Subsoiling

When Biological Methods Fail

Ideally, soil biology prevents and reverses compaction. Earthworm burrows create continuous vertical channels. Plant roots—especially deep tap-rooted species in diverse mixes—penetrate and hold open pore spaces. Fungal hyphae secrete glomalin that binds soil particles into stable aggregates. Increased organic matter acts as "glue" holding structure together. When these biological processes are active, soil maintains or improves structure without mechanical intervention.

However, on severely degraded land, biology may be unable to initiate this recovery. Compaction from decades of heavy equipment (combines, tractors on wet soil), continuous grazing that doesn't allow pasture recovery, or intensive row-cropping that leaves soil bare and unprotected creates dense, anaerobic hardpans 15-30 cm (6-12 inches) deep. Water infiltration drops below 0.5 inches per hour (1.3 cm/hour)—meaning most rainfall runs off as erosion rather than entering soil. Root penetration stops at the hardpan. Without roots penetrating deep or water carrying oxygen down, anaerobic conditions dominate, making the compacted zone inhospitable to earthworms and most beneficial soil life.

Attempts to establish cover crops on such land often fail or produce weak growth because roots cannot penetrate to access water and nutrients below the hardpan. The few hardy species that establish can't produce enough root biomass to significantly improve structure. Earthworms, if present at all, remain in the surface few inches and cannot create deep channels through the compacted layer. This creates a vicious cycle: biology can't improve the soil because compaction is too severe, but compaction won't improve without biological activity.

Research on severely degraded grazing land in Australia, abandoned row-crop fields in the US Midwest, and compacted sub-Saharan African agricultural land shows similar patterns: after 3-5 years of attempted biological remediation (cover cropping, reduced livestock pressure, adding compost), severely compacted sites showed minimal infiltration improvement (from 0.3 to 0.5 inches/hour), while one-time tillage followed by intensive cover cropping achieved infiltration of 1.5-2.5 inches/hour within 2 years. The difference: mechanical intervention created initial conditions allowing biology to work.

Temporary Disturbance for Long-Term Function

Deep tillage creates instant but temporary improvements. Immediately after subsoiling, infiltration increases dramatically—water can flow into the fractures created by the ripper shanks. Roots can follow these cracks downward, accessing water and nutrients previously unavailable. However, without follow-up biological activity, these improvements disappear. Soil slakes back together within 1-2 years, often returning to conditions as bad as before tillage if living roots don't maintain the cracks and organic matter doesn't stabilize new structure.

This is why immediate cover crop establishment is non-negotiable. Within 48 hours of tillage, diverse cover crops (10+ species including deep tap-rooted plants like daikon radish or forage turnips, fibrous-rooted grasses, and nitrogen-fixing legumes) must be seeded. These plants exploit the improved conditions: roots penetrate deep through the opened channels, depositing exudates and organic matter throughout the disturbed profile. As cover crop roots grow and die, they create permanent channels lined with carbon and colonized by beneficial microbes. Over 1-2 growing seasons, this biological activity begins rebuilding the structure that tillage destroyed, but now with living roots maintaining pathways and organic matter stabilizing aggregates.

Earthworm populations, decimated by tillage (studies show 50-80% mortality from mechanical disturbance), begin recovering within 3-6 months if cover crops provide food and habitat. By year 2-3, earthworm numbers often exceed pre-tillage levels because improved soil conditions (better infiltration, more organic matter, less compaction) create favorable habitat. Mycorrhizal networks, similarly disrupted by tillage, recolonize over 1-2 growing seasons, assisted by the diverse plant community that includes mycorrhizal-dependent species.

The goal is measurable recovery within 2-3 years. Infiltration should reach 2+ inches/hour (5+ cm/hour), indicating functional pore space and biological activity. Soil organic matter should increase 0.3-0.5% from baseline, reflecting ongoing root deposition and microbial activity. Earthworm populations should reach 5-10 per shovelful (approximately 55-110 per square meter), showing restored habitat. Visual soil structure (using spade tests) should show defined aggregates with visible root channels and earthworm burrows. These indicators confirm that biology has taken over structure-building, allowing permanent transition to no-till management.

Regenerative Systems Fit

This type of deep, one-time tillage occupies an uncomfortable but pragmatic position in regenerative systems. It explicitly violates Principle 1 (minimize soil disturbance) and is therefore unacceptable as an ongoing practice. Its use is reserved as a last-resort intervention to break severe, deep compaction that biological methods alone cannot remedy, distinguishing it from shallower, secondary tillage used for seedbed preparation. However, it can enable Principles 2-5 on severely degraded land where they otherwise couldn't function:

Enabling Principle 2 (Maximize Diversity): On severely compacted soil, only a handful of hardy plant species can establish. After tillage allows diverse cover crops to succeed, plant diversity increases from 3-5 species struggling to survive to 10-20+ species thriving. This botanical diversity translates to increased soil biological diversity.

Enabling Principle 3 (Keep Soil Covered): Compacted bare ground that resists plant establishment becomes productive enough to maintain year-round living cover or mulch after one-time tillage breaks the compaction barrier.

Enabling Principle 4 (Maintain Living Roots): Hardpan preventing root penetration below 15 cm (6 inches) limits the season and depth of living root activity. Breaking the hardpan allows roots to penetrate 60+ cm (24+ inches), maintaining biological activity throughout the profile.

Enabling Principle 5 (Integrate Livestock): On compacted land, livestock often cause further degradation because plant recovery is too slow between grazing events. After restoring function, rotational grazing can be implemented without causing recompaction (if managed properly with adequate rest periods).

The key is viewing this as a one-time transition tool, not an ongoing practice. It creates conditions where regenerative management becomes possible, then steps aside. Farms successfully using this approach report transitioning from dysfunctional compacted land to fully regenerative no-till systems within 3-5 years, with the tillage event becoming a historical footnote rather than an ongoing management requirement.

