Upper Midwest Tillage Guide
Economics of tillage
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- Higher residue doesn't mean lower yields
- Annual weather affects yield more than tillage
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
Corn and soybean yields in a corn-soybean rotation
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, labor) compared to those for aggressive tillage systems.
On-farm research conducted by University of Minnesota researchers from 2010 through 2012 in west-central Minnesota compared four full-width tillage systems with varying crop residue levels in a corn-soybean rotation. Tillage treatments included the following:
- ST - Fall strip till: fluted coulter and residue managers, followed by notched coulters that build a 3- to 4- inch berm.
- VT - Fall vertical till pass plus a spring vertical till pass: either large wavy coulters or a gang of coulters operated at less than a 4-degree angle.
- 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.
- 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.
The study revealed that corn and soybean yields were not 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 for following corn and soybean planting (Figures 1 and 2).
These data show that 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 $20,000 for a 2 year corn and soybean rotation on a 1,000 acre farm.
Table 1. Calculated tillage costs per acre of four different tillage systems in a corn-soybean rotation near Clarkfield, MN.
|Tillage system||Corn year||Soybean year||2-year rotation1|
|cost per acre ($)|
|Vertical till (2-pass)||19.70||19.70||39.40|
|1Costs include tractor, fuel, labor, depreciation on new implements, parts and repair.|
Figure 3. Soybean yield response to tillage for 17 site years across three locations in North Dakota and one location in Minnesota when soybeans follow corn, 2005-2012.
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, where soybean followed corn, yield was not affected by tillage (Figure 3). In the years where tillage type did have an effect on 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 roto-tilling (Table 2).
Table 2. Average soybean yields for three tillage systems at four locations in North Dakota and Minnesota, 2005-2012 (Nowatzki et al., 2011).
|Average soybean yield|
|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 3 of the 4 years.
Figure 4. Corn yield response to tillage for 18 site-years across three locations in North Dakota and one in Minnesota, 2005-2012.
The results change slightly when growing corn following soybean or wheat. During 18 site years, corn yield was not 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, whereas 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.
In Fargo, ND, the tillage treatments 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. Four out of the five years in Fargo, corn yield was not affected by tillage method (Table 3). At Carrington, ND the 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, ND and Moorhead, MN, the tillage treatments included chisel plow (fall chisel plow with a spring field cultivation) and strip till. During the four years at the two locations, strip till had an average yield advantage of 14 bushels an acre (Table 3). 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" (Franzen et al., 2013).
Table 3. Average corn yields for three tillage systems at four locations in North Dakota and Minnesota, 2005-2012 (Nowatzki et al., 2011).
|Average corn yield|
|bushels per acre|
|*Chisel plow yields were statistically higher than strip till in only the first year of the study. For the following three years, strip till yields were significantly higher than chisel plow yields.|
Figure 5. Average soybean yields and surface residue for four tillage systems near Jeffers, Minnesota, 2006-2008.
*Soybean yields were not significantly different due to tillage treatment.
In a separate 3-year study during 2006 to 2008 in southern Minnesota, UMN 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.
Corn yields in continuous corn
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).
Figure 6. Average residue levels for three tillage systems for 15 site-years across west central and southern Minnesota.
Moldboard plow had the lowest residue levels averaged over the four locations at 13 percent (Figure 6). This level of residue is not 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 level of residue (37%) than moldboard plow and is 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 7-10).
Figure 7. Average corn yields for three tillage systems at three locations in west central and southern Minnesota, 2008.
*Corn yields were not statistically different from each other except at Lamberton, where chisel plow and moldboard plow had a higher yield than strip till. Cannon City was not able to be harvested due to blow-down of corn.
Figure 8. Average corn yields for three tillage systems at four locations in west central and southern Minnesota, 2009.
*Cannon City and Morris received a secondary tillage pass in the strip till plots. At Heron Lake and Lamberton, strip till had significantly lower yields with one pass of strip till and moldboard plow had higher yields than chisel plow and strip till.
Figure 9. Average corn yields for three tillage systems at four locations in west central and southern Minnesota, 2010.
*Cannon City received a secondary spring tillage pass in the strip till plots. At the other three locations, moldboard plow had a higher yield than strip till and higher than disk rip at the Morris location.
Figure 10. Average corn yields for three tillage systems at four locations in west central and southern Minnesota, 2011.
*Cannon City and Morris received a secondary spring tillage pass in the strip till plots. Statistically, moldboard plow had a higher yield than strip till with one pass at the Heron Lake and Lamberton locations.
