By Angie Peltier, UMN Extension crops educator, Northwest Research & Outreach Center, Crookston, MN and Jodi DeJong-Hughes, UMN Extension educator, Water Resources Center, Willmar, MN
January 7, 2026’s Strategic Farming: Let’s Talk Crops session kicked off the start of this series of webinars for the year. Hosted by UMN Extension crops educator Angie Peltier, the program featured Jodi DeJong-Hughes, an UMN Extension educator that works for the Water Resources Center and specializes in the impact of tillage practices on crop yield and soil health. This webinar series runs through March.
To watch this episode visit: http://z.umn.edu/StrategicFarmingRecordings.
During photosynthesis, chlorophyll, the green pigment in plants, uses the sun’s energy to combine carbon dioxide and water into glucose and oxygen molecules. Respiration is essentially the opposite of photosynthesis, where plants need oxygen to convert some of the glucose back into energy is used to run the machinery of cells. On a sunny day, more photosynthesis than respiration occurs allowing plants to make the building blocks essential for growth and development and yield. Soil compaction and reduced pore space consequently slows crop growth and development and reduce yield potential. Yield losses of 60% can occur in severely compacted soils, but annual yield losses in the upper Midwest are 15-30% (Voorhees et al. 1989).
Plants growing in compacted soils will often take longer to emerge, can emerge unevenly and often have difficulty closing rows as their growth can be slowed or permanently stunted. One study from Wisconsin (Wolkowski and Lowery, 2008) compared corn seedling growing in soil that had been driven on by equipment with different axle loads of less than 5, 9 and 14 tons per axle to cause different levels of compaction. Three weeks after planting, 90% of the corn crop had emerged in the 5 tons/axle soil, whereas only 40 and 15% of corn seedlings had emerged when soil had been driven on with 9 and 14 ton axle loads, respectively. Although additional seedlings emerged in the more compacted soil over time, as most agronomists will agree, uneven emergence can cause lost yield potential in corn.
In some years, the final corn population in a field can also be impacted by soil compaction. With higher populations tending to occur in the less compacted soil than in a soil with a moderate level of compaction caused by a floatation tire inflated to 36 psi or by road tires inflated to 100 psi (Krmenec, 2000). Compaction impacts on plant populations tend to be more severe in wet growing seasons.
Other nutrient deficiencies are also more common in compacted soils, regardless of how the nutrient is taken up. Water-soluble nutrients such as nitrogen and sulfur are taken up through a process called mass flow. With mass flow, nutrients dissolved in water ‘come along for the ride’ as water is pulled from the soil by roots, exiting through small leaf pores that are opened by the plant to allow gas exchange required for photosynthesis; this process is called evapotranspiration. This process, called evapotranspiration, is more difficult for plants growing in compacted soil.
Compaction slows the rate of root growth and therefore the soil area that can be explored. Nutrients such as iron, phosphorus, potassium and zinc, are not taken up by mass flow but rather diffusion. For diffusion to take place, a root must be in direct contact or within ~1/10 inch of the nutrient. The reduced root length and number resulting from compaction means that fewer roots will be in close proximity to nutrients that need to be taken up by diffusion.
If a person is farming poorly structured soil and practices aggressive tillage, for example disk ripping, chisel plowing or moldboard plowing, axle loads should be around 5 tons to minimize the depth of compaction. However, the ability of the soil to withstand axle load increases with the adoption of soil health practices resulting in more resilient, better structured soil. In this case, say where a person is farming soil with good structure and is either practicing conservation tillage or no-till, axle loads can be as high as ~10 tons with limited compaction, should soils be fit when traveling across the field.
These targets can be difficult to reach for all but the small, specialty crop or hobby farmer with smaller equipment. The large equipment used to produce agronomic crops at scale are getting heavier with each redesign, with the axle load of a single axle, 1,200 bushel capacity grain cart filled to 90% capacity with a 35 to 40 ton axle load, a tandem (tracked) 2,000 bushel grain cart an 75 ton axle load, and a 2,500 bushel, tracked grain cart a 90 ton axle load.
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| Wheel compaction. Photo Jodi DeJong-Hughes |
To watch this episode visit: http://z.umn.edu/StrategicFarmingRecordings.