Integration with other practices is critical for success. One-time tillage must be paired with: (1) Diverse cover cropping (absolutely essential for biological recovery), (2) Elimination or dramatic reduction of the compaction-causing practice (lighter equipment, reduced livestock pressure, adequate rest periods), (3) If applicable, transition to controlled traffic farming to prevent future compaction, (4) Commitment to permanent no-till following recovery. Without these complementary practices, tillage provides only temporary relief followed by return to degraded conditions.

For regenerative farmers, the decision to use one-time tillage should trigger serious self-examination: Why did the land reach this state? What management failures led to such severe compaction? How will those be prevented going forward? The practice works only if it's paired with honest assessment and correction of the root causes. Otherwise, it's merely postponing inevitable re-degradation.

Sources behind this view

Videos & Podcasts

• Preventing bare soil and addressing compaction are critical for healthy soil biology, gas exchange, and water infiltration. Deep ripping followed by biological applications and cover crops is recommen

  How to Remove Compaction, Manage Nitrogen, and Build Soil Health Fast with Tainio and John Kempf (opens in new window) | Jump to 2:16 (opens in new window)
  

• Achieving regenerative agriculture requires addressing soil compaction, which hinders gas exchange and biology. Deep compaction needs mechanical removal, followed by cover crops and biologicals to pre

  Antimicrobial Agriculture (opens in new window)
  

• Adopting regenerative practices should start small and incrementally, focusing on soil health over short-term yields. Collaboration, strategic nutrient sourcing, and leveraging resources like Continuu

  Regenerative Ag Reality (opens in new window) | Jump to 30:37 (opens in new window)
  

• Minimizing tillage (mechanical disturbance) is key in regenerative agriculture because it preserves soil structure, worm and root channels, and prevents carbon loss. Building soil resilience over time

  Regenerative Agriculture: key principles, no-till & cover crops (Andrew Randall) (opens in new window) | Jump to 2:44 (opens in new window)
  

Community

• Strategic use of one-time tillage on dense cover crops can accelerate soil regeneration to achieve 12 inches of rich soil in two years or less, enhancing microbial activity and organic matter, and can

  Read more (opens in new window) permies.com

Research

• Reclamation of an Ultisol Damaged by Mechanical Land Clearing (opens in new window)

  This study found: Deep tillage (chisel plow, subsoiling) effectively reclaimed compacted Amazonian soil, dramatically increasing water infiltration and crop yields for rice, soybeans, and corn compared to no-till metho

• Building Soil Health and Fertility through Organic Amendments and Practices: A Review (opens in new window)

  This study found: Review of organic amendments (manures, compost, cover crops) and regenerative practices (no-till, crop diversity, agroecology) shows they restore soil health by increasing organic matter and beneficia

• Regenerative Agriculture: Restoring Ecosystems¢ Resilience and Productivity: A Review (opens in new window)

  This study found: Regenerative agriculture builds soil health and ecosystem services through practices like no-till, cover crops, and diverse rotations. It increases soil organic matter, improves water infiltration, bo

• The invisible subsoil compaction risk under no-till farming (opens in new window)

  This study found: No-till farming risks hidden subsoil compaction from heavy machinery, impacting yields on 40% of global NT land. Solutions include respecting soil limits and using smaller/robotic vehicles.

Arid and Semi-Arid Regions

Representative Locations: Western USA, North Africa, Central Asia, Interior Australia, parts of the Sahel

Climate Context: Low annual precipitation (<40 cm or 15 inches), high temperatures, short and often unpredictable growing season. USDA Zones 7-9, Köppen BSh/BSk.

Considerations: Soil moisture is the most critical factor. Tilling when soil is too dry leads to poor fracture and recompaction. Tilling when too wet creates new compaction. Timing is crucial, often requiring a narrow window after rare rainfall events before planting cover crops. Species selection for cover crops must prioritize drought tolerance, deep-rooted varieties adapted to local conditions, and rapid establishment. Resilience of the cover crop phase is paramount; failure here means the entire intervention fails.

Mediterranean Regions

Representative Locations: California, Mediterranean basin (Spain, Italy, Greece), central Chile, southwestern Australia, Western Cape South Africa

Climate Context: Hot, dry summers and mild, wet winters. Annual precipitation 40-90 cm (15-35 inches), highly seasonal. USDA Zones 8-10, Köppen Csa/Csb.

Considerations: The distinct wet winter and dry summer seasons offer a clear target for tillage and cover cropping. Autumn tillage after summer dryness, followed by seeding cool-season cover crops on developing winter rains, is ideal. Ensure the subsoiler shanks fracture compacted soil effectively, as dry soils can "smear" rather than shatter if too hard. Deep-rooted cover crop species are vital to maintain the opened channels through the dry summer period if perennials are used, or to provide significant root biomass before seasonal termination.

Humid Temperate Regions

Representative Locations: Southeastern United States, northern Europe (UK, Germany, Poland), eastern China, Japan, New Zealand

Climate Context: Warm to hot summers and cool to cold winters with moderate to high annual precipitation (75-150 cm or 30-60 inches) distributed relatively evenly. USDA Zones 6-8, Köppen Cfb/Cfa.

Considerations: Soil moisture is generally more forgiving, but significant variations can still occur. Compaction is often linked to wet-season traffic. Tillage might be best performed in late summer or early fall when soils are drier but before significant autumn rainfall. The longer, more reliable growing season allows for a wider selection of cover crops, including deep-rooted annuals and more robust perennial mixes that can quickly re-establish soil structure. Multiple cover crop generations within a year are possible, accelerating recovery.