Photo: Dave Franzen, NDSU
Photo 1. Residue build-up in strip tilled continuous corn managed with a lighter, in-line coulter implement.
It was observed that the residue in the reduced tillage systems tended to build up in years 2 and 3 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 (Photo 1). Yields shown in figures 8, 9, and 10 demonstrate this effect.
In 2009, both Cannon City and Morris fall strip till plots 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. And in 2011, both Cannon City and Morris again received a secondary pass in the spring. When the second pass was added to strip till, the yields were statistically the same at 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).
Figure 11. Average corn yields and surface residue for four tillage systems and 13 site-years in southern Minnesota, 2004-2005 (DeJong-Hughes and Vetsch, 2007).
*In 2004, no-till had yields significantly lower than the other tillage systems (LSD = 3 bu/ac) with no tillage affect in 2005.
In a cool spring, corn with no tillage yielded 6-9 bushel per acre less than the 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), and cost less per acre for equipment costs, tractor wear and tear, and labor.
Averaged over the 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 at Waseca, MN, where very little differences in yields have been observed among tillage systems in a corn and soybean rotation (Randall et al., 1987).
While the perception remains that more residue will lower yields, today's planters and drills have options to handle high levels of crop residue, including 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.
Tillage costs when growing soybean
Choosing the best tillage system for your farm is not a "one-size-fits-all" decision. It is similar to selecting hybrids to meet specific conditions and needs. When it comes to improving soil health and reducing soil erosion while maintaining yields, it is not necessary to leave the field completely covered with residue.
Evaluating the economics of tillage systems is very complex. Depth and intensity of tillage should be adjusted based on factors such as the field’s slope, soil texture, internal drainage, crop grown, and previous crop residue remaining. Consideration must be given to the initial and maintenance costs of equipment, the size of tractor needed to pull the tool, equipment depreciation, labor costs, conservation program incentives, and 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.
It is important to compare differences in production costs when selecting a tillage system, as well as potential yield differences. Using the 2016 Iowa State University Custom Rate Survey, Table 4 illustrates four typical tillage options when planting soybeans into corn residue in the upper Midwest. One pass of tillage can cost $14-21 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 $9 per bushel, chisel plowed fields would need over 3 bushels per acre increase to pay for the tillage.
Table 4. Cost of equipment options and number of tillage passes using four management options when planting soybeans.
|Tillage options when planting soybeans|
|Operation||No-till||Vertical till or field cultivation||Chisel plow + field cultivation||Strip till|
|costs per acre ($/a)|
|Planter (tillage specific)||20.15||19.90||19.90||20.15|
|Number of passes||2||3||4||3|
Fortunately, research has shown that soybean yields are more consistent across soil conditions and tillage options making 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 cost of harvest by forgoing the use of a chopping head. However, farmers who have high residue systems frequently will have residue managers on their planter, which increases the cost slightly over conventional planters.
Tillage costs when growing corn
On the other hand, corn often needs incorporated fertilizers and seedbed preparation in the spring, which requires 2 to 4 additional field passes. This adds to the overall fuel costs, labor, and wear and tear on equipment. The table below uses four different tillage examples farmers may use when growing corn in the upper Midwest and the cost of each pass (Table 5).
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 and additional fertilizer can be applied 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. With corn 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, MN and ND 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 sidedressed after the corn has emerged. The cost for no-till is just over $66 per acre, which is half the cost of the moldboard plow system.
Table 5. Cost of equipment options and number of tillage passes using four management options when planting corn.
|Tillage options when planting corn|
|Operation||Strip till||Chisel plow + field cultivation||Disk rip + field cultivation||Moldboard plow + field cultivation|
|costs per acre ($/a)|
|Sidedress N fertilizer||11.15||0||0||0|
|Primary tillage pass||17.15*||16.45||17.80||18.80|
|Secondary tillage pass (1st pass)||0||14.05||14.05||14.05|
|Secondary tillage pass (2nd pass)||0||0||0||14.05|
|Combine w/o chopping head||34.75||0||0||0|
|Combine w/ chopping head||0||40.10||40.10||40.10|
|Number of passes||4||6||6||7|
|*Strip till price includes the cost of applying fertilizer with the strip tiller. In continuous corn, ST 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 the equipment design, number of row units, components used, soil properties, shank or disk depth, field conditions, and operator adjustments.