Well-aggregated soils: key to productive crops
Soil aggregates are sand, silt and clay soil particles and organic matter held together by dead and living soil microbes and the sugary compounds that roots exude into the soil. Surrounding these aggregates are pore spaces of various sizes. Well-aggregated soil tends to be more productive soil as pore spaces provide room for both water infiltration and gas exchange and oxygen, both of which are critical for plant growth and development. Macropores formed by plant roots and earthworms account for ~1% of a soil’s pore space, but 70% of water infiltration. Tillage breaks up macropores, making it much more difficult for water or air to infiltrate the soil. Therefore, compacted soils tend to be wetter soils, and as air warms 10,000 times faster than water, can be slower to warm and dry than uncompacted soils.During photosynthesis, chlorophyll, the green pigment in plants, uses the sun’s energy to combine carbon dioxide and water into glucose and oxygen molecules. Respiration is essentially the opposite of photosynthesis, where plants need oxygen to convert some of the glucose back into energy is used to run the machinery of cells. On a sunny day, more photosynthesis than respiration occurs allowing plants to make the building blocks essential for growth and development and yield. Soil compaction and reduced pore space consequently slows crop growth and development and reduce yield potential. Yield losses of 60% can occur in severely compacted soils, but annual yield losses in the upper Midwest are 15-30% (Voorhees et al. 1989).
Plants growing in compacted soils will often take longer to emerge, can emerge unevenly and often have difficulty closing rows as their growth can be slowed or permanently stunted. One study from Wisconsin (Wolkowski and Lowery, 2008) compared corn seedling growing in soil that had been driven on by equipment with different axle loads of less than 5, 9 and 14 tons per axle to cause different levels of compaction. Three weeks after planting, 90% of the corn crop had emerged in the 5 tons/axle soil, whereas only 40 and 15% of corn seedlings had emerged when soil had been driven on with 9 and 14 ton axle loads, respectively. Although additional seedlings emerged in the more compacted soil over time, as most agronomists will agree, uneven emergence can cause lost yield potential in corn.
In some years, the final corn population in a field can also be impacted by soil compaction. With higher populations tending to occur in the less compacted soil than in a soil with a moderate level of compaction caused by a floatation tire inflated to 36 psi or by road tires inflated to 100 psi (Krmenec, 2000). Compaction impacts on plant populations tend to be more severe in wet growing seasons.
Nutrient uptake also affected by compaction
In legume crops such as clovers, alfalfa and soybean, specialized bacteria called rhizobium form a symbiotic relationship with plant roots. Roots swell to form nodules, the in-plant home for rhizobium bacteria. The plant supplies water and sugars to rhizobium bacteria and in return bacteria convert atmospheric nitrogen into a plant-available form. Poor nodulation can be an indicator of compacted soil as rhizobium bacteria require oxygen to establish this symbiosis, compacted soils that allow less air infiltration tend to limit nodule development in legume crops.Other nutrient deficiencies are also more common in compacted soils, regardless of how the nutrient is taken up. Water-soluble nutrients such as nitrogen and sulfur are taken up through a process called mass flow. With mass flow, nutrients dissolved in water ‘come along for the ride’ as water is pulled from the soil by roots, exiting through small leaf pores that are opened by the plant to allow gas exchange required for photosynthesis; this process is called evapotranspiration. This process, called evapotranspiration, is more difficult for plants growing in compacted soil.
Compaction slows the rate of root growth and therefore the soil area that can be explored. Nutrients such as iron, phosphorus, potassium and zinc, are not taken up by mass flow but rather diffusion. For diffusion to take place, a root must be in direct contact or within ~1/10 inch of the nutrient. The reduced root length and number resulting from compaction means that fewer roots will be in close proximity to nutrients that need to be taken up by diffusion.
