Yield differences from soil tillage are more often the exception rather than the norm. This is particularly the case for soybean yields, as well as rotated corn systems.
Due to the costs associated with soil tillage and the number of extra passes on fields, reducing soil tillage is a great way to cut costs, labor and soil erosion, while promoting soil health and getting the same crop yields.
Farmers see an immediate benefit to leaving crop residues on the soil surface in regions with annual rainfall less than 20 inches due to soil moisture conservation. However, farmers are often reluctant to farm with more crop residue in Minnesota and the eastern Dakotas, where higher precipitation, cool springs and short growing seasons are common.
The primary concern is the potential for slower crop growth and reduced yield due to cooler, wetter soils in the spring. Crop residue management is even more challenging when corn follows corn, or on poorly drained soils with a high clay content.
Higher residue doesn’t mean lower yields
Study 1: Tillage and yield
Research by the University of Minnesota and North Dakota State University showed that reduced tillage systems increased crop residue cover and reduced soil erosion while having a minimal effect on crop yields. These results are often accompanied by lower tillage management costs (equipment, fuel and labor) compared to aggressive tillage systems.
On-farm research was conducted by University of Minnesota researchers from 2010 through 2012 in west-central Minnesota near Clarkfield. They compared four full-width tillage systems with varying crop residue levels in a corn-soybean rotation.
Tillage treatments included the following:
- Strip-till (ST): A fall strip-till treatment consisting of fluted coulter and residue managers, followed by notched coulters that build a 3- to 4- inch berm.
- Vertical-till (VT): Fall vertical-till pass plus a spring vertical-till pass. Either large wavy coulters or a gang of coulters operated at a less-than-4-degree angle.
- Chisel plow/vertical-till (CP/VT) rotation: Fall chisel plow plus spring field cultivation before planting corn rotated with a fall vertical-till pass, plus a spring vertical-till pass system before planting soybeans.
- Disk rip/chisel plow (DR/CP) rotation: Fall disk rip plus spring field cultivation before planting corn rotated with fall chisel plow, plus spring field cultivation before planting soybeans.
Results: Yield and residue levels
The study revealed corn and soybean yields weren’t affected by the type of tillage system, although tillage costs were substantially lower with strip till. However, the type of tillage did affect crop residue levels.
Strip-till retained the highest crop residue cover following both corn and soybean planting, while the chisel plow/vertical-till rotation had the lowest residue levels following corn and soybean planting (Figures 1 and 2).
Results: Costs and profitability
These data show Minnesota growers can increase profitability with reduced tillage (Table 1). In this study, costs per acre for a two-year corn and soybean rotation ranged from $29.20 for strip-till to $48.70 for fall disk rip and chisel plow rotation.
Strip-till saved $19.50 per acre over the DR/CP rotation with no loss in yield. By changing to strip-till, a farmer could save almost $20,000 for a two-year corn and soybean rotation on a 1,000-acre farm.
Table 1: Calculated tillage costs per acre
|Tillage system||Corn year cost||Soybean year cost||Two-year rotation cost|
|Vertical-till (two-pass)||$19.70 per acre||$19.70 per acre||$39.40 per acre|
|Strip-till||$14.60 per acre||$14.60 per acre||$29.20 per acre|
|CP/VT rotation||$20.50 per acre||$19.70 per acre||$40.20 per acre|
|DR/CP rotation||$28.20 per acre||$20.50 per acre||$48.70 per acre|
Study 2: Tillage and yield
Between 2005 and 2012, North Dakota State University conducted small plot tillage studies at three locations in North Dakota and one location in northwest Minnesota.
Researchers found that 76 percent of the time, yield wasn’t affected by tillage when soybean followed corn (Figure 3).
In years when tillage type did affect soybean yield, strip-till had higher yields than chisel plow and no-till. In Carrington, when there was a yield difference, strip-till and no-till had higher yields than aggressive rototilling (Table 2).
Table 2: Average soybean yields for three tillage systems
|Tillage system||Average soybean yield: Fargo (five site-years)||Average soybean yield: Carrington (four site-years)||Average soybean yield: Prosper (four site-years)||Average soybean yield: Moorhead (four site-years)|
|Chisel plow||28 bushels per acre||28 bushels per acre||52* bushels per acre||33 bushels per acre|
|No-till||29 bushels per acre||29 bushels per acre||--||--|
|Strip-till||29 bushels per acre||30 bushels per acre||48 bushels per acre||40** bushels per acre|
*Chisel plow yields were statistically higher in one of the four years.