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 must 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 was reduced 18 to 34 percent when operating the tractor in a higher gear and at 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, Hanna and Schweitzer 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) than a shallow disking and 406 gallons more diesel ($1,420) than strip till over 1,000 acres.
Table 6. Fuel use and cost per 1,000 acres when using five different tillage options (Hanna and Schweitzer, 2015).
|Fuel cost per 1,000 acres|
|gal/1,000 acres||$ per 1,000 acres|
|Moldboard plow + 1 field cultivation||508||1,778||1,270|
|Moldboard plow + 2 field cultivations||581||2,034||1,453|
In 2015, researchers from the University of Manitoba partnered with the Prairie Ag 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), and 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 over 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). Therefore, this study was able to use tractor and tillage costs alone to calculate a total cost per acre.
Figure 12. Acres tilled per hour using a work rate efficiency of 80 percent for four tillage systems on sandy loam soil near MacGregor, Manitoba. (Adapted from Walther, 2017)
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.
Figure 13. Fuel usage in gallons for four tillage systems on a 1,000 acre farm near MacGregor, Manitoba (Adapted from Walther, 2017).
Another way to reduce fuel usage is to lessen the aggressiveness of the implement. By reducing the angle of the gang from 6 to 0 percent on vertical till, 260 gallons less fuel was used (17% reduction). While this research was conducted on a sandy loam soil, other studies have shown that the higher the silt or clay content, the higher the draft forces, and fuel usage can increase.
When comparing tillage systems, keep in mind the cost of fuel per implement pulled, the depth of the implement, and the number of passes across the field. Small savings can add up across each field.
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 (National Agriculture Statistics Service, Bigelow et al and Petrzelka et al).
|State||Total cropland||Rented cropland||Rented cropland owned by non-farmers|
|acres||percent (%)||percent (%)||acres|
|Minnesota||26 million||45||78||8.1 million|
|North Dakota||39.3 million||49||74||14.3 million|
Generally, land owners that have a stake in the earning potential of the land 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 land owners 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 is worth a conversation with the land owner about the benefits of reduced tillage for preserving their land legacy.
In summary, 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 means to cutting cost, labor, and soil erosion while promoting soil health and obtaining the same crop yields.
Bigelow, D., A. Borchers, T. Hubbs. Aug 2016. U.S. Farmland Ownership, Tenure, and Transfer, EIB-161. Economic Research Service/USDA.
DeJong-Hughes, J., J. Vetsch. 2007. On-farm comparison of conservation tillage systems for corn following soybeans. University of Minnesota Extension publication BU-08483. Available on-line at http://www.extension.umn.edu/agriculture/soils/tillage/on-farm-comparison-of-conservation-tillage-systems-for-corn-following-soybeans/
Franzen, D., A. Chaterjee, N. Cattanach. 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, Sugarbeet Research and Education Board of Minnesota and North Dakota. NDSU Extension Service, Fargo, ND.
Hanna, M., D. Schweitzer. 2015. Farm Energy: Case Studies - Techniques to improve tractor energy efficiency and fuel savings. Iowa State University Extension PM 3063D.
Nowatzki, J., G. Endres, J. DeJong-Hughes, D. Aakre. 2011. Strip Till for Field Crop Production: Equipment, Production, Economics. North Dakota State University Extension Service AE-1370 (Revised). Available on-line at https://www.ag.ndsu.edu/pubs/ageng/machine/ae1370.pdf
Petrzelka, P., Z. Ma, S. Malin. 2013. The Elephant in the Room: Absentee Landowners and Conservation Management. Land Use Policy. Vol. 30: 157-166.
Plastina, A., A. Johanns, M. Wood. 2016. Iowa State University Custom Rate Survey A3-10. Available on-line at http://www.extension.iastate.edu/wright/news/custom-rate-survey-and-cash-rental-rates
Randall, G., S. D. Evans, W. E. Lueschen, and J. F. Moncrief. 1987. Tillage best management practices for corn-soybean rotations in the Minnesota River basin. University of Minnesota Extension. Available on-line at http://www.extension.umn.edu/agriculture/soils/tillage/tillage-best-management-practices-for-corn-soybean-rotations/#yield
United States Department of Agriculture, National Agricultural Statistics Service. 2012 Ag Census. Online at: www.nass.usda.gov
Walther, P. A. 2017. Corn (Zea Mays L.) residue management for soybean (Glycine Max L.) production: On-farm Experiment. M.Sc. 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, Extension Soil Scientist, Emeritus, University of Wisconsin-Madison