Cold Continental Regions

Representative Locations: Northern USA and Canada, Northern Europe, Northern Asia

Climate Context: Very short growing seasons, extreme summer heat, severe winter cold. USDA Zones 3-5, Köppen Dfa/Dfb.

Considerations: The narrow window for soil moisture manipulation and cover crop growth is the primary challenge. Tillage must be timed precisely to coincide with unfrozen, adequately moist soil, usually in late spring or early summer. Cover crop selection must focus on species that can establish quickly and provide sufficient root mass before winter dormancy or frost. Winter-hardy varieties are essential if aiming for year-round root activity. The success of the cover crop phase is highly dependent on maximizing its growth within the short season.

Subtropical Regions

Representative Locations: Southeastern USA, Southern China, Southern Brazil, Eastern Australia

Climate Context: Hot, humid summers and mild winters with generally ample rainfall. USDA Zones 9-11, Köppen Cfa/Cwa.

Considerations: High rainfall and humidity mean soil is often wet, increasing the risk of recompaction during tillage operations. Careful timing is needed to select drier periods. The long growing season supports a vast array of cover crop species, allowing for very diverse and robust mixes. These can include deep tap-rooted plants, highly productive grasses, and legumes. Extended periods of root activity before cash crop planting or between main crop cycles can accelerate structural rebuilding significantly.

Tropical Regions

Representative Locations: Central America, Southeast Asia, East Africa, Northern Australia, Northern South America

Climate Context: High temperatures year-round, with distinct wet and dry seasons or consistent high rainfall. Köppen Af/Am/Aw.

Considerations: Compaction is often exacerbated by heavy rainfall and intense farming systems. The challenge lies in managing wet soils during tillage. If dry seasons are pronounced, they provide a natural window for tillage and cover cropping with drought-tolerant species. In regions with consistent high rainfall, timing tillage for brief dry spells is critical. The long growing season allows for rapid cover crop establishment and biomass production, which are key to rebuilding structure quickly after the mechanical disturbance. Careful management is required to ensure the cover crop biomass is sufficient to protect and rebuild the soil.

Before considering one-time tillage, verify these conditions exist:

• Documented severe compaction: soil penetrometer readings >300 psi (2 MPa) at 15-30 cm (6-12 inch) depth, or water infiltration <0.5 inches/hour (<1.3 cm/hour)
• Evidence of biological remediation attempts: minimum 2 years of cover cropping, reduced livestock pressure, or other biological approaches with documented failure to improve infiltration
• Resources for immediate follow-up: cover crop seed ready, equipment for planting within 48 hours, plan for ongoing management
• Commitment documented: written statement (even if only for yourself) that this is one-time only with no future tillage

If these conditions aren't met, tillage is not appropriate. Continue with biological approaches—they will eventually work if given enough time and proper management.

Phase 1: Timing and Equipment Selection

Timing: Soil moisture is critical for success. Too wet: smearing and re-compaction as equipment creates new compaction. Too dry: shattering may not occur, or soil may fracture but not separate. Optimal moisture: field capacity (soil holds water but isn't saturated). Test by squeezing soil: should form a ball that breaks apart with light pressure.

Season: Late summer or early fall is ideal in most temperate climates. This allows immediate cover crop establishment with fall rains, giving plants 2-3 months growth before winter. Spring timing is possible but sacrifices significant growing season opportunity for cover crops. In tropical regions, late dry season or early wet season timing is critical based on local conditions.

Equipment: A subsoiler or ripper with parabolic shanks spaced 30-45 cm (12-18 inches) apart, designed to operate 30-45 cm (12-18 inch) deep. A chisel plow can be acceptable but is generally less effective than a subsoiler at fracturing deep compaction. Avoid moldboard plows or disks, as they invert/mix soil causing more biological disruption than necessary for this specific goal. The objective is to fracture the compacted layer with minimal overall surface disturbance.

Cost: $100-200/ha ($40-80/acre) USD equivalent for custom hire, or $50-100/ha ($20-40/acre) if you own the equipment and tractor. International variation in costs is substantial, driven by local equipment availability and labor rates.

Phase 2: Execution (Days 1-2)

Day 1: Operate the subsoiler across the field. On slopes, work on contour. On flat land, operate perpendicular to prevailing winds if possible to enhance fracture. The shanks should fracture the compacted layer at depth without causing excessive surface disturbance. You will feel increased resistance as shanks penetrate hardpan, followed by a breakthrough as it fractures.

Immediately after each pass (within hours): Dig an inspection hole to check fracturing effectiveness. Soil should show obvious fracture patterns extending from the shank lines. If solid blocks of compacted soil remain between shank lines, adjust shank spacing or depth or wait for better soil moisture conditions.

Day 2: Seed diverse cover crops immediately (within 48 hours maximum of tillage). Species selection is critical for success:

• Deep tap-rooted: Daikon radish, forage turnips, chicory, deep-rooted brassicas (to penetrate fractured soil and maintain channels).
• Fibrous-rooted grasses/cereals: Annual ryegrass, oats, cereal rye, triticale (to create a dense surface root mat).
• Nitrogen-fixing legumes: Hairy vetch, crimson clover, field peas, fava beans (to add fertility while building biology).
• Other beneficials: Phacelia, buckwheat, sunflowers (for beneficial insect habitat and varied root structure). Target 10-15 species minimum, ideally 20+ for maximum biological diversity and resilience. Use a high seeding rate: 1.5-2 times the normal rate to ensure robust establishment despite the disturbance. Seed using a no-till drill directly into the fractured surface, or broadcast seed followed by a light incorporation with a cultipacker or a very light harrow.

Phase 3: Cover Crop Management (Months 1-12)

Allow cover crops to establish and grow without disturbance. Avoid grazing, mowing, or additional traffic for at least the first 3-4 months. Roots need time to penetrate deeply and begin their biological work of improving soil structure.