**Strip-till yields were statistically higher than chisel plow yields in three of the four years.
When tillage treatment has an effect
Results change slightly when growing corn following soybean or wheat. During 18 site-years, corn yield wasn’t affected by the type of tillage 44 percent of the time (Figure 4).
When tillage treatment had an effect, strip-till had higher corn yields than chisel plow and no-till 44 percent of the time. Chisel plow had higher corn yields than strip-till and no-till only 12 percent of the time. In other words, more aggressive tillage only increased yield about one out of every nine site-years.
Results by site
In Fargo, N.D., corn yield wasn’t affected by tillage method four out of the five years (Table 3). Tillage treatments at this site included chisel plow (two passes with a chisel plow and one field cultivation), strip-till and no tillage. The site was on a clay loam soil.
In Carrington, N.D., tillage treatments were aggressive tillage (two fall passes with a roto-tiller and two spring field cultivations), fall strip till, and no tillage on a loam soil in a wheat-corn-soybean rotation. There were no yield differences due to tillage over the five years of the study.
At sites in Prosper, N.D. and Moorhead, tillage treatments included chisel plow (fall chisel plow with a spring field cultivation) and strip-till. During four years at the two locations, strip-till had an average yield advantage of 14 bushels an acre (Table 3).
Table 3: Average corn yields for three tillage systems
|Tillage system||Average corn yield: Fargo (five site-years)||Average corn yield: Carrington (five site-years)||Average corn yield: Prosper (four site-years)||Average corn yield: Moorhead (four site-years)|
|Chisel plow||130 bushels per acre||145 bushels per acre||184 bushels per acre||161 bushels per acre|
|No-till||124 bushels per acre||144 bushels per acre||--||--|
|Strip-till||128 bushels per acre||145 bushels per acre||198* bushels per acre||40* bushels per acre|
*Chisel plow yields were statistically higher than strip-till only in the study’s first year. For the following three years, strip-till yields were significantly higher than chisel plow yields.
If corn was priced at $3.30 a bushel, strip-till resulted in a profit increase of $46 an acre, while reducing the cost of additional tillage passes and maintaining more residue. Researchers surmised that, “the superior soil conditions may have facilitated greater rooting depth in the strip-till treatments and may have contributed to higher yields, especially in drier years”.
In a separate three-year study from 2006 to 2008 in southern Minnesota, University of Minnesota researchers compared soybean yields between chisel plowing plus spring field cultivation, strip-till and no-till for fields previously planted in strip-tilled corn.
Even with the higher residue levels, the type of tillage had no effect on the soybean yields during the three years (Figure 5). This demonstrates soybean adaptability among various tillage systems.
A University of Minnesota tillage study from 2008 to 2011 on poorly drained loam and clay loam soils at four sites (two located at research centers and two located in full-scale farm fields) in southwest and west-central Minnesota compared the effects of three tillage systems on continuous corn yields.
Tillage treatments included moldboard plow plus one or two spring field cultivations (MP), strip-till with a shank (ST), and chisel plow or disk rip plus spring field cultivation (CPDR).
Moldboard plow had the lowest residue levels averaged over the four locations at 13 percent (Figure 6). This residue level isn’t sufficient to protect the soil from wind and water erosion, and is the system with the highest fuel and time requirement of the three tillage treatments.
The chisel plow/disk rip tillage treatment had almost three times the residue level (37 percent) than moldboard plow. It’s considered adequate to protect the soil from erosion and maintain soil productivity over time. Strip-till had the highest level of residue in the continuous corn system at 61 percent soil coverage.
The continuous corn yields with fall strip-till were similar to moldboard plow during the first year but lower in the second and third years, except when a secondary spring strip-till pass was performed to manage the residue and warm the soil (Figures 7 to 10).
Residue in the reduced tillage systems tended to build up in years two and three, and covered the strip-till berm, creating a cooler environment for the seed. A second pass with a lighter, in-line coulter implement helped manage the residue and warmed up the soil similar to moldboard plow (Figure 11). Yields shown in figures 8, 9 and 10 demonstrate this effect.
In 2009, both Cannon City and Morris plots strip-tilled in the fall received a secondary in-line coulter pass in the spring. In 2010, only the Cannon City fall strip-till received the secondary pass in the spring. In 2011, both Cannon City and Morris again received a secondary pass in the spring.
