Home > Management > Soil Management Practices > Tillage


Michelle Wander, University of Illinois at Urbana-Champaign
Joel Gruver, Western Illinois University
Last modified - September 4, 2008



Local Considerations


Real Experiences

Other Resources & Glossary



What is tillage?

Tillage is mechanical modification of soil structure. Tillage tools modify soil structure through a wide range of soil:tool interactions (e.g., cutting, milling, crushing, beating, rebound). The outcome of soil:tool interactions varies with respect to both the characteristics of the tillage operation (e.g., action, depth and width of disturbance, timing) and the characteristics of the soil that is being tilled (e.g., texture, structure, moisture, friability, plasticity).

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Why do it?

Tillage has been part of most agricultural systems throughout history because tillage can be used to achieve many agronomic objectives:

More specific tillage objectives include seed bed formation, stale seed bed formation, compaction alleviation, fracturing of soil crusts, severing/dessication of weeds, maceration of biofumigant cover crops, stimulation of soil biology, and harvesting of root crops.

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Why doesn't everybody do it?

Excessive or inappropriate tillage practices have been a major contributor to land degradation. Negative effects of tillage include:

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How is soil affected?

Tillage tools subject soil structure to mechanical stresses (e.g., compression, shear, tension). When the applied stresses exceed soil strength, soil structure fails, either by crumbling along planes of weakness (if the soil is in a friable state) or deforming if the soil is in a plastic state.

Tillage when soil is too moist (wetter than the “plastic limit”) causes smearing and creates clods that may last for the rest of the growing season. Winter freezing and thawing will generally break down clods.

Many tillage operations are designed to loosen and homogenize soil within the zone of tillage (i.e., increase macroporosity and structural uniformity), but some tillage operations are intended to shape or firm soil. Some of the effects of tillage are intentional (e.g., tillage objectives listed in "Why do it?"), while other effects are unintentional (e.g., formation of a plowpan, increased susceptibility to compaction and erosion).

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Online resources for more background information:

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How to monitor the soil


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Local considerations


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Region-specific data:


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Types of Tillage

Types of tillage



Primary tillage

Create a soil condition from which a seed beed can be prepared using secondary tillage implements. Soil disturbance is generally > 6” deep. Primary tillage is necessary when existing soil conditions prevent the effectiveness of secondary tools.

Moldboard and disk plows invert the soil in a plow layer, resulting in the  burial of most crop residues.
Aggressive tine tools such as chisel plows, rippers and subsoilers fracture soil but do not invert soil and retain more residue cover.
Aggressive rotary powered tools, such as spaders and rotary tillers, can be used for primary tillage. An acceptable seed bed can sometimes be prepared in only one pass.

Secondary tillage

Seed bed preparation – may involve pulverizing, leveling, and/or residue sizing and burial. Soil preparation is traditionally full field but can be concentrated in row zones.

 Ttillage tools used for seed bed preparation are generally referred to as “harrows”.
Most harrows are draft implements with gangs of tines, disks, rolling baskets or combinations.
Powered harrows (e.g. rotovators, rod weeder, reciprocating harrow) are also used for seed bed preparation and can accomplish more in one pass than draft tools.  


Mechanical management of weeds and residues.

Directed vs. blind cultivation equipment:
Directed (aka row crop) cultivators are used to undercut or dislodge weeds growing between crops planted on wide rows (generally > 2 feet). Shields are sometimes used to protect the crop rows.
Blind cultivation is mostly used preplant or shortly after the emergence of wide row crops but is also sometimes used in narrow row or broadcast crops.

Land shaping

Important for vegetable production systems and fields using conservation practices.

Listers/Ridge builders - come in a variety of shapes and sizes and build beds (rows or ridges) 6 to 10" high, 30 or 40" apart, separated by a furrow (interrow).
Bed shapers

Conservation tillage

Conservation practices maintain a minimum of 30% crop residue on the soil surface after planting or at least 1,000 lb/ac (1,100 kg/ha) of small grain residue on the surface during the critical soil erosion period.