Monitor establishment weekly during the first month. If germination is poor (<50%), identify the cause (e.g., insufficient moisture, incorrect seeding depth, seed predation by birds or rodents) and be prepared to interseed. Weak cover crop establishment is the most common cause of failure for this practice.

Observe root development by digging at the edge of the field after 2-3 months. Deep-rooted species should be penetrating 30-45 cm (12-18 inches) or more. Grass roots should form a dense mat in the top 15 cm (6 inches). Legumes should show nodulation, indicating nitrogen fixation.

Over the following months, allow cover crops to grow. In winter-killing climates, they will naturally terminate with frost. In regions with milder winters, a winter-hardy mix might persist. Do not remove the residue; allow it to decompose in place, contributing organic matter to the soil surface. If using winter-hardy species, terminate them in spring before they set seed or become overly competitive with the subsequent cash crop.

Transition Timeline & Phase-Out Strategy

This is a one-time intervention, not an ongoing practice. The goal is to restore soil function so biological processes can take over and maintain it.

• Year 0 (Tillage Year):

  • Conduct soil assessments (penetrometer, infiltration test) to document severe compaction.
  • Only till if infiltration rate is critically low (<0.5 inches/hour or <1.3 cm/hour) AND biological methods have demonstrably failed over 2+ years.
  • Immediately seed a diverse cover crop mix (10+ species).
  • Make a firm commitment that this is the final tillage event.

• Year 1-2 (Recovery Period):

  • Maintain continuous living cover on the soil surface.
  • Focus on the established cover crops, ensuring their root systems are active.
  • Monitor infiltration improvement quarterly (target: 1-2 inches/hour or 2.5-5 cm/hour by year 2).
  • Monitor earthworm populations (target: 5+ per shovelful by year 2).

• Year 3+ (Fully Regenerative):

  • Soil structure should be rebuilt through biological processes.
  • Transition to permanent no-till management for cash crops or subsequent cover crops.
  • Success indicators: Infiltration rate >2 inches/hour (5 cm/hour), earthworm populations >10 per shovelful, visible root channels and aggregate development in soil profile.

Addressing Recompaction: If compaction returns after this process, it indicates the underlying cause was not addressed. Common causes include: continued use of heavy equipment on wet soil, overly intensive livestock grazing that doesn't allow adequate pasture rest, or insufficient living root cover. Correct these management issues rather than resorting to further tillage. Success means preventing recurrence and trusting biological processes to maintain healthy soil structure.

Graduating from this practice means no longer relying on tillage as a solution, actively preventing compaction through smarter management, and trusting biological processes to keep the soil healthy and functional. The one-time tillage event becomes a historical transition step, not a recurring management strategy.

Sources behind this view

Videos & Podcasts

• Preventing bare soil and addressing compaction are critical for healthy soil biology, gas exchange, and water infiltration. Deep ripping followed by biological applications and cover crops is recommen

  How to Remove Compaction, Manage Nitrogen, and Build Soil Health Fast with Tainio and John Kempf (opens in new window) | Jump to 2:16 (opens in new window)
  

• Achieving regenerative agriculture requires addressing soil compaction, which hinders gas exchange and biology. Deep compaction needs mechanical removal, followed by cover crops and biologicals to pre

  Antimicrobial Agriculture (opens in new window)
  

• Farmers discuss no-till benefits (soil health, water retention, weed control) and challenges (labor intensity, initial cost). Strategies include tarping, mulching, cover cropping, and careful planning

  Voices from the Field: Northeast Women Leading the No-Till Revolution (opens in new window) | Jump to 24:45 (opens in new window)
  

• Implementing the six soil health principles (living root, cover crops, diversity, minimize disturbance) over 3-5 years can dramatically improve soil function, aggregation, and water cycles, reducing t

  Ep 355 – Brian Dougherty – Managing Soil Nutrients Made by Headliner (opens in new window) | Jump to 18:14 (opens in new window)
  

Community

• Advanced no-till methods for decompacting soil include subsoilers/keyline plows for deep slits, encouraging root colonization and organic matter. Integrating animals (pigs, cattle) and features like s

  Read more (opens in new window) permies.com

• Actively build soil fertility using keyline plowing for water infiltration, seeding nitrogen-fixing cover crops (clovers) and tillage radishes, occasional mowing, and rock dust application for mineral

  Read more (opens in new window) permies.com

• Strategic use of one-time tillage on dense cover crops can accelerate soil regeneration to achieve 12 inches of rich soil in two years or less, enhancing microbial activity and organic matter, and can

  Read more (opens in new window) permies.com

• Recommends a sequential, cost-effective approach to soil restoration starting with holistic grazing management, followed by biofertilizers, cover cropping, and finally Keyline plowing, emphasizing obs

  Read more (opens in new window) permies.com

Research

• Reclamation of an Ultisol Damaged by Mechanical Land Clearing (opens in new window)

  This study found: Deep tillage (chisel plow, subsoiling) effectively reclaimed compacted Amazonian soil, dramatically increasing water infiltration and crop yields for rice, soybeans, and corn compared to no-till metho

• Effects of Different Tillage Measures on Soil Physical Properties, Organic Carbon Sequestration and Crop Production in Reclaimed Farmland Filled with Foreign Soil (opens in new window)

  This study found: On reclaimed farmland, deep tillage and alternating tillage methods improved soil structure, increased soil organic carbon, and boosted winter wheat yields compared to no-till over a 7-year study.

• Altered microbial resource limitation regulates soil organic carbon sequestration based on ecoenzyme stoichiometry under long‐term tillage systems (opens in new window)

  This study found: 19-year study found no-till and subsoiling with straw retention increased soil carbon by improving microbial efficiency and nutrient availability, promoting carbon sequestration.

