Coulters
There are four main types of coulters: smooth, bubble, ripple, and wavy (or
fluted). The smooth coulter is used mainly ridge-till systems. Table 7 shows the
other primary coulters used in conservation tillage systems and describes general
features and conditions for use.
This 25-wave coulter leaves a finely-tilled seedbed in a narrow (7/8-inch) trench.
Operating speed and soil conditions are important considerations for all coulters.
Coulters cut through crop residue and
fracture or "fluff" the soil. This helps prevent problems associated with
"hairpinning" or pushing the residue into the soil. Producers typically mount one
coulter per planter or drill row unit. However, several popular configurations
include dual and triple coulters working a zone 4-10 inches wide (zone-till).
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The information provided in the table is intended as a guideline only. Coulter
performance is site-specific and may vary depending on soil conditions as well as
how the operator runs the equipment. The fluted-type may have the advantage for
avoiding sidewall compaction
in heavy soils. In low-moisture regions, it may be
best not to use a coulter at all. Keep planting speed at 5 mph or slower to
reduce the amount of soil that may be thrown out of the row by coulters.
Consult with knowledgeable farmers, conservation agency personnel, equipment
dealers, and others before making a purchase.
Fertilizer attachments
Many planters and drills have fertilizer attachments. Used primarily for placing
starter fertilizer for no-till and conventional row planters, the attachments are
usually in the form of knives or injectors that follow a narrow, rippled coulter. The
residue cover that remains after planting can vary, depending on the depth of
knifing and the width of the knife or coulter.
As much as 15% more residue cover can be left after planting into fragile residue
without starter fertilizer attachments. However, starter is often suggested for
cold soil conditions.
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