No-tillage, Strip-tillage, Ridge-tillage, Mulch-tillage 


Plant the crop or cover; specialized for crops (seeds, starts) and land condition.
Some crops or covers are introduced using broadcast methods that introduce seed to the land surface.

Planters are used to plant wide rows, usually 20 to 40 inches (50 to 100 cm) – seed is singulated.

Drills are used to plant rows that are close together, usually 6 to 10 inches apart (15 to 30cm) – seed is not singulated.

Transplanters are important for vegetable production systems.

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Real experiences


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Other resources

Books and Articles

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Tillage Glossary

Bulk density – the mass of dry soil divided by the bulk volume. Bulk density is not an absolute indicator of compaction because root limiting density varies with texture. Root extension is generally limited by bulk densities > 1. 6 g/cm3 in silt loam soils. 1.6 g/cm3 is unlikely to be limiting in sandy soils and severely limiting in clayey soils.

Cultivation – shallow tillage intended to manage weeds. Can be blind (not guided by crop position) or directed (aka row crop cultivation - designed to minimize disruption of crop rows). Traditional cultivation equipment does not function well with high residues but high residues options exist. Actions include undercutting, vibration, rolling… Can be ground driven or PTO powered.

Conservation tillage – Any tillage system that maintains 30 percent or more of the soil surface covered with crop/cover crop residue, after planting.  Where soil erosion by wind is the primary concern, any system that maintains at least 1,000 pounds per acre of flat, small grain residue equivalent on the surface throughout the critical wind erosion period.

Conventional till (aka intensive tillage) - Full width tillage which disturbs all of the soil surface and is performed prior to and/or during planting. Less than 15 percent of the soil is  covered with residue after planting, or less than 500 pounds per acre of small grain residue equivalent throughout the critical wind erosion period.  Generally involves plowing or intensive (numerous) tillage trips. Weed control is accomplished with crop protection products and/or row cultivation.

Crusting – surface compaction resulting from raindrop impact, particle detachment and size sorting which leaves the finest particles concentrated at the surface. Impedes infiltration, gas exchange and seedling emergence.
Dead furrow – a narrow strip of soil (the width of a plow share) that has its plow layer excavated in the process of moldboard plowing but does not get filled in because it is on the outer edge of a field or a “land”. Secondary tillage does not completely fill in a dead furrow leaving a depression and often a zone of low fertility because of topsoil removal. Crops grow poorly in a dead furrow.

Disks – rolling circular blades that have straight or fluted edges and are intended to cut residues, pulverize soil structure and level the soil surface. Disks are normally rigged in gangs of parallel disks. The amount of soil movement caused by disks is related to the angle of the disks, the down pressure on the disks, the design of the blade (straight or fluted) and the speed at which the disks are pulled.

Draft – power required to pull a draft tillage tool such as a plow or disk.

Inversion tillage – in contrast with non-inversion tillage, inversion tillage flips over a layer (often 6 -12”) of soil burying surface residues (and associated weed seeds, spores and insect larva and eggs) in the process. The result is a surface with minimal residues that can be easily managed using traditional secondary tillage equipment but is susceptible to erosion. The moldboard plow is the standard inversion tillage implement. Disc plows also perform inversion tillage.

Lands – in the context of one way plowing, lands are rectangular sections of a larger field that are plowed one at a time. To start out, a ridge is formed in the center of a land and then plowing is down around this ridge until the land is complete. The purpose of plowing in lands is to minimize running time i.e., that is time moving between areas to be plowed.

Minimum till (aka reduced till) - tillage system that does not turn involve soil inversion and maintains a high level of surface residue.

Moldboard plow – traditional primary tillage tool consisting of the following key ground engaging parts: the plow share (which slices the soil horizontally), the moldboard (lifts and rolls soil bringing about inversion, landside (transfers the sideways thrust), coulter (slices the soil vertically). The coulter is essential if plowing sod or soil with significant residues. The moldboard plow is often the best tool for breaking sod.

Mulch till - Full-width tillage involving one or more tillage trips which disturbs all of the soil surface and is done prior to and/or during planting. Tillage tools such as chisels, field cultivators, disks, sweeps or blades are used. Weed control is accomplished with crop protection products and/or cultivation.

