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Yetter Farm Equipment

What’s the Difference Between Zone Tillage and Coulter Tillage?

Ever wondered what the difference is between zone tillage and coulter tillage? If so, you've come to the right place! In this brief guide, we outline the basic principles of these two tillage methods, along with their pros and cons and fertilizer application tips.


Zone Tillage

Zone tillage is the indirect loosening of an area of soil between two coulter blades stagger mounted on either side of the planter row. The following are some key points to keep in mind when planning for a zone tillage setup.

  • Zone tillage allows for effective loosening of the soil in the seed placement area while allowing for the use of a planter-mounted residue clearing device. The residue clearing device will promote early germination due to soil warm-up without the need for tillage.
  • To effectively loosen the area of soil between the coulter blades without burying residue, it is recommended that narrow-profile coulter blades be used. The narrow profile blades will fracture and lift the soil without causing excessive tillage.
  • By using narrow-profile blades to merely fracture the soil, moisture in the seedbed will be maintained.
  • Excessive tilling and turning the soil will warm up the ground at a faster rate. However, much-needed moisture will be lost due to the soil being overly exposed to the air.
  • Excessive tillage may bring weed seed to the surface, where it can germinate and cause problems with weed control.


Illustration of zone tillage setup


Coulter Tillage

Coulter tillage is the direct loosening of soil by a coulter blade. This can be accomplished using a single coulter or the combination of several coulters. The coulters should be able to accommodate a variety of blade styles to match changing soil types and soil conditions. The following are some key points to keep in mind when planning for a coulter tillage setup:

  • Coulters operating directly in-line with the planter row unit should NEVER engage the soil at a depth below seed placement. There are several reasons for this:
    • Loosened soil below the seed can develop air pockets, which will affect seed germination due to poor seed-to-soil contact.
    • Loosened soil below the seed may settle, especially after a rain, causing the seed to drop below the desired planting depth.
    • Deeply working the soil in this area will reduce much-needed moisture.
  • Coulters operating directly in-line with the planter row should provide a wide enough area of loosened soil to allow for sufficient firming around the seed and overcome any potential compaction from the seed double disc openers.
  • Coulters mounted on the planter frame should be adjustable for variable depth settings.
  • In most installations, coulters mounted on the planter frame should be allowed to pivot. Rigid-mounted coulters can undergo an excessive amounts of stress and transfer it to the planter, especially when negotiating a turn or encountering heavy obstructions.
  • Excessive coulter tillage can bury more residue than compensated for by soil conservation regulations.
  • Coulter tillage with aggressive coulter blades can lead to soil erosion problems on contoured ground.


Fertilizer Applications in Zone Tillage and Coulter Tillage

In most cases, it is recommended that fertilizer be applied at a localized point slightly below and to the side of the seed placement area. Misplaced fertilizer could prove less effective or result in germination failure. The following are some key points to remember when applying fertilizer in zone and coulter tillage situations:

  • Fertilizer coulters should be equipped with narrow-profile blades. These blades will provide a clean, narrow slot in which fertilizer may be placed.
  • Aggressive coulter blades are not recommended for fertilizer applications for the following reasons:
    • Insufficient penetrations may result in shallow placement.
    • Thrown soil may carry fertilizer out of the intended zone.
    • Overly tilled, moist soil may build up under the seed double disc opener depth gauge wheels.
  • Knife-style applicators are generally preferred over injectors because:
    • Fertilizer knives ensure pinpoint placement.
    • Injectors apply fertilizer in a band (the lower the pump pressure, the poorer the accuracy range).
    • Injectors supplied by low-pressure pumps may dribble fertilizer on the soil surface instead of at the desired depth.


Illustration of excessive coulter tillage with maximum soil distruption


Illustration of coulter tillage setup minimizing soil disturbance


Troubleshooting Guide





Seed trench not closing

Insufficient soil loosening

Move coulters close together and ensure that in operation the planter is level

Poor seed-to-soil contact

Soil is being loosened below the seed

Move the coulters farther apart, use less aggressive blades

Excessive residue loss

Aggressive coulter blades are burying residue

Use narrow-profile coulter blades

Hairpinning of residue in the seed trench

Residue is not being cleared

Use a residue-clearing device to move residue without engaging the soil

Planter skipping, seed spacing, drive wheels lifting off the ground

Planter lacks ballast to keep coulters in the soil

Add ballast to planter




Poor seed-to-soil contact

Coulter mounted ahead of planter row unit is running too deep

Set coulter 3/8" shallower than planting depth

Uneven planting depth and seed placement

Excessive soil disturbance leaving rough, uneven path for row unit gauge wheels to follow, causing row unit bounce

Use less aggressive coulter blades or use planter- mounted row cleaners to level the soil surface

Coulter mounted ahead of row unit is running at inconsistent depths

Use a planter-mounted coulter that will maintain a consistent depth relationship to the row unit


Weeds emerging in seedbed area

Excessive tillage bringing weed seed to the surface where it can germinate

Use less aggressive coulter blades or switch to a zone till system

Poor seed germination

Seed located too close to like residue may become subject to alleopathic poisoning (ex. corn following corn)

Use a residue-clearing device which moves residue instead of incorporating it into the soil

Erratic fertilizer placement

Injectors applying fertilizer in a band or on top of the soil

Use a deep-placement coulter equipped with a knife for pinpoint fertilizer placement

Overly aggressive blades are tilling the soil instead of opening a slot for fertilizer placement

Use narrow-profile blades to open a clean narrow slot

Poor seed emergence in a dry year

Excessive tillage causing additional moisture loss in the intended seedbed

Use less aggressive coulter blades or switch to a zone till system

Planter skipping, drive wheels lifting off the ground

Planter lacks ballast to keep the coulters in the soil

Add ballast to the planter

Uneven seed spacing and depth

Excessive residue in the seed trench

Use a residue-clearing device which moves residue instead of incorporating it into the soil


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