• Building Soil Health and Fertility through Organic Amendments and Practices: A Review (opens in new window)

  This study found: Review of organic amendments (manures, compost, cover crops) and regenerative practices (no-till, crop diversity, agroecology) shows they restore soil health by increasing organic matter and beneficia

Subsoiling is a last-resort intervention for severe soil compaction, typically adopted in degraded agricultural systems where biological methods alone struggle to initiate recovery. While valuable in specific contexts like semi-arid rangelands or heavily degraded cropland needing immediate water infiltration, its success hinges on impeccable follow-up and a commitment to regenerative principles. The true effectiveness and timeline for benefit depend critically on local soil types, climate, the severity of degradation, and the agriculturalist's strategic integration of cover cropping, controlled traffic, and permanent no-till practices afterward, rather than on the tillage event itself.

Does subsoiling offer lasting soil benefits or just temporary relief?

Temporary relief with biological follow-up

Experienced practitioners emphasize subsoiling as a critical one-time intervention to break severe compaction. This mechanical action creates openings for roots and water, enabling cover crops to establish and subsequently rebuild soil structure biologically. Without immediate, robust cover cropping and a permanent shift to no-till, its benefits are fleeting.

Sources behind this view

Sources behind this view

Videos & Podcasts

• Subsoiling should be a last resort, performed 4 inches below the compaction layer at the correct humidity, ideally after planting cover crops. Soil profiling is crucial to identify the compaction depth and avoid overuse.

  CROP Concept & Soil Compaction - Groundswell 2024 (opens in new window) | Jump to 27:38 (opens in new window)
  

• Details the development and use of a modified subsoiler ('ripper') that incrementally loosens compacted soils, combined with liquid biostimulants and tailored seed mixes, to rapidly increase rooting depth, water infiltration, and soil health, especially in clay soils.

  Episode #27: Healing Watersheds One Farm at a Time with Abe Collins (opens in new window) | Jump to 1:49 (opens in new window)
  

• Manage compaction through cover crops, living roots, and building soil aggregates, rather than tillage. Be patient, avoid working wet soils, and manage tire pressure and axle loads. Diverse root structures and biology are key.

  Managing Compaction in Regenerative Cropping Systems with Brian Dougherty (opens in new window) | Jump to 54:21 (opens in new window)
  

• Preventing bare soil and addressing compaction are critical for healthy soil biology, gas exchange, and water infiltration. Deep ripping followed by biological applications and cover crops is recommended to create disease-suppressive soils.

  How to Remove Compaction, Manage Nitrogen, and Build Soil Health Fast with Tainio and John Kempf (opens in new window) | Jump to 2:16 (opens in new window)
  

Inconsistent long-term economic benefits

Academic research indicates subsoiling benefits are often temporary, with long-term yield improvements being inconsistent or absent. Some studies show no lasting impact or even negative effects when soil properties or subsequent management do not favor sustained biological remediation.

Sources behind this view

Sources behind this view

Research

• Soil compaction problems and subsoiling effects on potato crops: A review (opens in new window)

  This study found: This review looks at the problems caused by hard-packed soil layers (subsoil compaction) in potato fields, especially from heavy farm equipment. Deep plowing (subsoiling) is often thought to help by loosening the soil, allowing potato roots to grow deeper and access more water, which is important because potatoes are sensitive to drought. However, the review found that subsoiling's benefits for potato yield and quality are usually small, don't last long, and are inconsistent. The only time it seems to help reliably is when water is the main problem. The review also discusses how soil can pack down again after subsoiling and suggests alternative methods like keeping machinery on set paths (controlled traffic) or using plants to help break up the soil (biological drilling) as promising ways to fix compaction and prevent it from coming back. These alternatives need more research to figure out the best ways to use them for potato farmers.

• Effect of subsoiling on soil physical properties and dry matter production on a Brown Soil in Southland, New Zealand (opens in new window)

  This study found: A 2.5-year study in Southland, New Zealand, investigated the impact of shallow deep tillage (subsoiling) on a specific soil type (Waikiwi silt loam). The process significantly improved soil structure by increasing large pore spaces by up to 39% and dramatically boosting water and air movement through the soil (up to 100 times faster). These benefits lasted for about two years, although some soil compaction returned in the top layer. Interestingly, while winged tines showed no negative impact on pasture (ryegrass and white clover) yield, the conventional deep tillage method actually reduced forage production by 9% in the second year of the study.

• Effect of subsoiling on soil physical properties and pasture production on a Pallic Soil in Southland, New Zealand (opens in new window)

  This study found: A three-year study in New Zealand looked at how deep tillage (subsoiling) affected soil structure and pasture growth on a specific soil type. Subsoiling significantly improved soil's ability to hold air and water, with these benefits lasting for over two years in deeper soil layers. However, for most of the study, the pasture (a mix of ryegrass and white clover) didn't grow any better. In fact, during a dry summer, pastures that were deep-tilled with winged implements actually produced 39% less forage, likely because the loosened soil dried out too quickly.

From the Web

• Offers comprehensive strategies for relieving and preventing soil compaction, including reduced tillage, cover crops, organic matter addition, improved drainage, controlled traffic, and better load distribution. Emphasizes long-term soil health and specific methods for surface and subsoil compaction.

  Source: www.sare.org (opens in new window)

Making Sense of the Differences

The core debate is whether subsoiling's immediate impact on soil structure can translate to lasting benefits or if it's merely a temporary fix. Field experience strongly suggests that its success is entirely dependent on immediate, intensive follow-up with cover cropping and a lasting commitment to biological management and no-till. Academic research highlights the variability of results and the potential for benefits to wane without sustained biological support, underscoring that subsoiling is a tool for initiating recovery, not the recovery itself.