How compaction occurs
Soil compaction can occur any time a heavy piece of equipment moves across a field, but there are some factors that increase the probability of it occurring.Soil moisture
Moving heavy equipment or tilling the soil when it is wet causes clay particles to slide around against each other, eventually ending up much closer to one another with fewer pores than before the field operation took place. Most soil compaction actually takes place not immediately after a soaking rain when most wouldn’t even consider getting back into the field, but rather ~3 days after this soaking rain when many think that the risk of causing compaction has passed.Axle load
The weight of equipment carried by a single axle is called an axle load. Research has shown that compaction can be approximately a foot deep when axle loads are below 5 tons, increasing to 2 feet deep when the axle load is 16.5 tons (Hakansson and Reeder, 1994). Research has shown that as a general rule of thumb, each 10 tons of axle load can compact soil ~12 inches deep, with the heavier the axle load, the deeper the compaction.If a person is farming poorly structured soil and practices aggressive tillage, for example disk ripping, chisel plowing or moldboard plowing, axle loads should be around 5 tons to minimize the depth of compaction. However, the ability of the soil to withstand axle load increases with the adoption of soil health practices resulting in more resilient, better structured soil. In this case, say where a person is farming soil with good structure and is either practicing conservation tillage or no-till, axle loads can be as high as ~10 tons with limited compaction, should soils be fit when traveling across the field.
These targets can be difficult to reach for all but the small, specialty crop or hobby farmer with smaller equipment. The large equipment used to produce agronomic crops at scale are getting heavier with each redesign, with the axle load of a single axle, 1,200 bushel capacity grain cart filled to 90% capacity with a 35 to 40 ton axle load, a tandem (tracked) 2,000 bushel grain cart an 75 ton axle load, and a 2,500 bushel, tracked grain cart a 90 ton axle load.
Recommendation
While there are many things about farming that are not within our control, considering equipment axle load (particularly at their heaviest, such as a full grain cart) when making equipment purchases. With heavier axle loads, keeping the equipment on already compacted headlands, field approach or adjacent road can help to reduce the total area of soil at risk of compaction. Adding axles, using tires with a larger footprint and keeping tires inflated properly can also reduce compaction risk.
Ground pressure
Tire selection and pressure can make a large difference on the intensity of the compaction that occurs. Wider side-walled tires allow for lower tire pressure than those with a narrower sidewalls. Research at Ohio State University (Abu-Hamdeh et al., 1995) compared compaction that occurred when tires were properly inflated to ~6 pounds per square inch (psi) pressure to compaction when overinflated to ~24 psi. While overinflated tires resulted in a loss of 85% of the pore space in the top 4-8 (it would be much higher in the 0-4”) inches of soil, properly inflate tires resulted in a 50% loss of pore space. For tracked equipment, wider tracks (3 ft) resulted in a loss of porosity of ~60% and narrower tracks (2 ft) a loss of ~75%. Note that center-fill planters have psi’s as high as 85 to 120.
Tires require higher pressure (psi) when traveling down the road, the tires heat up and can expand, putting the tire at risk of falling off the rim. When traveling much slower -between 4 and 10 mph- while in the field, tire pressures can be lowered as there is much less risk of tire distortion and loss, and lower pressures result in less compaction risk. Properly inflated tires also have improved fuel efficiency, reduce wheel slip, and increase tractor speed which can increase the number of acres covered in a given unit of time.
Several companies produce after-market, automated tire inflation systems (ATIS) that can be added onto a tractor. ATIS can deflate/inflate the triple tires on a tractor and the four on a planter at a time. In addition to reducing both the risks of soil compaction or losing a tire at speed, ATISs can improve fuel economy, cause less wear-and-tear on the tires and improve field trafficability.
There is a common misconception that using tracked equipment rather than equipment with tires always reduces compaction risk. As a general rule, however, the wider the track and the larger the carriage, the less compaction risk with tracked vehicles. With tracked equipment, one cannot simply divide the weight of the piece of equipment by the number of square inches of track touching the ground, as there are inherent pressure points that experience higher pressure than the rest of the track, such as the guide wheels. The average psi of tracks can change based on the number and positioning of the mid-wheel rollers, the stiffness of both the springs at the attachment points and in the track itself, the track and carriage width and weight transfer while towing. Quad tracks are better overall than a single, larger track on either side of the equipment.
Tires require higher pressure (psi) when traveling down the road, the tires heat up and can expand, putting the tire at risk of falling off the rim. When traveling much slower -between 4 and 10 mph- while in the field, tire pressures can be lowered as there is much less risk of tire distortion and loss, and lower pressures result in less compaction risk. Properly inflated tires also have improved fuel efficiency, reduce wheel slip, and increase tractor speed which can increase the number of acres covered in a given unit of time.