When the second pass was added to strip-till, yields were statistically the same as moldboard plow and disk rip/chisel plow.
Annual weather affects yield more than tillage
An earlier study in 2004 and 2005 across southern and west-central Minnesota compared on-farm corn yields at 13 sites for chisel plowing plus spring field cultivation, strip-till, one-pass spring field cultivation and no-till.
Tillage treatments had a larger effect on corn yields during 2004, when air temperatures were cooler than normal, than during 2005, when air temperatures were warmer than normal (Figure 11).
In a cool spring, corn with no tillage yielded six to nine bushels per acre less than corn that received tillage. However, in a warmer-than-normal year, no-till yielded the same as the other tillage systems.
The benefits of no-till included:
- An average of 2.7 times more residue than chisel plowing with a field cultivation (Figure 11).
- Lower costs per acre for equipment costs, tractor wear and tear and labor.
Averaged over two years, corn yields were similar among the chisel-plowed and strip-tilled fields while strip-till had twice the residue. These results are similar to those observed in long-term small-plot tillage trials in Waseca, where very little differences in yields have been observed among tillage systems in a corn and soybean rotation.
The perception remains that more residue will lower yields, but today's planters and drills have options to handle high levels of crop residue. These include row cleaners and coulters that clear residue from the seed row and ensure good seed-to-soil contact and a warmer seedbed. Equipping the planter with starter fertilizer attachments increases the chance for consistent yields in high-residue systems.
Choosing the best tillage system for your farm isn’t a “one-size-fits-all” decision. It’s similar to selecting hybrids to meet specific conditions and needs. It’s not necessary to leave the field completely covered with residue to improve soil health and reduce soil erosion while maintaining yields.
Evaluating the economics of tillage systems is very complex. Adjust tillage depth and intensity based on field factors such as
- Soil texture
- Internal drainage
- Crop grown
- Previous crop residue remaining
Give consideration to
- The initial and maintenance costs of equipment
- The size of tractor needed to pull the tool
- Equipment depreciation
- Labor costs
- Conservation program incentives
- Increased management costs related to fertilizer and pest management
In addition, there are human factors that influence the choice of tillage system, such as farming and family tradition, age, commodity markets, government programs and neighbor perception.
When selecting a tillage system, it’s important to compare differences in production costs, as well as potential yield differences. Table 4 illustrates four typical tillage options when planting soybeans into corn residue in the upper Midwest, using the 2016 Iowa State University Custom Rate Survey.
One pass of tillage can cost $14 to $21 per acre depending on the implement. When planting soybeans, costs can range from $54.90 per acre for no tillage up to $85.15 per acre for chisel plow plus a spring field cultivation. This represents a $30 per acre difference. With soybeans at $9 per bushel, chisel-plowed fields would need a yield increase of more than 3 bushels per acre to pay for the tillage.
Table 4: Tillage options when planting soybeans
|Operation||No-till||Vertical-till or field cultivation||Chisel plow plus field cultivation||Strip-till|
|Planter (tillage-specific)||$20.15 per acre||$19.90 per acre||$19.90 per acre||$20.15 per acre|
|Primary tillage||$0 per acre||$14.05 per acre||$16.45 per acre||$17.15 per acre|
|Secondary tillage||$0 per acre||$0 per acre||$14.05 per acre||$0 per acre|
|Combine||$34.75 per acre||$34.75 per acre||$34.75 per acre||$34.75 per acre|
|Number of passes||2 passes||3 passes||4 passes||3 passes|
Fortunately, research has shown soybean yields are more consistent across soil conditions and tillage options. This makes no-till a viable and economical option.
Standing stalks in no-till and strip-till maintain more surface residue, which improves water infiltration and minimizes soil erosion. No-till and strip-till farmers that leave standing stalks also lower their harvest costs by not using a chopping head.
However, farmers who have high-residue systems frequently will have residue managers on their planter. This slightly increases the cost over conventional planters.
On the other hand, corn often needs incorporated fertilizers and seedbed preparation in the spring, which requires two to four additional field passes. This adds to the overall fuel costs, labor and wear and tear on equipment.
Table 5 uses four different tillage examples farmers may use when growing corn in the Upper Midwest, and the cost of each pass.