How long does subsoiling take to pay for itself?

2-3 year break-even with optimal conditions

In favorable conditions and high-value crop systems, subsoiling costs can be recovered within 2-3 years through improved yields and water use efficiency. This requires precise soil moisture management during tillage and immediate, successful cover crop establishment.

Sources behind this view

Sources behind this view

Videos & Podcasts

• Subsoiling should be a last resort, performed 4 inches below the compaction layer at the correct humidity, ideally after planting cover crops. Soil profiling is crucial to identify the compaction depth and avoid overuse.

  CROP Concept & Soil Compaction - Groundswell 2024 (opens in new window) | Jump to 27:38 (opens in new window)
  

Research

• The Economic Feasibility of Subsoiling Solonetzic Soils in Saskatchewan (opens in new window)

  This study found: A 1995 study in Saskatchewan looked at whether deep ripping (subsoiling) was financially worthwhile for certain types of soils, called Solonetzic soils, which often have a hard layer that limits water and root penetration. The research found that deep ripping was generally a good investment, especially in irrigated areas. Even in drier areas, it paid off unless crop prices were extremely low. The costs of ripping were typically recovered through higher crop harvests within two to three years. Using higher interest rates made the returns smaller but didn't change whether it was a good idea. The study suggests that growing higher-value crops for a few years after ripping helps farmers get their investment back faster.

3-5 years practical break-even with sustained effort

Practitioners recommend planning for a 3-5 year break-even period, accounting for initial intervention costs, opportunity costs during recovery, and the sustained effort needed for biological rebuilding. Full benefit realization depends on addressing root causes of compaction.

Sources behind this view

Sources behind this view

Videos & Podcasts

• Remediate compaction by keeping soil covered with diverse living plants (fibrous and taprooted species) for 3-10+ years. Avoid tillage and freeze-thaw as primary solutions. Manage wet spots with cover crops and address ruts with shallow tillage only when dry. Cover crops are superior to deep ripping for long-term improvement.

  Managing Compaction in Regenerative Cropping Systems with Brian Dougherty (opens in new window) | Jump to 13:11 (opens in new window)
  

Research

• The invisible subsoil compaction risk under no-till farming (opens in new window)

  This study found: While no-till farming is great for soil health and reducing disturbance, a hidden problem called subsoil compaction can develop over time. This happens when heavy farm equipment repeatedly passes over the same areas, especially in fields where soil doesn't naturally recover quickly. This study found that about 40% of no-till land globally, particularly in large agricultural areas like Canada, the US, and Brazil, is at high risk of this deep soil compaction. This can lead to crops not yielding as well. To keep conservation agriculture sustainable, farmers need to be aware of this risk and consider operating within the soil's limits or using smaller, lighter, or robotic machinery.

From the Web

• Four strategies to reduce in-row subsoiling fuel costs: adopt controlled traffic, subsoil at optimum soil moisture, choose efficient shank designs, and reduce subsoiling depth to only what's necessary to break the hardpan.

  Source: www.sare.org (opens in new window)

Making Sense of the Differences

The financial recovery timeline for subsoiling varies, with optimistic academic studies suggesting 2-3 years in specific high-yield scenarios. However, field experience and a holistic view of costs, including opportunity costs and the need for sustained biological management, suggest a more realistic 3-5 year break-even period. This extended timeline acknowledges that subsoiling is just the first step in a longer regenerative transition that requires persistent effort to rebuild soil structure and function.

Note: All costs are based on recent US economic data (2024-2026) and may vary substantially by region based on local labor rates, fuel prices, material costs, and regulatory requirements.

Custom Tillage Operation

Subsoiling requires high-horsepower tractors (typically 200+ HP) and specialized heavy-duty ripping equipment. For small farms under 50 acres (20 ha), local custom operators often charge premium rates due to mobilization costs and smaller field sizes, ranging from $55 to $95 per acre ($136–$235/ha). Mid-sized operations (50–500 acres (20–202 ha)) typically benefit from better economies of scale, with custom rates falling between $40 and $70 per acre ($99–$173/ha). For large-scale operations (500+ acres), custom rates optimize toward $30 to $55 per acre ($74–$136/ha), particularly when multi-day contracts are secured. If owning equipment, capital depreciation and maintenance on a heavy-duty subsoiler over 5 years adds an implicit cost of approximately $15 to $25 per acre ($37–$62/ha) based on 500-acre (202 ha) annual usage.

Cover Crop Seed and Establishment

Following compaction remediation, aggressive cover cropping is mandatory to prevent resealing of the soil profile. For small farms, a diverse, high-performing cocktail mix typically costs $60 to $90 per acre ($148–$222/ha), including seeding labor. Mid-sized operations, when purchasing seed in bulk volumes of 5,000+ lbs, realize price reductions, leading to costs of $45 to $70 per acre ($111–$173/ha). Large-scale operations leveraging contract seeding or high-speed precision drills typically spend $35 to $60 per acre ($86–$148/ha). Costs vary based on species selection; cereal rye-based monocultures remain at the lower end of these ranges ($30–$40/acre ($74–$99/ha)), while sophisticated multi-species mixes including tillage radishes, legumes, and brassicas push costs to the upper bound ($70–$90/acre ($173–$222/ha)).

Most Spend: Most agricultural operations fall within the middle 60% of these total investment ranges:

• Small Scale: $100–$145 per acre ($247–$358/ha).
• Mid-Scale: $80–$115 per acre ($198–$284/ha).
• Large Scale: $65–$95 per acre ($161–$235/ha).