Several companies produce after-market, automated tire inflation systems (ATIS) that can be added onto a tractor. ATIS can deflate/inflate the triple tires on a tractor and the four on a planter at a time. In addition to reducing both the risks of soil compaction or losing a tire at speed, ATISs can improve fuel economy, cause less wear-and-tear on the tires and improve field trafficability.
There is a common misconception that using tracked equipment rather than equipment with tires always reduces compaction risk. As a general rule, however, the wider the track and the larger the carriage, the less compaction risk with tracked vehicles. With tracked equipment, one cannot simply divide the weight of the piece of equipment by the number of square inches of track touching the ground, as there are inherent pressure points that experience higher pressure than the rest of the track, such as the guide wheels. The average psi of tracks can change based on the number and positioning of the mid-wheel rollers, the stiffness of both the springs at the attachment points and in the track itself, the track and carriage width and weight transfer while towing. Quad tracks are better overall than a single, larger track on either side of the equipment.
Recommendation
From a compaction standpoint, a properly inflated tire can be just as good as a wide track. Tire pressures set to ~10 pounds per square inch can reduce the risk of deep compaction as it keeps any compaction that does occur in the top . ATISs can quickly inflate and deflate tires during even the busiest parts of the growing season. If you are unwilling (or unable) to adjust your tire pressure from road pressure (for example 30 psi) to the field (~10 psi), wide quad tracks may be your best option for reducing the risk of soil compaction.
Number of passes across field
The first pass across the soil with a tire causes 80% of the compaction that will occur. Coincidentally, in a single growing season, depending upon the number of trips one takes with equipment across a given field, up to 80% of a field’s area could have been traveled and is therefore at risk of compaction. Controlling one’s traffic and traveling in the same wheel tracks across the field can reduce the total square footage of compacted soil. If one prefers to run a grain cart next to the combine to unload on the fly, consider driving the tractor pulling the grain cart in the wheel tracks already caused by the combine. Some companies make after-market canvas material that can be attached to a grain cart to make it easier to run it alongside while driving in the combine’s wheel tracks.
One thing that can naturally help to break up compaction however, is wet/dry cycles in soils that have smectitic clay. Smectite clay tends to shrink in dry conditions, allowing feet-deep cracks to form in the soil, aiding in air and water infiltration. When rain resumes, these cracks are again filled as the clay absorbs water.
Soil structure
Soil aggregates are the top natural defense against soil compaction. One myth that one often hears when coffee shop talk turns to compaction is that Minnesota’s compacted soils don’t stay that way long because of our robust freeze/thaw cycles. Unfortunately, 10-12 freeze/thaw cycles are required in a given growing season for freeze/thaw to help alleviate compaction. In addition, this cycling is unlikely to help alleviate compaction deeper than 2-5 inches as this is where the majority of freeze/thaw occurs in the soil profile.One thing that can naturally help to break up compaction however, is wet/dry cycles in soils that have smectitic clay. Smectite clay tends to shrink in dry conditions, allowing feet-deep cracks to form in the soil, aiding in air and water infiltration. When rain resumes, these cracks are again filled as the clay absorbs water.
How long does compaction last?
Just how long it takes to alleviate soil compaction depends upon how deep compaction is in the soil profile (Sidhu and Duiker, 2006; Hakansson and Reeder, 1994). Should no additional compaction take place, the highly injurious to crop yield potential-compaction in the top six inches of soil (topsoil) can last approximately 5 years. Compaction in the upper subsoil layer (~6-12 inches deep) can last ~10 years and compaction below 12 inches can last even longer. Deeper compaction is harder to remedy as it is not as easily remediated by the freeze/thaw cycle, the wet/dry cycle or deep tillage implements.Alleviating soil compaction
Not every field is blessed with smectitic clay that can shrink in a dry or drought year to perform a natural form of tillage. Even in those fields that do have smectitic clay, there is no guarantee that this natural tillage will be widespread across the field or occur where we need it to and few would hope for a yield-limiting drought to alleviate compaction. There are several practices that can be adopted to alleviate compaction.Reducing tillage to improve both soil health and compaction
No-till is not going to work for every operation or field. However, reducing tillage intensity by using less aggressive implements, reducing tillage depth and making fewer passes across the field will help better preserve soil structure. Perhaps instead of making two passes with a chisel plow in the fall and two with a field cultivator in the spring, consider skipping a pass. Alternatively, if you use a disc ripper at a depth of 11 or 12 inches, consider shallowing tillage depth to 8 inches; similarly, if you are currently ripping at 10 inches, consider shallowing up to 6 inches.
