For some farmers, harvest season is not complete until the soil has been turned and a fresh blanket of black soil covers the land, ready for the next growing season. The smell of fresh soil and a sense of pride in a freshly tilled field are often the factors driving a farm's tillage system. Is this really the best way maintain and improve soil health and crop productivity?
"Farmers have a love affair with black soil," says Tony Vyn, Agronomy Department, Purdue University. "This love affair keeps farmers from investigating conservation tillage methods that may be more beneficial to the soil and crops, and offer a cost savings. There is a perception, and it's often wrong, that the best way to deal with damaged soil, compaction or rain is deep loosening of the soil and leaving it black."
Minnesota farmer Dave Legvold agrees. Legvold has used strip tillage on his farm since 2006, yet sees very little adoption to the system by his neighbors. "I began my journey with strip till in 2006 through the Conservation Stewardship Program. I agreed to farm using strip till or no till on 600 acres. It took a partnership between the equipment dealer, the banker and the NRCS office to make the initial investment, but we got it done."
Today, Legvold is a strip-till evangelist, sharing his experiences with universities and farm organizations while mentoring others on how to incorporate the tillage system into their crop management program.
Part of Legvold's farming enterprise includes a 700-acre farm owned by St Olaf College in Northfield, Minn. The college's environmental studies students had been watching the decline in soil health on the farmland, so they put farming requirements in place for those wanting to lease the farmland. Legvold's experience with strip till and other conservation practices made him a good fit with the college.
Improved Soil Health
Legvold and the students conducted a variety of studies each year to measure organic matter, aggregate stability, nutrient cycling, biological activity and carbon exchange. Over the years, their monitoring has indicated significant improvements in soil health, which can be attributed to the changes in tillage practices.
Another study conducted over seven years near Albert Lea, Minn., documented how the use of strip tillage had reversed 40 years of soil compaction from a field that was once conventionally tilled.
"Reducing soil compaction is important to soil health, root growth and yields," says researcher and agronomist Steven J. Carlson. "Compaction layers will inhibit plant roots from growing below the layer, which will limit crop yields and increase chances of lodging."
This study measured soil compaction to a depth of 27 inches. The conventionally tilled field had a compaction layer at a depth of 15 inches, while no compaction was found in the strip-tilled field. Additionally, the strip-tilled field had an abundance of earthworms with more than seven times the population found in the conventionally tilled field. Biological activity, including the presence of earthworms, is a key indicator of soil health and positively contributes to soil health as crop residue is consumed and broken down. The resulting soil structure is firm, resists compaction, and increases the soil's ability to hold water and nutrients.
Fabian G. Fernandez, from the Department of Soil, Water and Climate at the University of Minnesota, recently published research comparing soil properties after a five-year study of no till and strip till in the Agronomy Journal. His research demonstrated that tillage systems can have an important impact on soil properties. He and his fellow researchers measured an 8.6 percent increase in soil organic matter along with a 4 percent decrease in bulk density and, within the top 10 centimeters of the soil, an average 36 percent reduction in penetration resistance in strip tillage relative to no till.
Fernandez concludes his research demonstrates that strip till can be used as an alternative conservation tillage system to no till in order to improve soil's physical properties, and suggests that strip till may provide a better environment for root growth and development, which is critical for water and nutrient uptake.
Vyn and his colleagues at Purdue have observed the adaptation and advancements made in strip-till technologies during the past 25 years, and they have also witnessed a transformation of the technology as well as acceptance from growers.
"Far and away, the biggest single improvement has been RTK guidance, which allows precise planting in the center of the loosened zone," Vyn says. " In early versions of strip tillage, farmers relied on eyesight to follow the strip till berm. Once RTK came, farmers could precisely plant in the center and could have strip-tillage machines that were narrower, frequently because of costs, than the planter."
In addition to the technology improvements, Vyn credits the development of fertilizer banding technologies to band dry or liquid fertilizers along with anhydrous ammonia applications as an important change in strip tillage.
"Today, one of the main reasons farmers adopt strip tillage is not just for increased warming and drying for earlier planting opportunities or longer planting window, but for nutrient placement," Vyn says. "We find that in about 60 percent of the cases, nutrient placement is tied to strip tillage, because doing it at the same time as tillage, they derived an increased benefit from a nutrient band positioned relatively close to the intended growth."
Changes in strip-tillage equipment design and precision technology are giving farmers more options when it comes to berm formation, soil loosening and fertilizer placement. The evolution from shank-based row units to vertical tillage rolling coulters helps prevent shank smearing in cold, wet soils and mixes the applied fertilizer throughout the root growth zone.
Iowa farmer, Ben Pederson, found the right fit for his cropping program with a machine that uses a rolling cog wheel, containment coulters and a dry fertilizer application tube. The system uses variable-rate technology to precisely meter nutrients as they are needed across the field and place them into the strip-till zones. The action of the cog wheel and coulters mix the nutrients throughout the tilled profile instead of the typical band.
"I think I may have gotten things right by accident," Pederson says. "The tube shoots the dry fertilizer into the momentary gap as the cog wheel works through the soil. The result is that fertility does get down to 8 inches, but there is some near the surface as well. I believe this provides concentrated, yet strategically placed fertility that the plant has access to at all stages."
Equipment advances resulting in better residue cutting, wider diameter lead coulters and improved row cleaners to move residue from the strip-till zone ahead of shanks or coulters have also made it easier for farmers to use strip till after corn. Typically, strip till has been used in soybean or cereal crops leading into a corn crop, but increasingly more growers are using it in corn after corn or soybeans after corn.