Why the Range?: The primary drivers of cost variance include equipment procurement (owning vs. custom hiring) and seed complexity. Small farms often face a "bottleneck penalty" where contractors charge by the hour rather than the acre, significantly increasing costs. Mid and large-scale operations mitigate these variable costs through bulk procurement of seed and optimized cross-farm logistics. Additionally, the intensity of soil compaction dictates the number of passes; a single-pass cross-rip vs. a single-pass straight-rip can account for a 20–30% difference in fuel and labor costs, which are the highest overhead components in this practice.

Sources behind this view

Videos & Podcasts

• Transitioning to regenerative agriculture can avoid the 'J curve' by first optimizing agrochemical use and reducing tillage intensity to generate savings. These freed-up funds are then reinvested grad

  Nicolas Verschuere, Regenerative Agriculture transition profitable from year 1 (opens in new window)
  

• Adopting soil health practices like reduced tillage and cover crops can be economically neutral or beneficial by offsetting costs of fuel, machinery, and erosion-related nutrient loss, with potential

  Winter Soil Health Virtual Series 2 (opens in new window) | Jump to 65:36 (opens in new window)
  

• Transitioning to regenerative farming costs $75k-$140k over two years but saves money compared to conventional nitrogen expenses ($195k/year). Start small (50-100 acres) with cover crops (hairy vetch,

  Farmers Going Broke Buying Fertilizer - These Farms Haven't Bought Any in Years (opens in new window) | Jump to 7:12 (opens in new window)
  

• Century is integrating soil disturbance reduction (saving £30-£100+/hectare), cover crops, and input reduction (improving nitrogen use efficiency to 92%) across its farms, utilizing grants and explori

  Regen Farming – Can We Afford Not To Do It? - Groundswell 2023 (opens in new window) | Jump to 14:23 (opens in new window)
  

Community

• Seven strategies accelerate cover crop ROI: managing weeds, grazing, addressing compaction, transitioning to no-till, improving soil moisture, managing nutrients (using legumes like Hairy Vetch/Austri

  Read more (opens in new window) sustainableagriculture.net

Research

• Economic Impacts of Cover Crops for a Missouri Wheat–Corn–Soybean Rotation (opens in new window)

  This study found: Missouri study: Cover crops in wheat-corn-soybean rotation initially reduced profits but became positive by year four. Improved soil health and carbon sequestration potential.

• Farmers employ diverse cover crop management strategies to meet soil health goals (opens in new window)

  This study found: Farmers use diverse cover crop methods, with costs around $99/ha. 'Planting green' increased. Varied practices and uncertain profitability make adoption challenging.

Economic Scenarios

The return on investment (ROI) for subsoiling is intrinsically linked to the "biological bridge" created by subsequent cover crops.

• Best-Case Scenario ($500–$900 profit per acre): In regions with adequate moisture, rapid infiltration gains allow for earlier spring planting and deeper root access during summer dry spells. Yield increases of 20–30% emerge by Year 2, with reduced input requirements for nitrogen due to improved biological cycling. The initial $80–$150/acre ($198–$371/ha) investment is typically recouped within 18–24 months.
• Typical-Case Scenario ($150–$400 profit per acre): Yields recover to baseline levels by Year 2 and move toward a 10–15% increase by Year 3. Break-even timing occurs at roughly 36 months. Costs are balanced by lower irrigation pumping energy and moderate moisture storage gains.
• Worst-Case Scenario ($450–$900 net loss per acre): If poor cover crop establishment occurs, the loosened soil "re-compacts" due to heavy rain impact, effectively wasting the $80–$150/acre ($198–$371/ha) investment. Combined with a 10–20% yield drag during the transition, the total financial impact can reach $450–$900/acre ($1,112–$2,224/ha) over a 3-year period.

Market Factors and Risk Mitigation

Profitability is sensitive to fuel indices and grain prices. High fuel costs can inflate subsoiling expenses by 15–20% in a single season. Risk is mitigated by ensuring that subsoiling is performed only when the soil profile is at the correct moisture content (the "friability window"). Working soil that is too wet leads to "smearing" at depth, which creates a deeper, harder compaction layer, potentially costing 50% more to remediate in the future. Integrating soil moisture sensors or conducting hand-shake field tests—where a soil ball should crumble upon pressure, not create a ribbon—can prevent the need for a "do-over" tillage pass.

Transition Period Risks

Subsoiling serves as a high-risk transition tool. Yield dips represent the largest hidden cost, often occurring in year one as the soil undergoes "biological shock." Establishing a cover crop immediately is a 100% vital requirement to "bridge" the soil structure. If the cover crop fails (a 20–30% probability in arid or variable climates), erosion risk increases significantly, as the loosened soil is highly susceptible to wind and water runoff. To mitigate this, landowners should budget for an additional 25% of the cover seed cost to be earmarked for potential "patch-in" seeding or specialized equipment for drill-seeding into potentially uneven, freshly ripped soil.

Sources behind this view

Videos & Podcasts

• Achieving regenerative agriculture requires addressing soil compaction, which hinders gas exchange and biology. Deep compaction needs mechanical removal, followed by cover crops and biologicals to pre

  Antimicrobial Agriculture (opens in new window)
  

• Transitioning to regenerative agriculture can avoid the 'J curve' by first optimizing agrochemical use and reducing tillage intensity to generate savings. These freed-up funds are then reinvested grad

  Nicolas Verschuere, Regenerative Agriculture transition profitable from year 1 (opens in new window)
  

• Adopting regenerative practices should start small and incrementally, focusing on soil health over short-term yields. Collaboration, strategic nutrient sourcing, and leveraging resources like Continuu

  Regenerative Ag Reality (opens in new window) | Jump to 30:37 (opens in new window)
  

Research

• Reclamation of an Ultisol Damaged by Mechanical Land Clearing (opens in new window)

  This study found: Deep tillage (chisel plow, subsoiling) effectively reclaimed compacted Amazonian soil, dramatically increasing water infiltration and crop yields for rice, soybeans, and corn compared to no-till metho

• The invisible subsoil compaction risk under no-till farming (opens in new window)

  This study found: No-till farming risks hidden subsoil compaction from heavy machinery, impacting yields on 40% of global NT land. Solutions include respecting soil limits and using smaller/robotic vehicles.