The current farm economy means that there are few that can afford to purchase a new tillage implement such as a strip tiller, that tills just the strip of soil into which the seed is placed, leaving the remaining two-thirds of a field not tilled. But switching from a wider or twisted shovel (which tends to bury more residue but destroys more soil structure) to a narrower, straighter point will reduce the damage to soil structure caused by tillage. Points lift and separate the soil, breaking it up along its natural planes. Disks perform a much more aggressive form of tillage, shearing the soil wherever they meet it, rather than along its natural planes. One way to understand what disks do to the soil is to consider that construction firms use disks to prepare soil to become a roadbed, under which they do not want soil structure-caused pore spaces in the soil.
The current farm economy means that there are few that can afford to purchase a new tillage implement such as a strip tiller, that tills just the strip of soil into which the seed is placed, leaving the remaining two-thirds of a field not tilled. But switching from a wider or twisted shovel (which tends to bury more residue but destroys more soil structure) to a narrower, straighter point will reduce the damage to soil structure caused by tillage. Points lift and separate the soil, breaking it up along its natural planes. Disks perform a much more aggressive form of tillage, shearing the soil wherever they meet it, rather than along its natural planes. One way to understand what disks do to the soil is to consider that construction firms use disks to prepare soil to become a roadbed, under which they do not want soil structure-caused pore spaces in the soil.
Cover crops
Incorporating cover crops (terminated by herbicide or roller-crimper and not tillage) can improve the trafficability in fields and build soil aggregates over time. Research has shown that cover crops can improve soil strength before it collapses under pressure due to compaction; soils in which red clover, ryegrass and hairy vetch cover crops were grown were twice as strong in resisting pressure than either no-till or conventionally tilled soils without cover crops (Shannon Osborne, USDA-ARS). With time, large cover crop plants that form taproots can help to break up plow plan layers.
Mechanical remediation. Efforts at remediating soil compaction with a tillage implement must begin by gathering information, including how wet the soil is, the depth of the compacted layer and where the compaction is within a given field. To precisely identify the depth and severity of a compacted layer of soil, soil scientists, crop consultants and crop producers alike can learn to use a tool called a penetrometer.
Choose to use a subsoiling implement that has a straight shank as curved shanks will tend to lift up and mix the less productive subsoil into the more productive topsoil layer. With the understanding that tractor selection will be key as the deeper the tillage, the more horsepower (30-50 horses per shank!) will be required to pull the tool through the soil at depth, set your points to travel 1 to 2 inches below the compacted layer and then make a single pass. Only work the soil when it is fit (dry enough) to do so and only on those acres that require it (often the lowest areas in the field) to save on fuel costs.
Once mechanical remediation has occurred, avoid driving on the ripped soil or risk undoing the time and expense associated with the ripping you just did. Consider using controlled traffic after the remediation is complete to reduce the risk of having to deep rip once again. If considering switching to no-till, consider deep ripping compaction layers beforehand as there will be no way to remediate compaction without additional tillage.
Research in Iowa showed that alleviating compaction by deep ripping increased yields by a modest 0.5 to 2 bu/A (Blackmer, IA Soybean Assn., 2004) with participating farmers feeling that the yield benefits were not worth the expense. Deep ripping also resulted in unintended consequences including the additional time and expense associated with having to either remove or roll the rocks that had been brought to the soil surface with deep ripping or risk equipment damage.
2. Abu-Hamdeh, N., T. Carpenter, R. Wood, and R. Holmes. 1995. Combine Tractive Devices: Effects on Soil Compaction. SAE Technical Paper 952159. https://doi.org/10.4271/952159
Hakansson, I. and R.C. Reeder. 1994. Subsoil compaction by vehicles with high axle load - extent, persistence and crop response. Soil & Tillage Research 29: 277-304.
Krmenec, A.J. 2000. Vehicle traffic and soil compaction. Poster at Midwest Farm Progress Show, IL.
Sidhu, D. and Duiker, S.W. (2006), Soil Compaction in Conservation Tillage: Crop Impacts. Agron. J., 98: 1257-1264. https://doi.org/10.2134/agronj2006.0070
Wolkowski, R. and B. Lowery. 2008. Soil Compaction: causes, concerns, and cures. University of Wisconsin Extension publication #A3367.