"Farmers are recognizing there are more benefits associated with strip tillage in soybeans as well as corn," Vyn says. "If farmers are doing some tillage, but not too much, strip tillage is an ideal option ahead of soybeans."
Helping Farmers Address Sustainability Issues With Strip Till
With concerns erupting over agricultural runoff in several critical watersheds, many farmers and their input suppliers are looking at ways to bolster sustainability practices. At South West Ag Partners (SW Ag) in Chatham, Ontario, they have designed a new suite of offerings to help their customers meet potentially changing regulations in their geography. In July 2015, SW Ag unveiled their new Sustainable Cropping Systems offering to their customers. At the core of the offering is the addition of strip tillage coupled with their precision ag programs. This fall, SW Ag added a strip tillage and precision nutrient placement service to allow farmers the opportunity to try out strip tillage without making the investment in equipment.
"We are excited to bring this equipment to our customers," says Rick Youlton, marketing manager for SW Ag. "With our custom applicator service, our customers can take advantage of the benefits of zone tillage without incurring the investment in equipment. Additionally, we are incorporating research and data collection with the acres we strip to get a better understanding of the capabilities and expectations we can have with strip tillage."
SW Ag and their agronomy team, including well-known Canadian agronomist Peter Johnson, will be using yield monitoring, soil testing and other measurements to identify how well the practice of strip tillage works in their growing area. Adding a learning component to the offering gives the farmers the chance to learn from one another as they begin incorporating a new cropping practice.
"Momentum is starting to build for strip tillage," Johnson says. "When we have a discussion on strip tillage at producer events, the room is full. The momentum is there. It's the perfect time for retailers like SW Ag to introduce this concept to their growers."
SW Ag points out seven benefits of strip tillage to their growers as they promote the new offerings: Reduced soil erosion, improved soil structure, ideal seedbed, optimal nutrient placement, less environmental impact, comparable yields/better returns, timeliness and efficiency.
This fall, they had 4,000 acres in the strip-tillage program. They will monitor the crops planted in the strip-tillage areas throughout the 2016 growing season to help their customers better gauge the effectiveness.
"From a broader scale, strip tillage resonates on a bunch of levels," Johnson explains. "One of the areas we are focusing on is residue management. We have to keep the soil covered to prevent erosion from wind and water, but even worse is tillage erosion. Here is a system that allows us to retain most of the soil with excellent residue and still plant in a timely fashion."
Vyn's 25 years of research began in Ontario and continued at Purdue. Over the years, he has seen many advancements and adaptations to strip-till systems and knows firsthand the pros and cons of the systems. Today, he believes the need to address soil health and environmental concerns rises to the top.
"I regard strip tillage as a system that is only going to become more dominant with time, in part because of the technical developments and the flexibility of new tools, but mostly because of the need to deal with soil erosion. Strip till gives you the environmental advantage you will never get with full-width tillage," Vyn says.
Yield Drag: Fact or Fiction
For many years, a limiting factor to adoption of strip tillage has been the perception of a yield drag. While yield drag may have been an issue in the early days, system enhancements such as the refinement in RTK guidance and proper nutrient placement have alleviated this concern. Purdue University and the University of Minnesota have conducted research comparing yield data among various tillage systems.
In Purdue's most recent research, Vyn reported that corn yields with strip till were better than both chisel plow and no till when corn followed corn, and about equal to no till when corn followed soybeans. He states that strip-till corn yields usually equal those with the fall disk-chisel system, but this year they surpassed the chisel system by 18.5 bushels per acre when corn followed corn. Seeding into a friable, drier and warmer strip of soil with minimal soil compaction during planting is the key advantage for a fall strip-till system according to Vyn.
"Yields with the strip-till system may have been even higher if we have taken advantage of the earlier soil drying to plant even earlier," Vyn reported. "However, in this research, all tillage systems were planted on the same day. The spring of 2015 was so wet and cool that the fall strip-till system offered a great opportunity for an extended number of planting days between the frequent rain events."
Additionally, the Indiana researchers found that strip till resulted in higher yields than chisel plowing even when no additional nitrogen (N) was applied after the 23 pounds of N starter banded at planting. The relative yield gain for strip till when no sidedress N was applied was especially apparent in continuous corn.
"These results make it abundantly clear that even 40 years of continuous no till do not magically result in more available mineral N in soil for corn to use. It is doubtful that farmers can be successful in no-till corn production systems by using lower N rates than they do in conventional tillage systems, and certainly not when corn follows corn or a grass or cereal cover crop," Vyn explains in his report.
Strip Till Has Challenges but Is Worth a Fresh Look
Tillage practices and cropping programs are as unique and individualized as the farmers running the ground. Like most farm practices, tillage programs are not a one-size-fits-all approach for all soil in every condition.
"Strip tillers still need to address issues like weed control, varying land contours and extreme weather events," Vyn explains. "The biggest constraint for strip till is extreme weather events that limit fall strip-tillage opportunities. Delayed harvest and wet falls are not a good combination for strip till."
Environmental Tillage Systems (ETS), the manufacturer of the SoilWarrior, recognizes the need to be flexible and forward thinking when it comes to equipment design and adaptability.¬≠¬≠¬≠
"While there is not much we can do about the weather and no equipment can run under all field conditions, we can build equipment that is highly adjustable to accommodate most conditions and also help farmers be efficient with their time and resources when they can get in the field," says ETS CEO Kevin Born. "With the right tool, strip tillage is a great option for farmers who want to profitably rebuild their soil."