For a majority of the fields with chisel plow, disk rip or moldboard plow systems, fertilizer is broadcast in one pass and then incorporated with a secondary tillage pass in the spring. Strip-till saves a pass by applying phosphorus and potassium (nitrogen where appropriate) in the fall with the strip tiller. Plus, you can apply additional fertilizer with the planter and/or at side dress.
Using the 2016 Iowa State University Custom Rate Survey, strip-till costs $40 less per acre than moldboard plow with two field cultivations in the spring. If corn is priced at $3.30 a bushel, moldboard plow would need a yield increase of 12 bushels to pay for the extra tillage.
Chisel plow and disk rip with one pass of a spring field cultivation had similar rates and cost $25 more an acre than strip till, but $16 less an acre than moldboard plow. Even with the higher residue levels, Minnesota and North Dakota research data shows yields remain similar in a corn-soybean rotation regardless of tillage method.
In some regions, no-till is an option when growing corn, especially on sandier soils or in a rotation with very little residue from the previous crop. Fertilizer and lime are usually broadcast with no incorporation, and nitrogen may be side-dressed after the corn has emerged. The cost for no-till is just over $66 per acre, which is half the cost of the moldboard plow system.
Table 5: Tillage options when planting corn
|Operation||Strip-till||Chisel plow plus field cultivation||Disk rip plus field cultivation||Moldboard plow plus field cultivation|
|Planter||$20.15 per acre||$19.90 per acre||$19.90 per acre||$19.90 per acre|
|Sidedress N fertilizer||$11.15 per acre||$0 per acre||$0 per acre||$0 per acre|
|Broadcast fertilizer||$0 per acre||$4.90 per acre||$4.90 per acre||$4.90 per acre|
|Anhydrous ammonia||$0 per acre||$12.20 per acre||$12.20 per acre||$12.20 per acre|
|Primary tillage pass||$17.15* per acre||$16.45 per acre||$17.80 per acre||$18.80 per acre|
|Secondary tillage pass (first pass)||$0 per acre||$14.05 per acre||$14.05 per acre||$14.05 per acre|
|Secondary tillage pass (second pass)||$0 per acre||$0 per acre||$0 per acre||$14.05 per acre|
|Combine without chopping head||$34.75 per acre||$0 per acre||$0 per acre||$0 per acre|
|Combine with chopping head||$0 per acre||$40.10 per acre||$40.10 per acre||$40.10 per acre|
|Total cost||$83.20 per acre||$107.60 per acre||$108.95 per acre||$124.00 per acre|
|Number of passes||4 passes||6 passes||6 passes||7 passes|
*Strip-till price includes the cost of applying fertilizer with the strip tiller. In continuous corn, strip-till may need an additional lighter tillage pass in the spring to “freshen” the berm at a cost of $11.00 per acre.
Reducing tillage means fewer trips across the field, conserving fuel, time and labor, and cutting machinery maintenance. The power requirement and fuel used for tillage equipment varies depending on
Number of row units
Shank or disk depth
Fuel use rises with tillage intensity, depth and increased number of passes. Effectively pulling aggressive tillage implements, such as a disk ripper or moldboard plow, requires that tractors use lower gears and consume more fuel. Using a lighter, less aggressive tillage implement can save fuel costs by operating the tractor in higher gears.
In a 2013 study at Iowa State University, fuel use reduced 18 to 34 percent when operating the tractor in a higher gear and at a reduced engine speed while maintaining travel speed.
In the same ISU study, raising disking depth from 5 inches to 3 inches saved 6 percent in fuel use. However, dropping tillage depth from 9 inches to 18 inches in continuous corn almost doubled fuel use, with no added yield advantage.
Another way to lower fuel costs is to eliminate a primary tillage pass or two secondary tillage passes.
In a 2015 study, researchers compared fuel usage with different tillage implements (Table 6). Moldboard plowing with two passes of a spring field cultivator would use 546 gallons more diesel ($1,910 at $3.50 per gallon) than a shallow disking and 406 gallons more diesel ($1,420 at $3.50 per gallon) than strip-till over 1,000 acres.