No till (aka zero tillage, direct drilling) - tillage system that maintains residues (even in row) and plants through these residues using specially designed equipment.

Plastic limit - The plastic limit (PL) is the soil moisture content where soil starts to exhibit plastic behavior. As a general rule, a soil is at its plastic limit when a 3mm diameter soil worm/sausage can first be formed. Soils in which the plastic limit is drier than field capacity have a narrow window of workability. Soils in which the plastic limit is wetter than field capacity have a broader window of workability and are more well suited for agriculture that involves tillage.

Plow pan – compacted layer immediately below the depth of regular tillage. Moldboard plows, disks and rotary tillers are notorious for creating plow pans.

Points – The leading edge of a stiff tine is commonly called a point. The shape of a point impacts its ability to penetrate and how much lifting and soil disturbance it causes. The front of a plow share is also called a point.

Primary tillage -  tillage used to break or fracture soil for a depth of six or more inches. Primary tillage implements vary in their ability to penetrate high strength soils and to cut through residues. Examples include  plows, heavy disks, spading machines, heavy rotary tillers, chisel plows, and subsoilers.

PTO powered tillage – in contrast with draft powered tillage implements (e.g., moldboard plow) and ground driven rotary tillage (rotary hoe), PTO powered tillage implements have greater capacity to pulverize and mix soil structure in one pass because they receive rotary power from a tractor. Rotary tillers, spading machines, rotary harrows and reciprocating harrows are examples of PTO powered tillage.

Puddling – tillage designed to disrupt aggregates and disperse clay, creating an impermeable layer that will perch water. Puddling is a tillage objective in flooded rice systems but is undesirable in other production systems.
Ridge till - Tillage system that uses cultivation to build/rebuild ridges during the early part of the growing season and then plants the next crop on ridges that have had the top sliced off during the planting process.

Rollers – rolling tools that press soil increasing its density or firmness (e.g., a cultipacker) or scarify the soil surface (e.g. Lilliston rolling baskets used for cultivation).

Secondary tillage – tillage used (generally following primary tillage) to pulverize, level and/or condition soil less than six inches deep to prepare or “fit” a seed bed.

Spading machine – a PTO powered rotary tillage tool that has large flat blades (spades) arranged in sets of 3 on a rotor. As the rotor turns, the spades plunge into the soil, lifts the dug soil and then tips to drop off the soil. The system is efficient in power use and gentle on soil structure but requires a complex and thus expensive machine. Normal operating forward speeds are slow (less than 1.5 mph). The degree of soil pulverization achieved depends on the ratio of rotor speed to forward speed, the magnitude of the speeds (rotor and forward), shape and arrangement of the shovels, the positioning of the back flap (upon which soil will rebound). Spading machines are primarily used in preparing soil for vegetable production and are most widely used and manufactured in Europe.

Strip till/Zone till – Tillage system that maintains residues between rows but relocates residues out of the planting row (up to 1/3rd of the row spacing) and may involve deep loosening in the row.

Subsoiling – tillage designed to fracture deep compacted layers, may or may not be in-row
Sweeps – wings that extend out from tines on cultivation equipment undercut weeds and lift soil causing rapid dessication.

Tilth – a holistic term referring to favorable soil physical properties for agriculture– soils with good tilth are friable, can be tilled with less draft and allow tillage objectives to be easily achieved. Similar terms include the soil is “mellow”, has good “condition” or “works like a garden”.

Tines – straight or curved, stiff or flexible, varying with respect to angle of contact, tines modify soil structure by a range of processes (e.g., cutting, lifting, vibration) that transfer draft energy to soil through a tine. Stiff tines are often referred to as shanks. Tines generally do not create significant down pressure and thus do not compact the soil below the depth of tillage. Flexible tines vibrate as they are pulled through soil and this vibration contributes to the shattering of soil structure.

Traction – resistance to wheel or track slippage, allows draft to be applied to a pulled implement.

Vertical tillage - deep tillage designed to create vertical zones (generally in row by cutting a slot, shattering, and lifting soil ) that will promote extensive rooting.

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