.
"We intend to keep learning and exploring our options," Ness says. "Things may not always turn out the way we want but we'll keep learning what works and what doesn't."
Sorensen is from Yankton, S.D.