• Regenerative Agriculture: Restoring Ecosystems¢ Resilience and Productivity: A Review (opens in new window)

  This study found: Regenerative agriculture builds soil health and ecosystem services through practices like no-till, cover crops, and diverse rotations. It increases soil organic matter, improves water infiltration, bo

• Building Soil Health and Fertility through Organic Amendments and Practices: A Review (opens in new window)

  This study found: Using organic amendments (manures, composts, cover crops) and regenerative practices (no-till, crop diversity) restores soil health by increasing organic matter and beneficial microbes, leading to mor

Skill Requirements:

• Soil Science Understanding: A fundamental grasp of soil structure, compaction, soil moisture dynamics, and biological processes is crucial for timing tillage and selecting cover crops. Understanding how roots interact with soil, the role of organic matter, and the impact of anaerobic conditions is vital.
• Cover Crop Management Expertise: Knowledge of diverse cover crop species, their growth habits, nutrient needs, termination methods, and compatibility with local climate and subsequent cash crops is essential. Selecting a mix of 10+ species requires more than basic cover cropping knowledge.
• Equipment Operation: Proficiency in operating tractors and subsoilers, ensuring they are set to the correct depth and spacing, and maintaining soil moisture optimal for fracture without smearing.
• Observation Skills: Ability to meticulously observe soil conditions (moisture, structure, root development, earthworm activity) and react appropriately.

Labor Needs:

• Tillage Phase: Requires a skilled tractor operator for 1-2 days per field.
• Seeding Phase: Involves loading seed, calibrating drills, and operating seeding equipment, often completed within 1-2 days.
• Cover Crop Management: Ongoing monitoring, potential reseeding, and eventual termination require dedicated time throughout the cropping cycle. This is often the most labor-intensive phase for observation and decision-making.

Expertise and Support:

• Local Agronomists/Extension Services: Seek advice on soil testing, compaction assessment, and cover crop species recommendations tailored to your region.
• Regenerative Farming Peers: Connect with farmers who have successfully implemented this practice or similar transitions. Their practical experience is invaluable.
• Specialized Consultants: For complex situations or large-scale operations, consider consultants with expertise in soil remediation and regenerative cropping systems.
• International Context on Labor: In regions with lower labor costs, the economic equation for custom hiring versus owning equipment might shift. However, the need for skilled operators and knowledgeable managers remains globally consistent. DIY approaches might be more feasible but require more time and specific training.

Cost of Expertise: Consultation fees vary widely. A general rule of thumb is to budget $500-2,000 USD equivalent for initial consultations or detailed farm planning assistance, depending on the complexity and duration. Investment in knowledge sharing through workshops or courses is often more cost-effective.

Tillage Equipment

• Subsoiler/Deep Ripper: The primary tool. Requires a tractor with significant horsepower (typically 100-250+ hp depending on soil resistance, depth, and shank spacing) capable of pulling the implement through compacted layers. Shanks are designed to fracture soil with minimum surface disturbance.

  • Cost: Custom hire rates as noted in the 'Costs' section ($50-200/ha). Purchase price for a new 3-shank subsoiler can range from $6,000-20,000+ USD equivalent, significantly more for larger or more advanced models. Used equipment can be found at lower prices, but condition is critical.

• Chisel Plow: A less effective but sometimes more accessible option for deep loosening. It has wider shanks and disturbs more surface soil. May be used if a subsoiler is unavailable, but effectiveness on severe compaction is reduced.

  • Cost: Similar range to subsoilers, often slightly less.

• Tractor: High horsepower required. Investment is significant ($50,000 - 300,000+ USD equivalent for new, reliable models), making custom hire an attractive option, especially for farms not historically reliant on heavy tillage.

Seeding Equipment

• No-Till Drill/Planter: Ideal for seeding cover crops into disturbed soil without further tillage. Ensures good seed-to-soil contact while leaving residue intact.

  • Cost: New no-till drills can range from $40,000-100,000+ USD equivalent. Used models may be available for $15,000-50,000+. Custom rental or colocation with neighbors is an alternative.

• Broadcast Seeder & Cultipacker/Light Harrow: If a no-till drill isn't available, broadcasting seed followed by a cultipacker or a light pass with a tine harrow can suffice. This method may offer slightly poorer seed-to-soil contact but is more accessible.

  • Cost: Broadcast seeders vary from $1,000-5,000+ USD equivalent. Cultipackers/light harrows: $1,000-7,000+ USD equivalent.

Other Infrastructure Needs

• Soil Testing Equipment: Essential for monitoring progress.

  • Penetrometer: To measure soil resistance to penetration ($100-500 USD equivalent).
  • Infiltration Rings: To test water infiltration rates ($50-150 USD equivalent for basic rings).
  • Spade/Auger: For visual soil assessment.

• Record Keeping System: To track tillage dates, cover crop species, seeding rates, soil test results, and observations over time. Essential for learning and demonstrating progress. Digital farm management software or simple spreadsheets can be effective.

International Sourcing: Equipment availability and cost vary greatly by region. Many farmers in developing nations may rely on sharing equipment, custom hire services, or adapting existing tools. Focus should be on the function of the equipment (fracturing, seeding) rather than a specific model name. When considering new purchases, explore local manufacturers and reputable used equipment dealers outside of major agricultural hubs.