Voorhees, W.B., J. F. Johnson, G. W. Randall, and W. W. Nelson. 1989. Corn Growth and Yield as Affected by Surface and Subsoil Compaction. Agronomy Journal 81: 294-303.
Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council for their generous support of this program!
Mechanical remediation. Efforts at remediating soil compaction with a tillage implement must begin by gathering information, including how wet the soil is, the depth of the compacted layer and where the compaction is within a given field. To precisely identify the depth and severity of a compacted layer of soil, soil scientists, crop consultants and crop producers alike can learn to use a tool called a penetrometer.
Choose to use a subsoiling implement that has a straight shank as curved shanks will tend to lift up and mix the less productive subsoil into the more productive topsoil layer. With the understanding that tractor selection will be key as the deeper the tillage, the more horsepower (30-50 horses per shank!) will be required to pull the tool through the soil at depth, set your points to travel 1 to 2 inches below the compacted layer and then make a single pass. Only work the soil when it is fit (dry enough) to do so and only on those acres that require it (often the lowest areas in the field) to save on fuel costs.
Once mechanical remediation has occurred, avoid driving on the ripped soil or risk undoing the time and expense associated with the ripping you just did. Consider using controlled traffic after the remediation is complete to reduce the risk of having to deep rip once again. If considering switching to no-till, consider deep ripping compaction layers beforehand as there will be no way to remediate compaction without additional tillage.
Research in Iowa showed that alleviating compaction by deep ripping increased yields by a modest 0.5 to 2 bu/A (Blackmer, IA Soybean Assn., 2004) with participating farmers feeling that the yield benefits were not worth the expense. Deep ripping also resulted in unintended consequences including the additional time and expense associated with having to either remove or roll the rocks that had been brought to the soil surface with deep ripping or risk equipment damage.
Audience questions
DeJong-Hughes fielded many audience questions, including: How important are dual front tires on mechanical front wheel drive tractors?, Have you seen any differences using vertical tillage and disks?, How should one alleviate or avoid horizontal compaction layers in the spring?, What type of planter does one need in order to consider making fewer tillage passes across the field?Soil Management Summit
To learn more about soil health practices from other farmers, researchers and crop consultants, next week, on January 14 & 15 UMN Extension’s Soil Management Summit will be held in conjunction with NDSU Extension’s DIRT (Dakota Innovation Research & Technology) Conference at the Delta Marriott Hotel in Fargo, ND.Northern Soil Compaction Conference
For a more granular look at how soil becomes compacted, what factors increase the risk and how best to alleviate it, consider attending the Northern Soil Compaction Conference that will occur on four Tuesday mornings (9 am-noon CST) this February (Feb 3, 10, 17, 24) virtually.Literature cited
1. Abu-Hamdeh, N., T. Carpenter, R. Wood, and R. Holmes. 1995. Soil Compaction of Four-Wheel Drive and Tracked Tractors Under Various Draft Loads. SAE Technical Paper 952098. https://doi.org/10.4271/9520982. Abu-Hamdeh, N., T. Carpenter, R. Wood, and R. Holmes. 1995. Combine Tractive Devices: Effects on Soil Compaction. SAE Technical Paper 952159. https://doi.org/10.4271/952159
Hakansson, I. and R.C. Reeder. 1994. Subsoil compaction by vehicles with high axle load - extent, persistence and crop response. Soil & Tillage Research 29: 277-304.
Krmenec, A.J. 2000. Vehicle traffic and soil compaction. Poster at Midwest Farm Progress Show, IL.
Sidhu, D. and Duiker, S.W. (2006), Soil Compaction in Conservation Tillage: Crop Impacts. Agron. J., 98: 1257-1264. https://doi.org/10.2134/agronj2006.0070
Wolkowski, R. and B. Lowery. 2008. Soil Compaction: causes, concerns, and cures. University of Wisconsin Extension publication #A3367.
Voorhees, W.B., J. F. Johnson, G. W. Randall, and W. W. Nelson. 1989. Corn Growth and Yield as Affected by Surface and Subsoil Compaction. Agronomy Journal 81: 294-303.
Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council for their generous support of this program!
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