These coulters operate at shallow depths to avoid creating void pockets below the seed. Another variation involves making a deep vertical slit with a thin profile knife centered in the middle of an 8-inch tilled zone.

Zone tillage can be achieved by using a planter equipped with fluted coulters as well. Coulters may be operated 2 or 3 inches to 6 inches deep if the soil is dry.

Farmers in Southeastern states with particularly compacted soils have used in-row subsoiling with planter-mounted shanks in each row to create a tilled zone 12 inches deep.

Seeds are then planted in the disturbed zone directly behind the shanks.

This system is different from the two systems previously mentioned (zone tillage and strip-tillage) in that it is often used with a full width conventional-tillage system.

Effect on soil temperature

Studies have shown corn is more susceptible to delayed germination or disease in cool soil temperatures when soil is poorly drained and there is high no-till residue cover.

Other studies show that by removing residue over the row or disturbing a narrow zone (6 to 8 inches wide) the seedbed warms up more rapidly. This can help corn in the early part of the growing season; in some cases corn grain yield improved over no-till simply due to improved soil temperature.

Recently it was found that removing residue or strip-tilling to create a residue free zone improves corn germination due to increased soil temperature at the top two inches.

You can use planter attachments that move no-till residue away from the row during planting. This assists in more rapid warming of the soil and combats slow germination caused by cold and residue-covered soils.

Topography is important to consider before using strip-tillage.

In areas where the soil slope is steep or on highly erodible land (HEL), strip-tillage may not be the best choice. The disturbance of soil and removal of crop residue can create a significant water erosion problem in the row on steep slopes.

It is recommended that after soybeans, at least 70 percent residue cover should be on the surface before strip-tilling. Strip-tillage is recommended on relatively flat land with poorly drained soils, where soil temperatures tend to be cold.

(Vertical-tillage is another practice gaining in popularity. Information on vertical-tillage and additional thoughts on strip-tillage can be found by clicking hereand here).