Table 6: Fuel use and cost
|Operation||Fuel use per 1,000 acres||Fuel cost per 1,000 acres: $3.50 a gallon||Fuel cost per 1,000 acres: $2.50 a gallon|
|Shallow disking||35 gallons||$123||$875|
|Field cultivation||73 gallons||$256||$1,825|
|Moldboard plow + 1 field cultivation||508 gallons||$1,778||$12,700|
|Moldboard plow + 2 field cultivations||581 gallons||$2,034||$14,525|
In 2015, researchers from the University of Manitoba partnered with the Prairie Agricultural Machinery Institute to calculate the cost of four tillage systems. The study compared
- Two passes with a double disk (DD)
- Two passes with vertical-till at a 6-degree angle (high-disturbance or VT 6)
- Two passes with vertical-till at 0 degrees (low-disturbance or VT 0)
- One pass with strip-till (ST)
All were pulled by the same tractor, on a sandy loam soil in corn residue. Residue levels after tillage were more than 60 percent for strip-till and low-disturbance vertical-till and under 30 percent for double disk and high-disturbance vertical till.
There were no differences in soybean yield due to tillage (data not shown). The study could use tractor and tillage costs alone to calculate a total cost per acre.
Both vertical-till units could effectively run at a higher speed compared to either the strip-till or double disk. This equated to more acres tilled per hour by vertical till, with 7 more acres an hour than strip-till, and 10 more acres per hour than double disk (Figure 12).
Fuel usage ranged from 1,020 gallons to 1,540 gallons over 1,000 acres, with strip-till using the least amount of fuel (Figure 13). This is due to effective corn residue management with only one pass of the strip-till equipment. Strip-till used 34 percent less fuel than high-disturbance vertical till.
Across Minnesota and North Dakota, almost half of cropland is being rented by the operator. More than 74 percent of that land (23 million acres across Minnesota and North Dakota) is owned by landlords who have limited to no connection to the land (Table 7).
Table 7: Rented crop acreage statistics for Minnesota and North Dakota
|State||Total cropland||Rented cropland||Rented cropland owned by non-farmers||Rented cropland owned by non-farmers|
|Minnesota||26 million acres||45%||78%||8.1 million acres|
|North Dakota||39.3 million acres||49%||74%||14.3 million acres|
Generally, land owners that have a stake in the land’s earning potential have more of an interest in soil health and conservation practices. A Utah State University study of absentee owners of farms or wooded acreage found that absentees express high environmental concern, especially those who used the land for recreation.
When asked whether conservation is important on their property, 88 percent responded yes to soil, 56 percent said yes to wildlife and 66 percent said yes to water. However, the land owner may not be knowledgeable about their options or how to find programs or farmers who share their goals.
While farmers and landowners may have conflicting views regarding conservation and production practices, using no-till or strip-till improves the long-term productivity of the soil and can represent both environmental and economic benefit for the land. It’s worth a conversation with the land owner about the benefits of reduced tillage for preserving their land legacy.
Bigelow, D., Borchers, A., & Hubbs, T. (2016). U.S. farmland ownership, tenure, and transfer (EIB-161). United States Department of Agriculture Economic Research Service.
DeJong-Hughes, J. & Vetsch, J. (2018). On-farm comparison of conservation tillage systems for corn following soybeans.
Franzen, D., Chaterjee, A., & Cattanach, N. (2013). Long-term tillage studies in Fargo-Ryan silty clay loam soils in the 2011-2012 crop year. In 2012 Sugarbeet Research and Extension Reports, Fargo, ND: Sugarbeet Research and Education Board of Minnesota and North Dakota.
Hanna, M., & Schweitzer, D. (2015). Farm Energy: Case Studies - Techniques to improve tractor energy efficiency and fuel savings (Iowa State University Extension PM 3063D).
Nowatzki, J., Endres, G., DeJong-Hughes, J., & Aakre, D. (2011). Strip till for field crop production: Equipment, production, economics.
Petrzelka, P., Ma, Z., & Malin, S. (2013). The elephant in the room: Absentee landowners and conservation management. Land Use Policy, 30, 157-166.
Plastina, A., Johanns, A., & Wood, M. (2016). Iowa State University custom rate survey (A3-10).
Randall, G., Evans, S.D., Lueschen, W.E. & Moncrief, J.F. (1987). Tillage best management practices for corn-soybean rotations in the Minnesota River basin.
United States Department of Agriculture National Agricultural Statistics Service. 2012 Census of Agriculture.
Walther, P.A. (2017). Corn (Zea mays L.) residue management for soybean (Glycine max L.) production: On-farm experiment (master’s thesis), University of Manitoba.
Upper Midwest Tillage Guide is a collaboration between University of Minnesota and North Dakota State University.
Peer review provided by Richard Wolkowski, emeritus Extension soil scientist, University of Wisconsin-Madison.
Reviewed in 2018